To address the challenges of poor surface quality and difficult post-processing in complex internal flow channels of high strength and high conductivity (HSHC) copper alloy components fabricated by laser powder bed fusion (LPBF), this study proposed a new laser powder bed additive/subtractive manufacturing (LPB-A&SM) approach. This technique integrated in-situ femtosecond laser subtraction (FLS) to refine the contours of LPBFed specimens. A FLS effectiveness model to predict the effectiveness of the fabricating parameters was derived, and the prediction results agreed very well with the experimental results. Using HSHC copper alloy C18150, the laser ablation threshold, fabricating conditions, and side surface quality optimization were systematically investigated. The results show that effective subtraction occurs when the offset distance is less than the sum of halfwidth of the melt track and half the groove width, with the ablation area extending below the contour's lower edge. The ablation threshold was identified as 0.4 J/cm2 for C18150. A narrow femtosecond pulse width achieves deep depth and high productivity. With the optimized parameters, LPB-A&SM eliminates surface powder adhesion and reduces surface roughness by over 50 %, demonstrating strong potential for fabricating high surface quality and performance metal components with complex internal channels suited for thermal management applications.

Conventional laser-electrochemical hybrid machining is limited by inefficient laser-electrolyte energy coupling, laser defocusing, and complex tool electrodes. To address these limitations, jet-guided laser electrochemical machining (J-LECM) is proposed, in which the electrolyte jet serves simultaneously as an optical waveguide for laser transmission and as a conductive medium for localized electrochemical dissolution. The effects of peak power density (PPD) on groove geometry, surface quality, stray corrosion, jet stability, and material removal behavior of 2024 aluminum alloy were systematically investigated. Compared with the JECM baseline under the same insulating-nozzle configuration, J-LECM at a PPD of 3.40 & times; 105 W/cm2 reduced the line edge roughness by 51.8%, decreased the pitting corrosion area ratio and maximum pit size by 88.1% and 69.4%, respectively, and increased the material removal rate by 69.1%. The bottom surface roughness remained acceptable at Ra 2.50 mu m. High-speed imaging shows that laser irradiation reduces radial spreading and boundary fluctuation of the electrolyte jet. This stabilizes the contact region between the jet and workpiece and suppresses stray corrosion. Surface characterization and thermal simulation further show a staged material-removal behavior. The dominant mechanism evolves from pure electrochemical dissolution to laser-enhanced electrochemical dissolution, and finally to synergistic laser-electrochemical removal with localized thermal effects. These results clarify the coupled jet-guiding, thermal, and electrochemical mechanisms in J-LECM and demonstrate its potential for high-quality micromachining of aluminum alloy components.

The surface quality of a corrugated plate directly determines the heat transfer property of the thermal power mechanical apparatus. Traditional detection methods are impractical for real-world production, being slow and destructive. In contrast, the point laser displacement sensor, employing the optical triangle method, emerges as a promising device for assessing parts with variable curvature and highly reflective surfaces. Despite its benefits, high-density sampling by an innate frequency introduces challenges such as data redundancy and a poor signal-to-noise ratio, potentially affecting the efficiency and precision of subsequent data processing. To address these challenges, adjustable frequency data sampling has been developed for this sensor, allowing adaptive sampling for corrugated plate digitization. The process begins with surface digitization to extract discrete points, which are transformed into intersection curves using the B-spline fitting technique. Subsequently, dominant points are identified, considering multigeometric constraints for curvature and arch height. Finally, the sampling signal is adjusted based on the distribution information of dominant points. Comparative results indicate that the proposed method effectively minimizes redundant sampling without compromising the accurate capture of essential geometric features.

根据快速锻造液压机工作过程中的能量需求特性,提出了一种新型能量供给方式,即叠加供液节能技术.采用蓄能器进行中低压储能,在液压机的一个工作循环中,直接利用低压充液罐或高位油箱为快下行程充液,在变形压力较小时利用蓄能器为加压行程提供中低压成形压力,在变形压力较大时利用增压器提供高压成形压力,这 3 个过程由液压及控制系统进行平稳连贯过渡.其次,对叠加供液的相关原理进行了详述,并介绍了采用叠加供液节能技术的 35 MN快速锻造液压机液压工作原理.该技术已在实际生产中成功应用,且在不降低技术指标的前提下,装机功率低于目前标准机组的 1/3,标准机组空载损耗的电量即能满足该机组的正常运行,节能效果明显且成本低.

One effective method for fabricating liquid rocket engine thrust chambers involves using laser directed energy deposition (LDED) to produce Cu/Ni bimetals by depositing Ni-based superalloys onto a High Strength and High Conductivity (HSHC) copper alloy. However, it is difficult to fabricate strengthening layer to the surface of HSHC Cu alloy due to its extremely high thermal conductivity. This paper investigates the influence of states of the HSHC CuCuCr0.8 substrate e.g., as-built of LPBF, rolled and annealed, and direct age after LPBF at 480 degrees C for 4 h, on the formability of In718 single track by LDED. The results indicate that the thermal conductivity is significantly influenced by the state of the HSHC CuCuCr0.8 substrate. At room temperature and 300 degrees C, the order of the thermal conductivity from low to high is as-built of LPBF, rolled and annealed, and direct age after LPBF at 480 degrees C for 4 h, while at 500 degrees C, the as-built of LPBF substrate has the lowest thermal conductivity, while the rolled and annealed substrate has the largest thermal conductivity. Thermal conductivity has a significant effect on the formability of LDED. The LPBF-ed substrate has the best formability, with a minimum Ra value of 9.72 +/- 0.12 mu m, a maximum deposition depth of 193.00 +/- 4.32 mu m, and a minimum grain size of 5.2 +/- 2.6 mu m because of its smallest thermal conductivity. These findings demonstrate that using an as-built LPBF-ed substrate can improve the LDED formability of the In718 single track compared with the other two substrates. This paper presents a new approach for LDED on alloy surfaces with high thermal conductivity.

Wall thickness is an important parameter used in the characterization of the surface quality of chevron corrugated plates. However, current measurement techniques such as contact mechanical or destructive modes are timing-consuming and are limited by the complex morphology of the measured object. In this study, an optical measurement system is established for experimental evaluation of the wall thickness. Its optical design and working characteristic are described based on the triangulation principle. By performing normal vector estimation, and combining with the search results about the best possible reconstructed mesh surface, the wall thickness at each measurement point can be evaluated. A series of comparison experiments with the maximum deviation 0.043 mm show that our proposed method can provide effective and automatic technical support for dimensional detection of complex components.

本文对采用泵—蓄能器—增加器叠加供液的节能型快速锻造液压机组相关配置及成本进行研究,以实际生产过程中一火次开坯锻造成材为例,分析计算手动开坯、自动常锻锻造及自动快锻摔圆工序所需的压力油量,结合机组的实际装机情况,计算出机组所需的蓄能器、气罐、增压器的容积;分析两种类型快速锻造液压机组的液压系统主要部件的组成及差异,并进行设备成本估算.两种类型机组基本性能相近,投资成本差别在可接受范围内.节能型快速锻造液压机组具有实际及推广应用价值.

简要介绍了目前快速锻造液压机的技术现状,对其主机结构、液压传动系统、控制系统等方面的技术特点进行了分析:主机结构形式多样化,以预应力结构为主,均采用可调平面导向,立柱与横梁采用平接式或插入式结构,主缸多采用双球铰法兰连接等;液压系统传动形式模式化,形成了以高频响比例阀和伺服锻造阀组成的阀控系统,以及正弦泵组成的泵控系统3 种典型液压传动形式;控制系统标准化,均采用西门子控制器及工业以太网组成的现场网络控制系统.此外,从绿色设计、能量回收利用、预测性维护、自动锻造以及应用新技术等方面对快速锻造液压机的发展趋势进行了阐述.

Each part of a hydraulic press dissipates a large amount of energy when energy or power is transmitted. Therefore, this study proposes a 3-D vertical arrangement structure for the hydraulic press to reduce their energy dissipation. In the proposed structure, the aboveground and underground spaces are comprehensively utilized, and then the hydraulic equipment are arranged three-dimensionally and set in layers according to the functional requirements. Some equipment is connected directly to minimize the use of valves and pipelines and reduce the transmission distance of hydraulic energy between the pump station and the actuator. Furthermore, a method for scheduling the drive system in the above structure is presented to share a transmission zone with no conflict and shorten their idle time. The composition of each zone is set to match the power demand of each operation to achieve the scheduling schemes. Finally, the proposed scheme is applied to a 31.5 MN hydraulic press as a case study. Results showed that the energy efficiency increased from 43.95% to 85.03%, demonstrating excellent energy-saving potential.

The primary cause of the low energy efficiency of hydraulic presses (HPs) is the mismatch between installed power and demanded power. This study adopts the concept of a high-pressure waterjet cutting system and presents an energy-saving method to reduce the energy dissipation of HPs, where a single drive system composed of multi motor-pumps and superchargers-accumulators, is integrated into an HP and partitioned into several drive zones corresponding to load profiles. Meanwhile, a method for scheduling the above system is presented to realize an orderly energy supply with no conflict and shorten the idle time. Pump units, accumulators, and superchargers were selected according to the different load profiles to energize the actuators in various operation stages. Since the kinetic power of the hydraulic oil output from superchargers are significantly higher than those of a conventional power unit, a press with low installed power could achieve high power load operations. Finally, the proposed system was applied to a 31.5 MN forging HP as a case study. Results showed that the installed power and the energy dissipation were reduced by 56% and 52% in one working cycle, respectively. Moreover, the novel HP displayed a processing performance equivalent to that of the conventional setup.

Hydraulic presses (HPs) are often preferred in metal processing for their high load capacity. Unfortunately, they are also known for their high energy consumption and low energy efficiency. The mismatch between installed and demanded power is the primary cause of low energy efficiency among HPs. To cope with this problem, this paper proposes an energy-recovery method based on a flywheel energy storage system (FESS) to reduce the installed power and improve the energy efficiency of HPs. In the proposed method, the FESS is used to store redundant energy when the demanded power is less than the installed power. During pressing with slow falling, the stored energy is recycled in combination with an AC motor to work against the heavy load, thereby reducing the motor power burden. Furthermore, unlike traditional FESS, a variable frequency drive scheme and specific control scheme are employed to ensure the load characteristics of the motor and improve the energy storage density of the FESS. As different shapes of flywheels have different moments of inertia and energy storage efficiency, this study also examined the energy density of the FESS under different shapes and obtained the best fit shape for the hydraulic power unit. Finally, a test platform is set up to verify the effectiveness of the proposed hydraulic drive system. Results show that the installed power is reduced by approximately 41.9 % and the energy consumption is reduced by 53 %, compared to the traditional HP.

Fabricating high strength high conductivity (HSHC) Cu alloy inner parts by laser powder bed fusion (LPBF) and high-strength steel out layers on Cu alloy surfaces by laser-direct energy deposition (LDED), e.g., laser powder hybrid additive manufacturing (LPH-AM), has shown promise in the development of rocket engine thrust chambers with large thrust forces. In this study, we successfully fabricated a QCr0.8 HSHC Cu alloy/S06 stainless steel bimetal structure via In718 multi-interlayer using LPH-AM. We investigated the relative density, defects, microstructure, and interfacial characteristics of the bimetal structure in detail. The results indicate that the sample achieved up to 99.9% relative density with no naked defects and good metallurgical bonding at the QCr0.8/In718 and In718/S06 interfaces. The LPH-AM-ed QCr0.8/In718 interface exhibited a combination of columnar and equiaxed dendrites. The vertically combined sample exhibited an average ultimate tensile strength (UTS) and break elongation (EL) of 300.3 +/- 10.6 MPa and 15.0 +/- 1.4%, respectively, with fracture occurring at the QCr0.8 side. This study provides a new method for fabricating complex-shaped Cu/steel bimetal components, such as rocket engine thrust chambers. (c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Al-Zn-Mg alloy is receiving a growing number of attentions due to the strategic demand in the aerospace in-dustry. But crack is a headache problem in Al-Zn-Mg alloy fabricated by Laser Powder Bed Fusion (LPBF). This paper investigated the characteristics, formation mechanisms and process control of the cracks in LPBF fabri-cation of Al-3.6Zn-0.6Mg alloy. Cracks in LPBF fabrication of Al-3.6Zn-0.6Mg alloy were found to be solidifi-cation cracks. Solidification cracks were initiated by fracture of Mg contained liquid film. Fracture of liquid film was because the pressure drop reached the critical pressure. The pressure drop increased with the increase of scan speed and decrease of laser power. Small pressure drop is helpful to reduce crack susceptibility. Crack-free Al-3.6Zn-0.6Mg alloy were fabricated by reducing scan speed and increasing the laser power. The optimized laser power was 490 W, scan speed was 400 mm/s, scan space was 0.08 mm, laser focus shift was-3.5 mm. Crack-free Al-3.6Zn-0.6Mg alloy exhibited a tensile strength of 306.7 +/- 7.4 MPa, yield strength of 214.3 +/- 3.1 MPa and elongation of 5.5 +/- 1 %. The study gives a direction to control the solidification crack in LPBF fabrication of Al-Zn-Mg alloy.

本文针对快速锻造液压机组装机功率高、能耗大、使用成本高、影响企业经济效益的难题,研发了一种节能型快速锻造液压机组:采用蓄能器进行中低压储能,压机快下时充液罐单独充液,加压时蓄能器供压,加压过程中压力不足时增压器投入,三者在工作过程中无缝衔接;同时锻造操作机也共享蓄能器储存的能量.采用这一技术的35MN快速锻造液压机组已在生产实际中成功应用,机组的装机功率低于传统快速锻造液压机组的1/3,节能节电,使用成本低,具有较好的经济效益.

针对传统的22 MN泵控锻造液压机组控制系统复杂、 运行过程稳定性较差、 响应速度较慢等技术现状,对泵控锻造液压机组的组成结构、 传动方式及其组件的运动特性进行了研究.利用AMESim软件建立了正弦泵偏心摆变量机构模型,仿真分析了偏心摆变量机构的控制性能和动态响应特性;建立了锻造液压机液压伺服控制系统模型,仿真分析了液压机在空载、镦粗、 常锻和快锻4种不同运行工况下的动态特性.仿真结果表明:偏心摆变量机构设计合理,控制性能较高,能够满足小位移高频快速换向和较大驱动力的实际生产需求;液压机液压伺服控制系统的控制精度高、 运行平稳、 响应速度快,系统的节流损失和溢流损失小,能量利用率高.

针对锻造液压机系统中部分执行机构需要很高的工作压力,而其余大部分机构所需工作压力比较低的情况,提出了一种基于双向增压器的新型液压储能系统.泵组输出的油液经过增压系统增压后,油液压力得到显著提升,然后与传统液压动力单元一起为主工作缸供能.该系统克服了液压机加工过程中负载的时序性和周期性,因此,在液压系统设计过程中可以选择装机功率更低的电机-泵组单元,从而组成更为经济合理的液压系统.通过仿真结果可知,采用双向增压装置后系统的输出流量保持较高的稳定性与响应性,且与传统液压机相比,具有质量轻、体积小和结构紧凑的优点,应用前景十分广阔.

锻造液压机系统的组成设备数量较多,设备的排布方法一般采用地面平面布置,占地面积广,各设备之间的液压传输管路较长,管路中迂回现象普遍存在,且由于流阻的存在,必然会带来压力损失,使得系统效率降低.针对上述现象,提出一种立体式排布液压机系统,将液压机组设备进行立体式排布并按功能需求进行分层设置,使主液压传动系统的泵、控制阀组与工作缸距离最近,液体压力能在泵站与执行机构间传输距离最短,实现液压传输管路最短化,降低液体传输损失,提高液压系统传动效率和响应速度.

Copper/steel is a typical bimetal functional material, combining the excellent electrical and thermal conductivity of copper alloy and the high strength and hardness of stainless steel. There has been recent interest in manufacturing copper/steel bimetal by directed energy deposition (DED) due to its layer-by-layer method. However, cracks tend to form on the copper/steel interface because of the great difference in thermal expansion coefficient and crystal structure between copper and steel. In this work, interfacial characteristics and mechanical properties of the copper/steel bimetal were studied from one layer to multilayers. The laser power has a great influence on the Cu element distribution of the molten pool, affecting the crack formation dramatically on the solidification stage. Cracks tend to form along columnar grain boundaries because of the Cu-rich liquid films and spherical particles in the cracks. Crack-free and good metallurgical bonding copper/steel interface is formed at a scanning velocity of 800 mm/min and the laser power of 3000 W. The ultimate tensile strength (UTS) and the break elongation (EL) of the vertically combined crack-free copper/steel bimetal are 238.2 ± 4.4 MPa and 20.6 ± 0.7%, respectively. The fracture occurs on the copper side instead of the copper/steel interface, indicating that the bonding strength is higher than that of the Cu-Cr alloy. The UTS of the horizontally combined crack-free copper/steel bimetal is 746.7 ± 22.6 MPa, which is 200% higher than that of the Cu-Cr alloy substrate. The microhardness is 398.6 ± 5.4 HV at the steel side and is 235.3 ± 64.1 HV at the interface, which is 400% higher than that of the Cu-Cr alloy substrate. This paper advances the understanding of the interfacial characteristics of heterogeneous materials and provides guidance and reference for the fabrication of multi-material components by DED.

四辊卷板机现有的卷制工艺数学模型通常未考虑非对称卷圆时卷板曲率中心的偏移对下辊位置的影响.在考虑卷板机弯卷过程中板材回弹的基础上,结合数学-力学的分析,确定卷板曲率中心偏移后下辊的精确位移,建立板材弯矩和受力与侧辊和下辊位移之间的关系,提出了四辊卷板机轴辊位移的一种计算方法;通过弯矩和压力确定剩余直边与下辊位置角?b之间的几何关系,避免了剩余直边按经验取值而导致的计算误差,计算出的剩余直边符合实际生产经验.试验结果表明,通过传统理论计算得到的侧辊相对位移误差在2.2％～2.4％之间,改进后的计算方法误差为1.3％,计算出的剩余直边约为板厚的1.5倍,与传统理论中预估剩余直边为板厚的1～2倍相符,该试验结果证明了改进后计算方法的有效性.新方法表明,在弯卷过程中可以由不同的轴辊位移与下辊压力的组合得到同一成形半径.

Purpose The purpose of this study is to investigate the effect of the strut size and tilt angle on the densification behavior, surface roughness and dimensional accuracy of the selective laser melting AlSi10Mg lattice structure was investigated in this study. In this study, the characteristics such as the density, up-skin and down-skin roughness and dimensional accuracy of selective laser melting forming technology manufacturing (SLMed) AlSi10Mg cellular lattice structure were carried. This work reveals the effect of the strut size and tilt angle on the geometric characteristics of SLMed AlSi10Mg and is benefit for controlling the forming performance of the SLMed cellular lattice structure. Design/methodology/approach Based on AlSi10Mg powder, the influence of the tilt angle changed from 10° to 45° with an increment of 5° were investigated, the influence of the strut size was varied from 0.4 mm to 1.2 mm with an increment of 0.2 mm were investigated. The characteristics such as the density, up-skin and down-skin roughness, dimensional accuracy and mechanical properties of SLM-ed AlSi10Mg cellular lattice structure was carried. Findings Greater than 99% relative density can be achieved for different strut size when optimal process parameters are used. In the optimized process interval, the struts with a tilt angle of 10° can still be formed well, which is higher than the design limit of the inclined angle given in the related literature. The tilt angle has a significant effect on the surface roughness of the strut. The microhardness reached to 157 ± 3 HV, and the maximum compressive strength was 58.86 MPa, with the optimal process parameters. Originality/value In this study, the characteristics such as the density, up-skin and down-skin roughness and dimensional accuracy of SLMed AlSi10Mg cellular lattice structure were carried. With the optimal geometric parameters, the authors tested microhardness and compressive strength of the cellular lattice structure. The results of this study provide theoretical and experimental basis for the realization of high-quality manufacturing and optimization design of aluminum alloy cellular lattice structure, which will meet more diversified industrial needs.