Optimization of Fixture Number in Large Thin-Walled Parts Assembly Based on IPSO

There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to determine the number of fixtures is ignored.In most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra waste.Therefore,this paper constructs an optimization model to minimize the number of fixtures.The constraints are set in the optimization model to ensure that the part deformation is within the surface profile tolerance.In addition,the assembly gap between two parts is also controlled.To conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia weight.In the algorithm,particles are encoded according to the fixture position.Each dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization efficiency.Finally,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality requirements.This research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

Exploring the Dual Subjectivity of Kindergarten's Self-made Play and Teaching Aids Activities from the Perspective of Children's Play Development in China

The joint development of teachers and young children is the basis for promoting the development of high-quality preschool education in the new era,and encouraging early childhood teachers to make playthings according to local conditions is both the fine tradition of China's early childhood education and the direct orientation of China's preschool education policy.Homemade play and teaching aids are some of the methods often used in kindergartens,which skillfully combine young children's daily life objects with toys and early childhood teaching,not only enriching the collective activities of young children but also cultivating children's abilities in various aspects.Kindergarten homemade"play and teaching aids"for early childhood teachers and children have their special educational significance and value,therefore,this paper is based on the children and teachers double subject basis,discussing the homemade"play and teaching aids"for children and teachers of the double subject meanings,and puts forward the realization of the This paper discusses the double-subjective meaning of homemade teaching aids for children and teachers on the basis of the double-subjective foundation of children and teachers,and puts forward specific suggestions for realizing the double-subjectivity of kindergarten homemade teaching aids to enrich the theoretical value and practical significance of homemade teaching aids,to provide theoretical references and support for the relevant staff.

Design a Special Fixture for Tractor Lever

Aiming at the problems of long time and poor machining precision in processing the tractor lever workpiece,a special fixture suitable for the tractor lever workpiece is designed by analyzing the processing technology of the lever workpiece,and the workpiece is accurately positioned and tightened under the action of the special fixture.Efficient machining of the workpiece can be achieved by using a drill template.The fixture not only has the advantages of high production efficiency,low cost and high life,but also effectively improves the processing technology of the workpiece,and has certain reference value for the subsequent fixture improvement design.

Flexible Fixture Design for the Top and End Surface Processing of NP2_NP4 Cylinder Heads

This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.

Leaky Cable Fixture Detection in Railway Tunnel Based on RW DCGAN and Compressed GS-YOLOv5

The communication system of high-speed trains in railway tunnels needs to be built with leaky cables fixed on the tunnel wall with special fixtures.To ensure safety,checking the regular leaky cable fixture is necessary to elimi-nate the potential danger.At present,the existing fixture detection algorithms are difficult to take into account detection accuracy and speed at the same time.The faulty fixture is also insufficient and difficult to obtain,seriously affecting the model detection effect.To solve these problems,an innovative detection method is proposed in this paper.Firstly,we presented the Res-Net and Wasserstein-Deep Convolution GAN(RW-DCGAN)to implement data augmentation,which can enable the faulty fixture to export more high-quality and irregular images.Secondly,we proposed the Ghost SENet-YOLOv5(GS-YOLOv5)to enhance the expression of fixture feature,and further improve the detection accuracy and speed.Finally,we adopted the model compression strategy to prune redundant channels,and visualized training details with Grad-CAM to verify the reliability of our model.Experimental results show that the algorithm model is 69.06%smaller than the original YOLOv5 model,with 70.07%fewer parameters,2.1%higher accuracy and 14.82 fps faster speed,meeting the needs of tunnel fixture detection.

Observation on Curative Effect of Self-made Wubeizi Decoction Combined with rhaFGF in Promoting Postoperative Wound Healing in Patients with Anal Fistula

[Objectives]To explore the curative effect of Self-made Wubeizi Decoction combined with recombinant human acidic fibroblast growth factor(rhaFGF)in promoting postoperative wound healing in patients with anal fistula.[Methods]A total of 82 patients with anal fistula who underwent anal fistula resection+use of setons in Luodian Hospital during January and March of 2020 were randomly divided into observation group and control group with 41 cases in each group.The control group was given rhaFGF external application regimen,and the observation group was treated with Self-made Wubeizi Decoction on the basis of the control group.After 3 weeks of treatment,the differences in curative effects of TCM syndromes were compared between the two groups.Besides,the changes in TCM symptom scores,inflammatory mediators[interleukin-12(IL-12),tumor necrosis factor-α(TNF-α),interferon-γ(IFN-γ)],anorectal functions[anal resting pressure(ARP),maximal systolic pressure(MSP)and maximum tolerated volume(MTV)of the anal canal],quality of life[GQOLI-74 scores]were compared.[Results]After 3 weeks of treatment,the total effective rate of the observation group was significantly higher than that of the control group(P<0.05);the levels of TCM symptom scores,IL-12,TNF-α,IFN-γ,ARP,MSP,and MTV in both groups were significantly lower than those before treatment,and these levels in the observation group was significantly lower than that in the control group at the same time(P<0.05).The GQOLI-74 scores of both groups were significantly higher than those before treatment,and the observation group was significantly higher than the control group(P<0.05).[Conclusions]The Self-made Wubeizi Decoction combined with rhaFGF therapy has a significant effect in promoting postoperative wound healing in patients with anal fistula.It can effectively inhibit the local inflammation of patients,facilitate the recovery of anorectal function and improve the quality of life,thus has high clinical application value.

CNC SYSTEM OF FLEXIBLE FIXTURE IN AIRCRAFT COMPONENT MANUFACTURING AND ASSEMBLY

The computer numerical control（CNC） system is suited to control varied types of flexible fixtures in aircraft component manufacturing and assembly. The mechanisms and control requirements of flexible fixtures are presented and analyzed. The hardware and software architecture and implementation of CNC system are pro- posed. The flexible fixture mechanism is described using configuration parameters. According to the parameters, the CNC system automatically generates the control feature and the human machine interface （HMI） operation function. The CNC system is implemented in a flexible fixture for skin-strlnger assembly, and results show the effectiveness of the system.

Process Analysis of Mobile Fermentation of Spent White Hypsizygus marmoreus Substrate with Self-made Mobile Fermentation Bag

The self-made mobile fermentation bag for spent white Hypsizygus marmoreus substrate was developed, and the relevant fermentation process was studied. The results showed that under the condition of single addition of Lactobacillus,nitrogen-free extract was degraded into lactic acid, leading to decreased pH value.On day 10, the fermentation effect reached the best with Lactobacillus abundance of 5.12×10~7/ml, lactic acid content of 0.48% and strong acid flavor. At this time, the fermentation material was moist without mildew and agglomeration, and was suitable for livestock and poultry. However, after 10 days, undesirable acids and mildew generated, a large amount of lactic acid bacteria died, and the fermentation material turned black and agglomerated, and became unsuitable for feeding livestock and poultry. Throughout the fermentation process, the pH value first decreased continuously until to 4.0, and then remained stable. During the fermentation of spent white H. marmoreus substrate, the nitrogen-free extract and crude fiber contents decreased, the crude protein content increased, while other indicators remained unchanged.

Modeling and Compensation Technology for the Comprehensive Errors of Fixture System

Error modelling and compensating technology is an effective method to improve the processing precision.The position and orientation deviation of workpiece is caused by the fixing and manufacturing errors of the fixture.How to reduce the position and orientation deviation of workpiece has become a technical problem of improving the processing quality of workpiece.In order to increase machining accuracy,an implementation scheme of fixture system comprehensive errors（FSCE） compensation is proposed.A FSCE parameter model is established by analyzing the influence of contact points on the position and orientation of workpiece.Meanwhile,a parameter identification method for FSCE parameter model is presented by using the 3-2-1 deterministic positioning fixture,which determines the model parameters.Moreover,a FSCE compensation model is formulated to study the compensation value of the cutting position.By using RenishawOMP60 Probe and combining vertical machining centre（SKVH850） equipment with SKY2001 Open CNC System,on-machine verification system（OMVS） is built to measure FSCE successfully.The processing error can be reduced by analyzing the cutting position of the tool with the homogeneous transformation of space coordinate system.Finally,the compensation experiment of real time errors is conducted,and the cylindricality and perpendicularity errors of hole surface are reduced by 30.77% and 28.57%,respectively.This paper provides a new way of realizing the compensation of FCSE,which can improve the machining accuracy of workpiece largely.

LOCATORS OPTIMIZATION FOR MEASURING FIXTURE DESIGN

'N-2-1' principle is widely recognized in the fixture design for deformablesheet metal workpieces, where N, the locators on primary datum, is the key to sheet metal fixturedesign. However, little research is done on how to determine the positions and the number of Nlocators. In practice, the N locators are frequently designed from experience, which is oftenunsatisfactory for achieving the precision requirement in fixture design. A new method to lay outthe N locators for measuring fixture of deformable sheet metal workpiece is presented, given thefixed number of A'. Finite-element method is used to model and analysis the deformation of differentlocator layouts. A knowledge based genetic algorithm (KBGA) is applied to identify the optimumlocator layout for measuring fixture design. An example of a door outer is used to verify theoptimization approach.

A Study on Modular Fixture Design with Intelligent Selection of Elements and Interactive Assembly

Based on the features of the design and assembly of rnodular fixtures, a new design system which combines intelligent selection of elements and interactive assembly is presented.Using the fixture design datum, the system can automatically select elements,and can interactively assemble together these elements based on AutoCAD. An example is given to illustrate it.

Numerical simulation of horizontal transversal displacement under different fixed clamping force of welding fixture for superalloy during TIG welding

A numerical model is established by Abaqus software for superalloy during tungsten inert gas （TIG） welding with welding fixture to simulate the weld temperature filed, stress and strain field, and weld plate＇s horizontal trasnsveral shift. The clamp force perpendicular to the weld plate varying with welding time was analyzed. The maximum clamp force during welding process was calculated. Under the condition of insufficient of clamping force, a half or one third of the maximum clamp force for example, the weld plate＇s horizontal transversal displacement could happen and also be computed.

Parametric Design of Modular Fixture Structure

Based on an example of its typical structure, the concept of modular fixture structure module is presented, and the structure module system of modular fixture is summarized. Then the parametric design of structure is discussed, and its advantages are also emphasized.Furthermore, some specific methods are provided, such as the selection of fixture components, the determination and input of parameters, drawing representative model,and the creation of drawing. Finally an applied example of strcture parametric design is presented.

Application and Realization of Rapid Searching Technology in the RL & SM Universal Fixture System

A searching-machining system of RL & SM (Rapid Location and State Memory) universal fixture is here introduced, and the concept of rapid searching technology and manufacturing information transformation is then described, with the appropriate control methods and key techniques for its realization being proposed and also practically realized. Theoretical analysis and experimental results show that the proposed idea and methods are feasible to serve as in the practical application of the RL & SM system.

Topological Optimization Method for Aeronautical Thin-Walled Component Fixture Locating Layout

Fixture locating layout has a direct and influential impact on aeronautical thin-walled component(ATWC)manufacturing quality.The purpose is to develop a topological optimization method for ATWC fixture locating layout to minimize the manufacturing deformation.Firstly,a topological optimization model that takes the stiffness of ATWC as the objective function and the volume of the locating structure as the constraint is established.Secondly,ATWC and the locating structure are regarded as an integrated entity,and the variable-density method based topological optimization approach is adopted for the optimization of the locating structure using ABAQUS topology optimization module(ATOM).Thirdly,through a subsequent model reconstruction referring to the obtained topological structure,the optimal fixture locating layout is achieved.Finally,a case study is conducted to verify the proposed method and the comparison results with firefly algorithm(FA)coupled with finite element analysis(FEA)indicate that the number and positions of the locators for ATWC can be optimized simultaneously and successfully by the proposed topological optimization model.

Case-based retrieval approach for machining fixture design utilizingontology

In order to develop an intelligent case-based reasoning （CBR） system to reuse fixture de- sign knowledge, ontology technology was integrated in CBR system by semantic annotation of fixture design case. Domain ontology of fixture design was constructed; concepts and relations were de- fined and represented. The 2-level similarity evaluation approach of domain ontology was presented. The concept similarity of cases was calculated as the first grade case retrieval. Numerical measure- ment was the second grade case retrieval, which adopted various methods to calculate different types of attribute values. The problem of similarity measurement of fixture design case was resolved. Pro- totype system based on the proposed method was illustrated and the retrieval approach was proved to be efficient.

A Rapid Location and State Memory Fixture System for Arbitrarily Shaped Part

A new fixture system-Rapid Location and State Memory (RL&SM) fixture system is presented.It is based on RFPE technique.In which a new method-adaptable location system is used to locating arbitrarily shapedpart.It solves the problems of part location,stock driftand accessibility of all sides of the part in machining.Any part can be machined entirely in a single setup by an appropriate machine tool.RL&SM fixture system consists of four parts:state memory,setup,data measure and information handling.The principle,components and work process of it are discussed,and some of the key techniques for industrialization are also presented.Keywords:Universal fixture,Rapid location,State memo-

Numerical simulation about the effect of fixture on the welding stress and distortion of thin aluminum plate joints

The effect of welding jig on the welding stress and buckling distortion of thin aluminum plate joints was simulated by finite element method （FEM）. The results show that the restraint distance and the heat conduction ability of the fixture do have essential effects on the residual stress and distortion. The residual compressive stress and distortion will be increasing with the increase of the restraint distance, while the residual compressive stress and distortion will be decreasing with the increase of the heat conduction ability of the fixture.

Severe skeletal bimaxillary protrusion treated with micro-implants and a self-made four-curvature torquing auxiliary: A case report

BACKGROUND Bimaxillary protrusion is a clinically common dentofacial deformity,particularly among Chinese patients.This kind of malformation can severely affect facial esthetics and,even in mild cases,is difficult to correct without surgery.Unfortunately,many patients abandon treatment because of fear of surgery.Here,we describe a case of severe skeletal bimaxillary protrusion treated with nonsurgical orthodontic treatments,highlighting an alternative treatment option.CASE SUMMARY A 31-year-old woman wished to address a severe protrusion profile(approximately 8 mm overbite)and gummy smile.Cephalometric analysis and superimposition showed a severe skeletal class II pattern with a mandibular retrusion,and proclined and protrusive mandibular incisors.Panoramic radiograph showed a missing mandibular right third molar.A diagnosis of severe bimaxillary dentoalveolar protrusion was made.Taking into account the patient’s fear of orthognathic surgery,she accepted the proposed alternative treatment using micro-implants and a self-made four-curvature torquing auxiliary.The treatment allowed for maximal en masse anterior tooth retraction,proper relocation of incisors,and alleviation of the skeletal class II pattern.Esthetically,the patient’s lip protrusion was significantly decreased as was the overjet(from 10.5 mm to 1.8 mm),and the results remained stable throughout the 2-year followup.CONCLUSION Nonsurgical treatment using micro-implants and a four-curvature torquing auxiliary may benefit severe cases of skeletal bimaxillary protrusion in adults.