To meet the demands for lightweight design and high-conductivity connections in new energy vehicles, the high-quality joining of dissimilar Al/Cu metals has emerged as a critical research focus. In this study, laser welding was performed on 2 mm-thick 1060 pure aluminum and T2 copper plates. The effects of laser power (3.6–4.0 kW) and welding speed (0.9–1.5 m/min) on the interfacial microstructural evolution and mechanical properties of the lap joints were systematically investigated. The results demonstrate that the macroscopic morphology of the weld is primarily governed by heat input: excessive laser power induces transverse cracking, whereas an overly low welding speed promotes porosity. Microstructural analysis revealed that intermetallic compounds (IMCs), such as Al2Cu, AlCu, and Al4Cu9, predominantly form at the interface, with their morphology and distribution varying significantly depending on the heat input. Under the optimized parameters of a 3.8 kW laser power and a 1.2 m/min welding speed, sufficient mixing of the molten Al and Cu was achieved. This promoted the formation of fine, dispersed IMCs accompanied by a continuous Al–Cu eutectic layer at the interface, yielding a maximum tensile-shear load of 1561 N. This research elucidates the intrinsic relationship between heat input and the microstructure–property correlation of Al/Cu laser-welded joints, identifying a viable process window for 2 mm-thick sheets and providing theoretical and practical guidance for joining dissimilar medium-thickness metal plates.

A 3D elastic-plastic FE model for simulating the force controlled stretch-bending process of double-cavity aluminum profile was established using hybrid explicit-implicit solvent method.Considering the computational accuracy and efficiency,the optimal choices of numerical parameters and algorithms in FE modelling were determined.The formation mechanisms of cross-section distortion and springback were revealed.The effects of pre-stretching,post-stretching,friction,and the addition of internal fillers on forming quality were investigated.The results show that the stress state of profile in stretch-bending is uniaxial with only a circumferential stress.The stress distribution along the length direction of profile is non-uniform and the maximum tensile stress is located at a certain distance away from the center of profile.As aluminum profile is gradually attached to bending die,the distribution characteristic of cross-section distortion along the length direction of profile changes from V-shape to W-shape.After unloading the forming tools,cross-section distortion decreases obviously due to the stress relaxation,with a maximum distortiondifference of 13％before and after unloading.As pre-stretching and post-stretching forces increase,cross-section distortion increases gradually,while springback first decreases and then remains unchanged.With increasing friction between bending die and profile,cross-section distortion slightly decreases,while springback increases.Cross-section distortion decreases by 83％with adding PVC fillers into the cavities of profile,while springback increases by 192.2％.

文章基于Geomagic Studio、Catia、UG软件对头盔进行逆向重建工程.一部分头盔零部件采用三维扫描仪扫描采集点云,通过Geomagic Studio进行补孔、修点、去除不必要的特征导出可用的STL格式,运用Catia软件进行部件大体特征逆向,导入进UG进行细节部分特征正向建模.另一部分零部件由于零件特征简单为简化工作量,用游标卡尺直接进行尺寸测量,用UG进行有参建模.为验证构造的模型能否进行实际生产,将部分模型导入UG进行虚拟装配,再采用3D打印设备打印零部件进行实际装配,结果表明正逆向建模相结合方法的有效性.

基于新的数据交换标准STEP-NC,分析了XML语言与EXPRESS语言的映射关系及几种类型的具体映射,提出一种XML Schema库的建立及文件之间的相互转换方法,使数控加工文件可以在网络间进行传播,实现了信息的集成与共享,提高了数控系统的开放性,为企业间的数控加工文件的流通提供了便利.通过加工零件实例测试了STEP-NC加工文件转换成XML文件、下载,然后再把XML文件转换成STEP-NC文件的过程,验证了方法的正确性和有效性.

中国特色的职业院校建设离不开"高素质""高水平"的"双师型"师资队伍,人才培养的规程与质量取决于教育教学的实施者——教师.教师的职业能力水平高低,对职业院校人才的输出质量有着直接影响.因此,如何对教师职业能力做出有效评价就至关重要,本文基于现有层次分析法和统计分析法,将理论研究与实践研究相结合,质性研究与量化研究相结合,将德尔菲法(Delphi Methods)和分层分析法(AHP)结合,提炼出完整的职业院校教师职业能力体系及权重,从而针对我国职业院校教师能力要求,构建科学的能力评价指标体系.

应用CEMA算法计算向上倾斜带式输送机的卸料轨迹时,会存在一种特殊情况,其计算出的理论卸料轨迹会与卸料滚筒发生干涉,造成计算结果与实际情况不吻合,结果偏差较大.为解决这一缺陷,基于CEMA算法对带式输送机卸料轨迹进行详细的理论分析,建立向上倾斜带式输送机理论卸料轨迹与卸料滚筒发生干涉的判定公式,推导此特殊情况下的卸料轨迹方程.应用VB.NET和AutoCAD开发卸料轨迹计算和绘图程序,并通过算法修正前后的向上倾斜带式输送机卸料轨迹的对比,验证了新的计算模型的有效性.

The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional–integral–derivative (PID) control algorithm and finite element simulations. The range of extrusion speed was determined by considering the maximum extrusion load and production efficiency. By taking the optimal solution temperature of the secondary phase as the target temperature, the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was obtained. Results show that in the traditional constant extrusion speed process, the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram displacement. As the extrusion speed increases, the temperature difference at the die exit of the profile along the extrusion direction increases. The exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9 °C. Furthermore, the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container, porthole die and external environment.

采用CHW-S3AB型焊丝匹配CHF102型烧结焊剂,在50 kJ/cm大热输入下进行埋弧自动焊焊接F460Z钢,研究F460Z钢焊接接头力学性能、金相组织和断口形貌.结果表明:当焊接电流为750 A、焊接电压为39 V、焊接速度为33.3 mm/min、预热温度为180℃时,可获得最优焊接接头,其抗拉强度为583 MPa,焊缝、熔合线和热影响区-60℃冲击吸收能量分别为55 J、62 J和71 J,焊缝组织主要由针状铁素体组成,焊接接头各项指标均满足标准要求,为大热输入埋弧焊在海洋工程领域的应用提供了理论和试验依据.

基于EXCEL、ANSYS和VB.NET开发一套钢结构参数化有限元分析系统.通过修改EXCEL数据而不需要修改代码就能快速实现产品拓扑结构的更改,从而使系统适用于各种非标准化产品的钢结构参数化有限元分析.基于该系统开发的斗轮堆取料机参数化有限元计算模板验证了其高效性和便捷性.

探索了一种用于6063铝合金/紫铜连接的异种金属新型钎焊连接方法,该方法以锌铝药芯钎焊丝为焊接材料,结合了TIG焊的特点和钎焊的特点,操作方便,效率高.通过与传统炉中钎焊进行比较,对其润湿性,接头抗剪强度和微观组织进行了分析.结果表明:采用新型钎焊方法能够有效实现对6063铝合金/紫铜接头的焊接,并且得到较高的接头抗剪强度,最高可达70.2 N/mm2.

The heat transfer between Al-Mg-Si alloy and die steel during warm or hot forming process is of great influence on the temperature and stress fields of product. The interfacial heat transfer coefficient (IHTC) is also an indispensable boundary condition in the numerical simulation of warm or hot forming process, which is affected by many factors and hard to be quantified. In this study, an inverse heat conduction algorithm and new experimental apparatus were developed to determine the transient IHTC between Al-Mg-Si alloy and die steel under low contact pressure and large surface roughness. The effectiveness and feasibility of the algorithm and apparatus were verified by comparison of the calculated and measured temperatures. The influences of initial temperature of aluminum alloy, surface roughness of die steel, interfacial contact pressure and heat flux direction on the IHTC were evaluated. The results show that the calculated temperatures are in good agreement with those obtained from different measuring locations, which indicates that the inverse heat conduction method and experimental apparatus are feasible and reliable. After the samples contact with each other, the IHTC rises sharply in a short time, then slowly increases to a peak value and finally tends to decrease slightly. With the increase of the initial temperature of aluminum sample, interfacial contact pressure and the decrease of surface roughness of die steel, the IHTC increases significantly. The IHTC for the heat flux transfer from aluminum alloy to die material is obviously larger than that from die material to aluminum alloy.

The process for manufacturing automotive aluminum profiles is a multi-stage process, which includes porthole die extrusion, aging treatment, bending, and electrophoretic painting. Prediction and reduction of springback are essential in quality control of bent profiles. However, existing researches related to springback issues were mainly focused on bending process stage. This study aimed to investigate the springback behaviors of extruded aluminum profile during the whole manufacturing process by numerical simulations with experimental validations. Formation mechanism and rule of springback for aluminum profile at different process stages were revealed. The optimum process route for manufacturing bent aluminum profiles was proposed. The research results reveal that compared with the transient bending region, the springback of aluminum profile during bending process induced by the finished bending region and two straight regions is relatively small. Springback angle increases with increasing bending angle and aging time. After bending tools unloading, the stresses of the two straight zones are almost completely relaxed. However, large residual tensile and compressive stresses exist in the material adjacent to the neutral layer of aluminum profile in transient and finished bending regions. Consequently, residual stress relaxation causes additional springback of bent profiles during subsequent heat treatment processes. The additional springback angle shows linear correlation with bending angle and parabola correlation with aging time. The total springback angle is minimum for process route 3 that extruded profile is firstly bent to required shape, then treated by artificial aging and finally treated by electrophoretic painting.

Spreading extrusion is an advanced technology to produce the solid aluminum profiles with large-size, flat-wide, and thin-walled structures. Currently, little research has been reported on the hot extrusion process through spreading pocket die for manufacturing these kinds of aluminum profiles. It is a challenging task for die engineers to control the billet through die cavity with a uniform velocity. Reasonable structure design for spreading pocket die can eliminate extrusion defects and improve the performance of extrudate. In this paper, virtual tryout of spreading extrusion process for a large-size, flat-wide, and multi-ribs aluminum profile was performed through arbitrary Lagrangian-Eulerian simulation. Firstly, spreading pocket die was designed based on the theory of metal plastic flowing. The uniformity of flow velocity distribution on the cross-section of die exit was evaluated quantitatively through standard deviation calculation. Then, a series of structure modifications for the spreading pocket die was proposed to improve material flow during die cavity based on the simulated results. Thirdly, a synthetical comparison of extrusion formability for the modified and initial spreading pocket dies was carried out, including the metal flow behavior, exit temperature, residual stress of extrudate, and peak extrusion force. Finally, the modified extrusion dies were manufactured, and corresponding extrusion experiment was performed to verify the effectiveness and reliability of numerical simulations. The key design points of spreading pocket die for large-size, flat-wide, and multi-ribs aluminum profile were concluded.

The interfacial heat transfer coefficient between hot profile surface and cooling water was determined by using inverse heat conduction model combined with end quenching experiment. Then, a Deform-3D thermo-mechanical coupling model for simulating the on-line water quenching of extruded profile with unequal and large thicknesses was developed. The temperature field, residual stress field and distortion of profile during quenching were investigated systematically. The results show that heat transfer coefficient increases as water flow rate increases. The peak heat transfer coefficient with higher water flow rates appears at lower interface temperatures. The temperature distribution across the cross-section of profile during quenching is severe nonuniform and the maximum temperature difference is 300 ℃ at quenching time of 3.49 s. The temperature difference through the thickness of different parts of profile first increases sharply to a maximum value, and then gradually decreases. The temperature gradient increases obviously with the increase of thickness of parts. After quenching, there exist large residual stresses on the inner side of joints of profile and the two ends of part with thickness of 10 mm. The profile presents a twisting-type distortion across the cross-section under non-uniform cooling and the maximum twisting angle during quenching is 2.78°.

Four different welding sequences of double-pulse MIG welding were conducted for 6061-T6 aluminum alloy automobile bumpers by using nonlinear elastoplasticity finite element method based on ABAQUS software. The post-welding residual stress and deformation were definitely different among the four welding sequences. The results showed that the highest temperature in Solution A was approximately 200 °C higher than the melting point of base metal. High residual stress was resulted from this large temperature gradient and mainly concentrated on the welding vicinity between beam and crash box. The welding deformation primarily occurred in both of the contraction of two-ends of the beam and the self-contraction of crash box. Compared with other welding sequences, the residual stress in Solution A was the smallest, whereas the welding deformation was the largest. However, the optimal sequence was Solution B because of the effective reduction of residual stress and good assembly requirements.

采用FORTRAN语言建立固体界面一维反热传导的计算程序,结合自制的热电偶测温实验装置,等效研究6061铝合金挤压型材在线弯曲过程中与H13模具钢界面的瞬态换热行为,探讨初始温度、接触载荷、表面粗糙度和热流方向对接触换热系数的影响.结果表明:瞬态换热系数在开始接触的短时间内(5 s)急剧上升,然后缓慢增大至某一稳定值.当界面平均接触温度从111.5℃增大到211.5℃时,接触换热系数迅速增加.进一步提高界面平均接触温度,接触换热系数增加速率下降;随着表面粗糙度的增大,接触换热系数逐渐减小,在1.66～2.05μm范围内影响最为显著.随着载荷的增加,接触换热系数逐渐增大,敏感性逐渐下降;热流方向从铝合金到H13钢时的接触换热系数明显要比H13钢到铝合金的接触换热系数大.

针对现有的基于全局特征的三维物体识别方法和基于局部特征的三维物体识别方法在有遮挡和混叠场景中识别效果均不理想的问题,提出了一种基于点对特征的三维点云匹配算法.利用模型上的所有点对特征来完成全局模型描述构建,并在减少的二维空间上,利用快速投票方案,在局部对模型点云和场景点云进行匹配,从而恢复模型在场景中的全局姿态.实验结果表明:该算法在有遮挡和混叠的场景中识别效果比较理想.

Aiming at the problem that the lack of supporting algorithms for shape measurement using micro-nano scale 3D scanning electron microscopy( SEM),leads to its application is severely limited. a 3D measurement method based on parallax-depth mapping is proposed. Firstly,a mapping model of parallax and sample surface depth information is established. The polar line correction algorithm is introduced to ensure the accuracy of the parallax solution. Corresponding points are matched based on optical flow estimation,to obtain a dense and accurate disparity map,which ensures the quality and precision of 3D data. Finally,in order to prove the validity of the proposed micro-nano-scale 3D surface measurement method,compare it with the super-depth 3D microscope which is more commonly used in the field of micro-nano testing. The two methods are used to measure and characterize the sample in 3D. The results show that the proposed method is effective and reliable.

The entrance shape of spread die plays a crucial role in the quality control of large-scale aluminum panel production. The conventional design of spread die is generally based on the experience and expertise of the die designers or costly plant trials. Thus, it is difficult to guarantee the material flow through subsequent feeder die with the same velocity and ensure the die strength. In this work, the extrusion processes of three spread dies with different entrance shapes used generally in the real extrusion production for large-scale aluminum panel were investigated by FE simulations. Firstly, 3D-FE models for simulating the extrusion processes of the three spread dies were established by using HyperXtrude software based on ALE algorithm. Then, the effects of different die designs on the material flow behavior, extrusion load, temperature, residual stress distribution, and die deflection were synthetically studied by analyzing and comparing the simulated results. Finally, the optimal die was manufactured and corresponding extrusion experiment was carried out on a 2600-t extrusion press. The simulation and experimental results show that the die 2 with fan-shaped entrance was the optimum one among the three spread dies, where the minimum required extrusion load, uniform flow velocity at the die exit, minimum residual stress in extruded profile, and minimum die deflection were obtained. This study could provide effective guidance on the entrance shape design of spread extrusion die for the large-scale aluminum panel.

6061 aluminum alloy T-joints were welded by double-pulsed MIG welding process. Then, the post-weld heat treatment was performed on the welded T-joints. The weld microstructure under different aging temperature and time was investigated by transmission electron microscopy and scanning electron microscopy. The mechanical properties were examined by hardness test and tensile test. The results showed that the micro-hardness was sensitive to heat treatment temperature and time. Increasing temperature was beneficial to the shortening of peak aging time. There were a large number of dislocations and few precipitates in the welded joints. With the increase of post-weld heat treatment temperature and time, the density of dislocation decreased. Meanwhile, the strengthening phase precipitated and grew up gradually. When the post-weld heat treatment temperature increased up to 200 °C, large Q' phases were observed. And they were responsible for the peak value of the micro-hardness in the welded joints.