Search Results (13)

Electrolytic copper foil is one of the core materials in the fields of electronics, communications, and power. The cathode roller is the key component of the complete set of electrolytic copper foil equipment, and the quality of the titanium cylinder of the cathode roller directly determines the quality of the electrolytic copper foil. There typically exists a longitudinal weld on the surface of the cathode roller’s titanium cylinder sleeve manufactured by the welding method, which leads to the degradation of the quality of the electrolytic copper foil. Refining the grains in the weld zone and the heat-affected zone to close to those of the base material is a key solution for the manufacturing of welded cathode rollers. In order to effectively modify the microstructure and obtain an optimal refining effect in the weld zone of a TA1 cathode roller, a novel composite technology consisting of low-energy and fewer-pass welding combined with multi-pass rolling deformation and vacuum annealing treatment was primarily explored for high-purity TA1 titanium plates in this study. The microstructure of each area of the weld was observed using the DMI-3000M optical microscope, and the hardness was measured using the HVS-30 Vickers hardness tester. The research results show that the microstructure of each area of the weld can be effectively refined by using the novel composite technology of low-energy and fewer-pass welding, multi-pass rolling deformation, and vacuum annealing treatment. Among the explored experimental conditions, the optimal grain refinement effect is obtained with a V-shaped welding groove and four passes of welding with a welding current of 90 A and a voltage of 8–9 V, followed by 11 passes of rolling deformation with a total deformation rate of 45% and, finally, vacuum annealing at 650 °C for 1 h. The grain size grades in the weld zone and the heat-affected zone are close to those of the base material, namely grade 7.5~10, grade 7.5~10, and grade 7.5~10 for the weld zone, heat-affected zone, and base material, respectively. Meanwhile, this technology can also refine the grains of the base material, which is conducive to improving the overall mechanical properties of the titanium plate. Full article

Background: Pancreatoduodenectomy with venous resection (PDVR) may be performed to achieve tumour clearance in patients with a pancreatic ductal adenocarcinoma (PDAC) with venous involvement. This study aimed to evaluate the impact of PDVR on PDAC outcomes. Methods: In total, 435 PDAC patients with either R0 status (n = 322) or R1 status within the superior mesenteric vein groove (n = 113) were extracted from the Recurrence After Whipple’s (RAW) study dataset. PDVR patients were matched in a 1:2 ratio with standard PD patients. Comparisons were then made between the two groups (surgical radicality and survival). Results: A total of 81 PDVRs were matched with 162 PDs. Neoadjuvant chemotherapy (5.7% vs. 13.6%, p = 0.032) and R1 resection rates (17.9% vs. 42%, p < 0.001) were higher in the PDVR group. Risk factors for R1 resection included venous resection (p < 0.001 for sleeve and p = 0.034 for segmental resection), pT3 (p = 0.007), and pN1 stage (p = 0.045). PDVR patients had lower median overall survival (OS, 21 vs. 30 months (m), p = 0.023) and disease-free survival (DFS, 17 m vs. 24 m, p = 0.043). Among PDVR patients, R status did not impact on OS (R0: 23 m, R1: 21 m, p = 0.928) or DFS (R0: 18 m, R1: 17 m, p = 0.558). Irrespective of R status, systemic recurrence was higher in the PDVR group (p = 0.034). Conclusions: Independent of R status, the PDVR group had lower overall survival and higher systemic recurrence rates. Full article

In this paper, a novel precast concrete composite wall connected by tooth groove and grouted sleeve was introduced, which is produced in factories by means of structure-insulation integrated prefabrication, and the prefabrication and assembly process were presented minutely. To verify the feasibility and reliability of this novel tooth groove and grouted sleeve connection method and explore the joint connection performance and the seismic performance of the precast concrete composite wall connected by tooth groove and grouted sleeve, low-cyclic reversed loading tests with an axial compressive ratio of 0.1 were performed on two full-scale precast concrete composite walls. Moreover, the failure mode, hysteretic curve, skeleton curve, stiffness degradation, displacement ductility, energy dissipation capacity, and reinforcement strain were comprehensively discussed. The research results showed that under the vertical axial load and low-cyclic reversed load, the distributed reinforcements in the wall panel only played a structural role, while the connecting reinforcements at horizontal joints can always effectively transfer stress without bond failure, and the tooth groove and grouted sleeve connection performance was reliable. In addition, the hysteretic curves of the precast concrete composite wall connected by tooth groove and grouted sleeve were full, showing good ductile deformation capacity and energy dissipation capacity. In general, the precast concrete composite wall connected by tooth groove and grouted sleeve not only possessed favorable seismic performance but also showed obvious advantages such as green energy saving, high assembly rate, and less on-site wet operation, which can be applied to practical engineering under reasonable design. Full article

With the increasing utilization of bolted ball joint steel mesh structures in offshore floating platforms and deep-sea fish cages, the issue of seawater infiltrating the joints and members through the installation gaps of the bolted ball joint, leading to subsequent corrosion, has become increasingly prominent. This article presents an innovative method to improve the sealing performance of bolted ball joints. The approach involves creating sealed surfaces within the contact gaps between the sleeve and connecting components by adding circular grooves and sealing washers to both ends of the sleeve. Subsequently, a two-dimensional finite element analysis model of the bolted ball joint with the sealing structure was created using SOLIDWORKS 2021 and ANSYS Workbench 2022 R1. The study analyzes the sealing gasket’s contact pressure at various compression levels and evaluates its performance with bubble tests for air tightness. Research results show a linear relationship between the contact pressure and compression rate, achieving sealing pressures of 2.91 MPa, 4.22 MPa, and 5.95 MPa at compression levels of 8%, 11%, and 14%, respectively. Experimental testing demonstrates that the improved bolted ball joint exhibits excellent sealing performance. Full article

As one of the important factors affecting the stability of slide valves, the analysis and research of flow force are of great significance. In recent years, more and more experts and scholars have conducted research in this field, attempting to find methods to reduce or utilize the flow force of hydraulic spool valves. Flow force includes steady-state flow force and transient flow force, with steady-state flow force having the most significant impact on spool valves. The influencing factors of flow force are complex and diverse, including the cavitation phenomenon, shape of the throttling groove, and jet angle. At present, the main ways to reduce flow force are to design the structure of the spool valve, the structure of the valve sleeve, and the flow channel of the valve body. This article mainly reviews the definition, calculation methods, influencing factors, and methods for reducing the flow force of slide valves. This provides a new approach to reducing the flow force in hydraulic spool valves. Full article

CFRP has the potential to replace steel cables in large-span cable-stayed bridges due to its high strength and lightweight material properties. However, the weak lateral force performance of CFRP material creates the challenge of anchoring. This study introduces a new inner cone + arc + straight cylinder bond-type anchorage system to optimize CFRP tendons’ force state. Experimental and finite element analyses verified the new anchoring system’s performance. In static load tensile tests, six groups of seven CFRP tendon anchorage systems with different sleeve grooves were used to study the failure mode and load–strain variation law. The difference in mechanical properties between the new and traditional anchorage is evaluated in the finite element analysis. The results indicate that the new anchorage system can lower the stress concentration in the anchorage zone and enhance anchorage performance. The groove design of the sleeve can effectively increase the anchoring efficiency, where the groove depth is proportional to the anchoring efficiency and the groove spacing is inversely proportional to the anchoring efficiency. The magnitude of the stress inhomogeneity in the multi-tendon anchoring system during tensioning is proportional to the beginning conditions and the load size. When the inner wall of the sleeve becomes more abrasive, the force heterogeneity of the anchorage system reduces. The tests and finite element analysis show that the new anchoring may improve stress distribution and anchorage efficiency. In engineering practice, it can be utilized as a dependable anchorage system. Full article

Ti6Al4V titanium alloy (Ti-alloy) sleeved ceramic heads have become widely used in revision surgery when the hip stem is left in situ. This solution guarantees a new junction between the bore of the ceramic head and the Ti-alloy sleeve, regardless of any possible, slight surface damage to the Ti-alloy taper of the stem. However, this solution introduces an additional Ti-alloy/Ti-alloy interface pairing, which is potentially susceptible to mechanically assisted crevice corrosion. This study evaluated both qualitatively and quantitatively the damage that occurred in vivo on Ti-alloy micro-grooved 12/14 tapers of (i) primary implants with non-sleeved ceramic heads (Group 1), (ii) secondary implants with non-sleeved ceramic heads (Group 2), and (iii) secondary implants with sleeved ceramic heads (Group 3). A total of 45 explants—15 for each group, including short-, medium- and long-neck heads—underwent optical evaluation for surface damage (Goldberg scoring), surface roughness analysis, and SEM/EDX analysis. The Goldberg scores did not reveal different patterns in the tapers’ surface damage; surface damage was classified as absent or mild (surface damage score ≤2) in 94%, another 94%, and 92% of the analysed regions for Group 1, Group 2, and Group 3, respectively. Small but significant differences in morphological changes occurred in the tapers of the three groups: reductions no greater than a few percentage points in median values of roughness parameters were found in Group 1 and Group 2, while negligible changes were found in Group 3. SEM/EDX analysis revealed little (i.e., a slight increase in the oxygen content) to undetectable changes in the chemical composition on the Ti-alloy surface independently of the group. These results suggest that the Ti-alloy/Ti-alloy sleeve/taper junction is only mildly susceptible to mechanically assisted crevice corrosion. Assembling a sleeved ceramic head, with variable neck lengths up to a “long-neck”, to a Ti-alloy micro-grooved 12/14 taper of a stem left in situ does not seem to increase the risk of revision due to trunnionosis, as long as junction stability (i.e., the proper seating of the sleeved ceramic head on the 12/14 taper) is achieved intraoperatively. Full article

The existing process for the preparation of cladded rebars is too complicated for large-scale industrial production. Therefore, this paper proposes a 55#/316L rebar preparation method based on vacuum hot rolling. The microstructure and mechanical properties of the composite interface of the rebar, along with the connecting technique, were studied using transmission electron microscopy, X-ray diffraction, and Vickers hardness testing. The obtained results showed that the minimum thickness of the 55#/316L rebar cladding was 0.25 mm, which was twice that of the M 329M/M 329-11 design standard used in the United States of America. Due to the diffusion of carbon, large numbers of second-phase particles were precipitated on the stainless-steel side, which resulted in intergranular chromium depletion. After multi-pass hot rolling, the minimum bonding strength of the composite interface reached 316.58 MPa, which was considerably higher than the specified value of 210 MPa. In addition, we designed three different types of rebar connection joints: sleeve, groove-welded, and bar-welded. According to the tensile test, the bar-welded joint had higher yield strength (385 MPa) and tensile strength (665 MPa) than the base rebar (376.6 MPa and 655 MPa), as well as a very high corrosion resistance. Full article

The joint is a key component of the aviation piping system, with severe performance requirements and better requirements for connection technology. With a focus on the manufacturing demand of AA6061 aerospace pipe joints, as well as the characteristics of EMP forming technology, this paper investigates the deformation behavior of the EMP forming on AA6061 aerospace pipe joints, the influence of process parameters on the deformation behavior, and the deformation mechanism of the tube wall. The results show that under the conditions of this paper, with an increase in the initial tube-sleeve gap and discharge voltage, the degree of local deformation of the AA6061 tube wall and the trench embedding rate increase. Keeping the width and depth of the grooves as 1.14 mm and 0.23 mm, the embedding rate of the grooves is less than 85% under the clearance conditions of 0.11 mm and 0.5 mm, while the lowest voltage for the embedding rate of the grooves to reach more than 85% under the clearance conditions of 1 mm, 1.5 mm and 2 mm is 7 kV, 6 kV, and 5 kV, respectively. The metallographic organization of the deformation area shows that the tube is deformed by the intense shear at the edge of the groove of the tube sleeve, thereby showing streamlined organization characteristics and deformation characteristics. The electromagnetic pulse forming process of the AA6061 tube is mainly divided into two stages: free bulging and local deformation; the inertia of high-rate deformation causes the groove filling to exhibit volume deformation characteristics in the local deformation stage. Full article

Non-keyhole friction stir welding (N-KFSW) is a technique that can fabricate a welding joint without a keyhole through a one-time welding process. The Al–Mg–Si alloy was chosen as a research object, and the N-KFSW technique was investigated by numerical and experimental methods. Firstly, the sleeve bottoms of the N-KFSW welding tool system were innovatively optimized in this study. The optimal sleeve bottom with an 80° angle between the spiral groove and the sleeve inner side wall allowed avoiding the incomplete root penetration defect at the bottom of the stir zone (SZ), which was verified by numerical results and the C-shaped line height. Then, using a 3 mm-thick aluminum alloy as the experimental material, the material flow and joint formation characteristics and mechanical properties at 110, 150 and 190 mm/min welding speeds were studied and compared. The results showed that the SZ presented a drum shape due to the action of the clamping ring and the threads on the side wall of the sleeve. The SZ width decreased from 7.17 to 6.91 mm due to the decreased heat input. From 70 to 210 mm/min welding speed, the maximum tensile strength of the joint was 250 MPa at 190 mm/min, and the joint with relatively higher strength fractured at the heat-affected zone. Full article

Al/Mg dissimilar welds were successfully fabricated by refill friction stir spot welding using a grooved sleeve tool. Influences of sleeve penetration depth and rotational speed on the weld formation and mechanical performance were systematically evaluated in terms of welding parameter optimization, interfacial bonding mechanism, hardness distribution and welded joint strength. The results indicated that the success of joining Al alloy to Mg alloy significantly depends on tool sleeve penetration depth. The interfacial bonding mechanism compromised both metallurgical bonding and mechanical inter-locking. Intermetallic compound layers of Al₃Mg₂ and Al₁₂Mg₁₇ were formed at the Al/Mg interface. The thickness of the intermetallic compound (IMC) layer at the weld center increased from 20–30 μm to 40 μm when the rotational speed increased from 1000 to 2000 rpm. The minimum hardness was 80 HV in Al 7075 and 52 HV in ZEK 100; both were measured in the heat affected zone. The welded joint lap shear strength decreased, and the scatter increased with the increasing of rotation speed, whose maximum was 3.6 kN when the rotational speed was 1000 rpm. In addition, the failure mechanism was determined by tool rotational speed, and found to be interfacial failure under a rotational speed of 1000 rpm and nugget pullout under a rotational speed of 2000 rpm. Full article

Reciprocating piston pumps are widely used in various fields, such as automobiles, ships, aviation, and engineering machinery. Conventional reciprocating piston pump distributing flow (RPPDF) systems have the disadvantages of a loose structure and low volumetric efficiency, as well as affected positively by the operating frequency. In this paper, a novel rotating-sleeve distributing flow (RSDF) system is presented for bridging these drawbacks, as well as structurally improved to overcome the inoperable and challenging problems in oil intake and discharge found in the experiment. Moreover, the Singhal cavitation model specifically for the RSDF system and four-cam groove profiles (CGPs) is established. To find the most suitable CGP to reduce the RSDF’s cavitation, the cavitation of the RSDF system was investigated, combining with simulations by taking into account the gap among the rotating sleeve, the pump chamber, and experiments on four presented CGPs. Simulation results based on vapor volume fraction, cavitation ratio, and volumetric efficiency show that the linear profile’s cavitation is the weakest. Finally, the correctness of the simulation is verified through orthogonal experiments. This research is of great significance to the further development of the RSDF system; more important, it has great potential to promote the reform of the RPPDF method. Full article

Copper-clad aluminum rods are usually fabricated using hydrostatic extrusion, since during direct and indirect extrusion fracture of the copper sleeve is difficult to avoid. In this study, different die surface topographies and lubrication conditions were applied to improve the material flow during indirect extrusion of copper-clad aluminum rods. Thus, conic dies with different roughness (polished and sandblasted) and surfaces shapes (fine and coarse grooves) were tested. Additionally, the effects of a wax-graphite-based lubricant as well as a graphite-like carbon (GLC) coating of the die conic surfaces were investigated. The composite billets were made of aluminum EN AW-1080A cores and copper CW004A sleeves with an equivalent copper cross section of 0.24 of the total billet cross section. For all trials, an extrusion ratio of 14.8:1 and a conic die angle of 2α = 90° were chosen. Non-isothermal extrusion trials were carried out using a container at 330 °C and billet and tools at room temperature to reduce the flow stress ratio σ_Cu/σ_Al. The extruded composite rods’ integrity, surface quality, interface integrity, and equivalent copper cross section were analyzed. In addition, a visual inspection of the sleeve-die contact surface was performed. The results showed that the GLC coating proved to be unsuitable due to a lack of lubrication, which causes accumulated sleeve fractures and longitudinal grooves on the extruded rods. The best results were achieved with the combination of the sandblasted die surface and the wax-graphite-based lubricant, observing a uniform material flow without sleeve fractures. Full article