Novel Environmentally Friendly Manufacturing Method for Micro-Textured Cutting Tools

Changping Li,Xinyi Qiu,Zhen Yu,Shujian Li,Pengnan Li,Qiulin Niu,Rendi Kurniawan,고태조 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.1

Surface texturing on cutting tools has a great influence on reducing the friction force between tool and chip interfaces. In this study, a grinding method was developed to fabricate micro-groove textures on cutting tools using a special diamond grinding wheel on the tool rake face. A comparative experiment was done using a laser and other grinding method to fabricate micro-grooves. The developed grinding method does not produce harmful gases, it is environmentally friendly, and it fabricates groove textures with high efficiency and quality. Various micro-grooves with depths of 30–90 μm, groove pitches of 0.5–1 mm, and groove angles of 30–60 o were made on the rake faces of non-coated end-mill tools using the developed grinding method. Milling experiments on aluminum alloy (Al6061-T6) and tool steel (SKD11) with non-water-soluble coolant were carried out using the textured tools, and the cutting force and tool wear were investigated. In most cases, the cutting force produced by the micro-grooved tools is significantly reduced. In addition, the wear resistance of the micro-groove cutting tool is better than that of a conventional cutting tool, and there is no chipping.

Hole exit damage and tool wear during the drilling of CFRP with a double-point angle drill

Pengnan Li,Xinyi Qiu,Changping Li,Qiulin Niu,Anhua Chen,고태조 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.5

The control of hole exit damage and hole wall quality poses a considerable challenge during the drilling of carbon fiber-reinforced plastic (CFRP). This study aims to study the effect of the cutting edge type on the aforementioned issues. First, a comparative study between hole exit damage caused by a twist drill and a double-point angle drill was conducted to investigate the influences of the chisel, principal, and secondary cutting edges on hole exit damage. The maximum damage ring caused by the double-point angle drill is smaller than that caused by the twist drill because the drop speed of the cutting force in the secondary cutting edge drill during the exit stage of the double-point angle drill is less than that of the twist drill. Then, the double-point angle drill was used to determine the effects of tool wear on thrust force and hole wall damage. Outer corner wear and flank wear were investigated, and hole wall damage mechanisms were discussed. The damage of missing fibers does not worsen with an increase in tool wear, but the damage of fiber pullout becomes more serious due to increased cutting force. Consequently, a double-point angle drill bit is preferable for drilling holes on CFRP.

Numerical Modelling of Air-Water Flows over a Stepped Spillway with Chamfers and Cavity Blockages

Shicheng Li,James Yang,Qiulin Li 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.1

Owing to effective aeration and energy dissipation, a stepped spillway is commonly used in a roller-compacted concrete (RCC) dam. However, its complex air-water flow features are far from being fully understood. Roughness density, step and cavity shapes are essential parameters. Numerical simulations are carried out to investigate their effects on hydraulic properties. In combination with the realizable k-ε turbulence model, the two-phase Mixture Model is used. The results indicate higher air concentrations for the spillway with rounded steps than the ones with trapezoidal steps; the roughness density and cavity shape show no observable effects on the aeration performance with cavity blockages. The characteristic air-water velocity for the trapezoidal steps layout is larger than that for the rounded steps. However, neither layout is sensitive to the roughness density; the velocity results for trapezoidal cavity and rounded cavity cases are almost independent of the roughness density. The velocity for all cases exclusive of trapezoidal steps increase with an increase in roughness density. The min. and max. pressures on the trapezoidal steps are slightly larger than those on the rounded steps; they increase with an increasing roughness density. The cavity shape and roughness density do not evidently influence the extreme pressures. Compared with the conventional step layout, chamfering the step edges slightly enhance the energy dissipation; partially blocking the cavities do not lead to any substantial change. In addition, the energy loss is not clearly related to the roughness density and step edge/cavity shape.

Failure analysis of R-regions of CFRP hat-shaped structure under pull-off load

Chen Rong,Li Shujian,Tae Jo Ko,Li Pengnan,Jiang Yong,Li Changping,Niu Qiulin 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

As a kind of typical structure, the hat-shaped structure (HSS) is widely used in carbon fiber reinforced plastics (CFRP) aircraft parts. In this work, a scheme of filling fillers and adding reinforcing plies in R-regions was proposed to strengthen the R-regions of HSS. Moreover, the force analysis of R-region with or without strengthening in R-region under pull-off load was presented. A finite element model was developed to study the failure behavior of Rregions. A series of HSS samples were fabricated by co-curing process. The pull-off tests of HSS were conducted to validate the model, and the failure mechanism of R-regions was further studied by characterizing the macro-micro structure of R-regions in HSS under pull-off load. Results showed that the structural bearing capacity of HSS can be improved by strengthening in R-regions. After strengthening in R-regions, the pull-off load was borne by multiple interfaces, and the interlaminar interface pull-off strength can increase by 38.8 %.

Tool life evaluation of CFRP drilling with three kinds of drill

Xinyi Qiu,Pengnan Li,Changping Li,Qiulin Niu,Shujian Li,Tae Jo Ko,Lingyan Tang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

Serious tool wear in CFRP drilling is one of the key problems to be solved urgently. Firstly, a suitable indirect evaluation index of tool life is selected according to the literature. The critical delamination force was obtained by blind hole pushing experiment. Then, tool wear experiments were carried out with double point angle drill, stepped drill and reverse edge compound drill to analyze the variation rules of the thrust force, exit burr, exit delamination and tear with tool wear. Threshold values of exit delamination, tearing and critical thrust force were compared with each evaluation index one by one to study the causes of drills failure. The results indicated that the maximum tool wear position was the outer corner. Among the three types drills, the thrust force, delamination factor and burr angle of the reverse edge compound drill are smaller. The double point angle drill fails due to the excessive thrust force, while the stepped drill and the reverse edge compound drill fail due to the hole exit delamination exceeding the threshold. The number of drilled holes of the reverse edge compound drill is 100 % and 25 % higher than that of the double point angle drill and the stepped drill, respectively. Therefore, the reverse edge compound drill is suitable for drilling CFRP.

Tool Wear in Longitudinal-Torsional Ultrasonic Vibration Assisted Drilling of CFRP/Ti Stacks and Its Influence on Drilling Quality

Chunhao Wang,Pengnan Li,Shujian Li,Xinyi Qiu,Changping Li,Qingquan Jiang,Qiulin Niu,Tae Jo Ko 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.1

Longitudinal-torsional ultrasonic vibration assisted drilling (LTUVD) has received extensive attention as a new machining technology in recent years. Especially for the stacks structure similar to carbon fiber reinforced polymer/titanium alloy material (CFRP/Ti6Al4V), it has more significant machining advantages. However, the effect mechanism of longitudinal-torsional ultrasonic vibration (LTUV) on tool wear, the tool wear condition in LTUVD machining and its influence on machining quality are not clear. In this work, the effect of LTUV on the tool wear of CFRP/Ti stacks was analyzed, and the tool wear of CFRP/Ti stacks and its effect on the entrance, interface and hole wall were investigated by drilling experiments under LTUVD condition. The analysis demonstrated that LTUVD can reduce tool wear by reducing the force and temperature during CFRP/Ti stacks drilling. The typical characteristics of LTUVD drill wear were the reduction of the flank face width, the adhesion of Ti to the tool, the blunting and the fracture of the cutting edge. The worn tool shows different wear characteristics in different parts. Spindle speed is one of the key factors that affect the wear rate of the typical parts, such as chisel edge, outer edge corner and main cutting edge. The mean damage factor of the entrance and interface of the 17–20 holes drilled by LTUVD were 11.5% and 8.7% higher than those of the 1–4 holes respectively. As the tool wear intensifies, the hole wall of CFRP produced more pits and the flatness decreased. The hole wall roughness increased by 30.9% when the 17–20 holes were drilled compared with the 1–4 holes.

A novel and environmentally friendly SO4 2- /CeO2 catalyst for the selective catalytic reduction of NO with NH3

Qiulin Zhang,Jinhui Zhang,Zhongxian Song,Ping Ning,,Hao Li,Xin Liu 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-

The SO42 /CeO2 catalyst showed excellent catalytic activity and remarkable resistance to H2O and SO2for the selective catalytic reduction of NO with NH3. The SO42 /CeO2 catalyst with 2.5 wt.% SO42 contentexhibited more than 90% of NO conversion at 229–485 8C. The characterization results revealed that theSO42 species were highly dispersed on the surface of CeO2 in the SO42 /CeO2 catalyst. Moreover, theaddition of SO42 into CeO2 obviously increased the surface Lewis and Brønsted acid sites, and it wasfound that only stable (1 1 1) lattice planes of CeO2 can be observed on the SO42 /CeO2 catalyst.

Genetic localization of the SPC gene controlling pod coiling direction in Medicago truncatula

Xiaocheng Yu,Qiulin Qin,Xia Wu,Dandan Li,Shengming Yang 한국유전학회 2020 Genes & Genomics Vol.42 No.7

Background Handedness in plants introduced by helical growth of organs is frequently observed, and it has fascinated plant scientists for decades. However, the genetic control of natural handedness has not been revealed. In the model legume Medicago truncatula, pods can be coiled in a clockwise or anti-clockwise manner, providing a model for genetic analysis of plant handedness. Objective We aimed to localize the Sense of Pod Coiling (SPC) gene controlling pod coiling direction in M. truncatula. Methods Linkage analysis was used with a biparental population for fine mapping of the SPC gene. The genome sequence of M. truncatula Mt4.0 was used for marker identification and physical mapping. Single nucleotide polymorphisms (SNPs) between the parental lines were converted to CAPS (cleaved amplified polymorphic sequences) markers. Genetic map was constructed using the software JoinMap version 3.0. Gene predication and annotation provided by the M. truncatula genome database (http://www.medic agoge nome.org) was confirmed with the programs of FGENESH and Pfam 32.0, respectively. Quantitative reverse transcription PCR (qRT-PCR) was used to analyze the relative expression levels of candidate genes. Results The genetic analysis indicated that the anti-clockwise coiling is dominant to clockwise and is controlled by the single gene, SPC. The SPC gene was delimited to a 250 kb-region on Chromosome 7. Total of 15 protein-coding genes were identified in the SPC locus through gene annotation and sequence analysis. Of those, two genes, potentially encoding a receptor-like kinase and a vacuolar cation/proton exchanger respectively, were selected as candidates for the SPC gene. Conclusions The result presented here lay a foundation for gene cloning of SPC, which will help us to understand the molecular mechanisms underlying helical growth in plant organs.

Facile Synthesis of Ag/ZnO Hollow Microspheres with Enhanced Photocatalytic Performance under Simulated Sunlight Irradiation

Lifeng Cui,Qiulin Zhang,Chaochuang Yin,Shifei Kang,Zhigang Ge,Qineng Xia,Yangang Wang,Xi Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

Water pollution caused by intensive use of organic dyes has become an increasingly serious problem recently. Green and efficient processes are desperately needed to remove persistent organic pollutants from waste waters. Herein, Ag nanoparticles loaded ZnO hollow microspheres were synthesized through a simple solvothermal method and used as a photocatalyst for dye degradation. The calculated band gap of Ag/ZnO — 5% (2.97 eV) is much narrower than that of pure ZnO (3.37 eV). The obtained Ag/ZnO samples show a remarkable photocatalytic activity in photodegradation of Rhodamine B (RhB) under simulated sunlight irradiation. The degradation efficiency of RhB for Ag/ZnO — 5% is 98.8% after 100 min irradiation while only 52.8% degradation rate is obtained over pure ZnO. The enhancement is attributed to the exposed active ZnO (001) plane and the surface plasmon resonance (SPR) effect of Ag nanoparticles that promote the separation of photogeneated electrons and holes.

New Compound Drill Bit for Damage Reduction in Drilling CFRP

Xinyi Qiu,Pengnan Li,Changping Li,Qiulin Niu,Anhua Chen,Puren Ouyang,Tae Jo Ko 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.1

This paper focuses on finding a suitable drill bit for drilling Carbon Fiber Reinforced Plastic (CFRP). The drilling characteristics of the dagger drill, the double point angle drill, and the candle stick drill are studied. The results show that the side edge has poor ability to remove burrs, and the tip structure of the outer corner of the candle stick drill can greatly reduce the entry damage. However, the outer corner small tip structure of the candle stick drill cannot effectively remove the uncut fiber around θ = 0° of hole exit. The long secondary cutting edge of the dagger drill makes a small thrust force at the drilling exit stage and reduces the dropping speed of the thrust force, leading a lower impact on the laminate bottom. Then, a new tool is developed for drilling CFRP based on the advantages of the three kinds of drill bits. The drill has a long secondary cutting edge, a small tip diameter and a small tip structure of the outer corner. And its drilling characteristics are analyzed. The result shows that the new compound drill bit can effectively remove fibers and reduce thrust force at the drilling exit stage, form burr-free and small delamination hole. The drill reduces the waste of CFRP in manufacturing process since the exit damage is reduced substantially, which is in line with the concept of green manufacturing.