螺旋槽管材滚压成型过程的数值模拟及试验研究

利用ANSYS有限元分析软件,对螺旋槽管材滚压成型过程进行了数值模拟。根据有限元计算结果分析了螺旋槽管的主要结构参数对滚压力的影响规律。通过试验验证了用有限元法进行螺旋槽管材滚压成型过程模拟的可靠性,并得到了滚压力与槽深之间的对应关系,为螺旋槽管的二次加工提供了必要的实际指导依据。     

管材电磁成型机理与实验研究

对管材电磁成型机理进行了分析，推导出的脉冲磁场压力函数式，能准确反映管材电磁成型过程中磁场压力随时间的变化，在管材成型实验研究中，探索出管材的变形规律及各工艺参数的成型质量的影响规律，为该项技术应用提供了理论依据，有效地指导了实际生产。     

管材滚压剪切过程的数值模拟及实验研究

在ANSYS基础上开发了可以模拟管材滚压剪切过程的应用软件，利用单元死活技术对管材的切断问题进行了模拟。根据有限元计算结果分析了各种因素对切口金属流动的响影规律，通过实验验证了用有限元法进行管材滚压剪切过程模拟的可靠性和有效性，为确定合理的刀具和工艺参数提供了理论依据。     

内螺旋槽双层卷焊管的研究

介绍了内螺旋槽双层卷焊管的制造方法及这种管材的特点。分析了螺旋沟槽的各参数对管材换热效果的影响。指出确定带钢宽度、定径辊轧型尺寸、芯棒直径及定径力等参数时应充分考虑辊轧螺旋槽的影响。     

内螺纹铜管成型的工艺设计

内螺纹铜管成型的工艺比较复杂,共涉及到17个主要的工艺参数。文章介绍了内螺纹成型工艺的设计方法,利用该方法,使复杂的工艺设计变得简单直观,对关键参数的优化使工艺更合理。     

影响大螺旋角内螺纹管成型的因素分析

旋压成型是目前内螺纹铜管加工的一种主要方法,通过对无缝内螺纹铜管加工过程中的受力分析,借鉴金龙集团在实际生产中的经验,同时参考理论公式,总结出部分影响大螺旋角内螺纹铜管的成型因素,供设计内螺纹成型工艺时参考。     

内螺纹铜管成形工艺开发及换热性能研究

随着我国碳达峰碳中和战略的推进,行业标准对空调产品能效的准入门槛越来越高。增大内螺纹铜管的螺旋角可以有效提高空调换热器的能效,但增大螺旋角则会大幅增加内螺纹铜管生产制造的难度。为研发内螺纹铜管成形工艺,提升换热性能,通过逆推法设计了Φ7mm（外径）×0.23 mm（壁厚）×0.14 mm（齿高）、齿顶角15°、螺旋角35°、58齿数的内螺纹铜管（XD7）的两种旋压成形模具参数。以旋模比、拉拔速度、退火温度和保温时间作为变量,通过显微观察和力学性能测试,确定了XD7的旋压成形工艺和退火工艺。同时对比研究了XD7与同外径的普通内螺纹铜管D7（7 mm×0.24 mm×0.15 mm）的换热性能。结果表明：小的钢球半径更有利于XD7的成形,旋模比和拉拔速度分别为460和40 m/min时, XD7的成形效果最好。XD7的最佳退火工艺为在460 ℃下保温30 min。与D7相比, XD7的冷凝换热系数和蒸发换热系数分别提高了7%和8%,内螺纹铜管单管换热能效明显提升。     

内螺纹铜管成形工艺研究

阐述了内螺纹铜管成形的两种生产工艺：拉拔旋压成形法和铜带滚压成形焊接法。对两种工艺的优劣进行了研究分析，并指出了应用前景。     

高速大口径铜管内螺纹成型技术探讨

内螺纹铜管的广泛应用对内螺纹铜管成型设备提出了更高要求,本文介绍了一种高速大口径多规格的内螺纹成型设备,并对该成型工艺进行了探讨。     

采用无缝法或缝焊法生产内螺纹紫铜管之比较

空调器的小型化、轻型化以及对制冷性能更高的要求,促使其对内螺纹铜管的需求量越来越大,同时则要求内螺纹管的管径趋于小径化且壁厚更薄。内螺纹铜管的齿形有多种,如人字齿、高低齿、交叉齿、X、V、W、VVV齿等等,就内螺纹铜管的成型方法而言,目前还主要是无缝法和缝焊法两种。国内用无缝法生产内螺纹铜管的厂家有十余家,用缝焊法生产内螺纹铜管只有几家。1铜盘管的生产1.1无缝法国内铜盘管的生产始于20世纪80年代中期,当时有沈铜、广东黄浦、北京京圣、桂林有色金属加工厂等厂家。进入90年代,国内又相继投产了一批现代化的铜盘管生产线,…     

热轧带肋钢筋负公差控制与成品孔槽设计的关系

利用3D软件,对热轧带肋钢筋底圆、横肋、纵肋进行了重量计算,各部分对负公差的影响大小依次为内径—横肋—纵肋,内径尺寸的设计是控制负公差的重点,对孔型设计、加工提出了原则性建议：设计较小的内径,适当加深横肋,减小螺旋角。     

带肋钢筋尺寸超差原因及其消除

分析带肋钢筋肋间距超偏差、内径尺寸超负偏差、横肋高度尺寸超负偏差、横肋高度尺寸超正偏差、无纵肋、纵肋尺寸超正偏差、单线轧制时纵肋局部超正偏差、切分轧制时中两条纵肋大小不均、飞边等尺寸超差的原因,总结消除办法,提出持续改进措施。     

Integration of the colicin A pore-forming domain into the cytoplasmic membrane of Escherichia coli

The pore-forming domain of colicin A (pfColA) fused to a prokaryotic signal peptide (sp-pfColA) inserted into the inner membrane of Escherichia coli and apparently formed a functional channel, when generated in vivo. We investigated pfColA functional activity in vivo by the PhoA gene fusion approach, combined with cell fractionation and protease susceptibility experiments. Alkaline phosphatase was fused to the carboxy-terminal end of each of the ten alpha-helices of sp-pfColA to form a series of differently sized fusion proteins. We suggest that the alpha-helices anchoring pfColA in the membrane are first translocated into the periplasm. We identify two domains that anchor pfColA to the membrane in vivo: domain 1, extending from helix 1 to helix 8, which contains the voltage-responsive segment and domain 2 consisting of the hydrophobic helices 8 and 9. These two domains function independently. Fusion proteins with a mutation inactivating the voltage-responsive segment or with a domain 1 lacking helix 8 were peripherally associated with the outside of the inner membrane, and were therefore digested by proteases added to spheroplasts. In contrast, fusion proteins with a functional domain 1 were protected from proteases, suggesting as expected that most of domain 1 is inserted into the membrane or is indeed translocated to the cytoplasm during pfColA channel opening.     

Model structure of decorin and implications for collagen fibrillogenesis

The three-dimensional structure of human decorin, a secreted proteoglycan involved in the regulation of collagen fibrillogenesis and cellular growth, has been modeled based on the crystal structure of the porcine ribonuclease inhibitor. Both proteins contain leucine-rich repeats and share 18% identical residues. This model structure of decorin has an arch shape with the single glycosaminoglycan chain and the three N-linked oligosaccharides located on the same side of the molecule. Decorin was modeled as binding to a polar sequence of collagen type I found in the d band. The inner concave surface is the appropriate size and shape to accommodate only one collagen triple helix of approximately 3 nm in length. The binding of one collagen triple helix to decorin is proposed to play a major role in the formation of the staggered arrangement of collagen molecules within the microfibrils by preventing lateral fusion of collagen molecules.     

Numerical Predictions of Turbulent Flow over a Surface-Mounted Rib

This study accurately predicts cases of turbulent flow around a surface-mounted two-dimensional rib of varying length. The numerical method employs a finite-difference scheme for integrating the elliptic Reynolds-averaged Navier-Stokes equations and the continuity equation. The two-equation k ? ε turbulence model is employed to simulate the turbulent transport quantities and solve the problem. The near-wall regions of the separated sides of the rib are resolved by a near-wall model in a two-layer approach instead of the wall-function approximation. Computations for flow over a surface-mounted rectangular rib are conducted for varying rib lengths. Results indicate that upstream of the obstacle the length of the recirculating region remains unchanged with varying rib length, while the downstream length of the recirculating region is a strong function of rib length and changes nearly linearly as B∕H varies from 0.1 to 4.0. Reattachment on top of the rib, owing to its increasing length, affects the downstream boundary layer development.     

热轧带肋钢筋负偏差孔型设计优化

设计中通过缩小钢筋的基圆尺寸和横肋宽度、横肋高度和纵肋宽度,在保证钢筋力学性能和尺寸符合标准要求的前提下,力争获得最大的负偏差率。     

Analysis of roll-stamping process for rib grooves of ultra-high-strength beam parts

Roll-stamping technology,a new process with both roll-forming and stamping characteristics,is suitable for manufacturing ultra-high-strength beam parts,especially variable cross-section beam parts.The rib groove is a local shape often used in automotive parts for positioning,avoidance,and stiffness strengthening on longitudinal and stiffening beams.In this study,two typical rib grooves,the flat-and round-bottom rib grooves,were selected to investigate the characteristics of the roll-stamping process of rib grooves.Using the ABAQUS software platform,a simulation analysis model of rib-groove roll stamping was established and different size rib grooves produced by the roll-stamping process were compared and analyzed.The results show that when the fillet radius of the rib groove increases,the maximum Mises stress,the maximum strain,and the maximum thinning rate decrease.For roll stamping,the minimum safe fillet radii of the two types of rib grooves are 8 and 4 mm,respectively.     

Measurement of Truck Axle Weights by Instrumenting Longitudinal Ribs of Orthotropic Bridge

The longitudinal ribs of an orthotropic box-girder bridge were instrumented to measure axle weights of trucks. The bending stress in the longitudinal rib is composed of a girder component, i.e., the flexural stress due to the rib’s function as part of the box-girder’s upper flange in carrying vehicles, and a rib component, i.e., the part of stress produced in the rib when it is viewed as a continuous beam supporting wheel loads. The instrumentation locations were set close to the middle support of the two-span continuous bridge to reduce girder component and impact effect. All possible wheel-supporting ribs inside the box girder were instrumented to cover most transverse locations of truck wheels. Deviating passes as well as central passes were carried out for each traffic lane in calibration tests to catch maximum stress response. The results of the calibration tests were used to solve the influence lines of the girder component and rib component at each strain gauge. With these influence lines, the rib component was separated from girder one in the stress waves of the 3-day live traffic measurements, and axle weights of the truck traffic were subsequently calculated.     

Video-assisted thoracoscopic surgery (VATS). Endoscopic thoracoplasty technique

STUDY DESIGN: The study of two patients whose rib deformity was treated using a new endoscopic thoracoplasty technique is reported. OBJECTIVES: To report a new endoscopic thoracoplasty technique for the treatment of rib deformities associated with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Thoracoplasty has traditionally been performed as an open procedure, often necessitating additional incisions and/or tissue dissection. METHODS: Two children with significant rib humps associated with idiopathic scoliosis were treated with a new endoscopic thoracoplasty technique. RESULTS: Both children showed dramatic cosmetic improvement of their rib deformity. CONCLUSIONS: The indications for the use of video-assisted thoracoscopic surgery in the treatment of pediatric spinal deformity are expanding. We have extended our video-assisted thoracoscopic surgery repertoire to include endoscopic thoracoplasty for treatment of rib deformities associated with idiopathic scoliosis. The technique for endoscopic thoracoplasty is discussed, and illustrative cases are presented.