Tool selection and collision-free in 5-axis numerical control machining of free-form surfaces

The methodology of 5-axis cutter selection to avert collision for free-form surface machining by flat-end cutters is presented. The combination of different cutters is adopt aiming at short machining time and high precision. The optimal small cutter is determined based on the geometric information of the points where a cutter most probably collide with the machined surface. Several larger cutters are selected to machine the surface in order to find the interference-free area. The difference of machining time for this area between the optimal small cutter and the large cutters is calculated. The functional relationship between the machining time and the radius of a cutter is established, by which the optimal number of cutters is obtained. The combination of cutters, which possesses the minimum overall machining time, is selected as the optimal cutter sizes. A case study has demonstrated the validity of the proposed methodology and algorithms.

Selective laser melting of Fe-Ni-Cr layer on AISI H13 tool steel

An attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel was performed with selective laser melting.Fe-Ni-Cr coating was produced by experimental facilities consisting of a 200 W fiber laser which can be focused to 80 μm and atmospheric chamber which can control atmospheric pressure with N2 or Ar.Coating layer was fabricated with various process parameters such as laser power,scan rate and fill spacing.Surface quality and coating thickness were measured and analyzed.Three different surface patterns,such as typeⅠ,typeⅡand type Ⅲ,are shown with various test conditions and smooth regular pattern is obtained under the conditions as 10 μm of fill spacing,50-350 mm/s of scan rate and 40 μm of fill spacing,10-150 mm/s of scan rate.The maximum coating thickness is increased with power elevation or scan rate drop,and average thickness of 10 μm fill spacing is lower than that of 40 μm fill spacing.

Tool Materials Rapid Selection Based on Initial Wear

Based on a large amount of literature about tool wear research,873 tool wear curves are taken as samples,and statistical analysis is carried out to select the most suitable tool from all the tool materials suggested by the tool manufacturers. Statistical relationships between the initial wear and uniform wear periods are obtained. The results show that there is qualitative relationship between wear rate during initial wear period （WRIWP） and wear rate in uniform wear period （WRUWP） to certain extent. On this basis,a tool material rapid selection method based on the initial wear is put forward,and suitable tool materials for machining titanium alloy are selected. The experimental results indicate that this method is effective and useful. The new tool materials rapid selection can be used to select suitable cutting tool materials quickly before carrying out systematic machinability tests with the most suitable tool materials. The technology can be applied to doing the initial selection of cutting tool materials in either the machinability research or the workshop production.

Intelligent Tool Management Strategies for Automated Manufacturing Systems

With the increase in automation and use of computer control in machine tools, the number of cutting tools per machining setup is on the increase. On one hand, such multi-tool setups offer the advantages of reduced down-time and cost of production and require less space and in-process inventory, and on the other hand, require proper tool management for economic operations. A number of strategies have been devised to solve the tool selection problems and a number of tool replacement policies have been proposed in the past. These strategies have been solved in isolation, whereas, a comprehensive algorithm for proper selection of tools out of those available in the tool magazine for performing operation and for replacement of tools on failure/wear is necessary. In this paper, taking cue from the computer memory management policies, four tool selection strategies have been presented and their performance in tandem with various tool replacement policies has been studied. The effect of important parameters such as reduction of tool life due to regrinding, limited number of regrindings, catastrophic failures etc. have been considered. Cost has been computed for each combination of tool selection and replacement policy. Also, the number of machine stoppages has been worked out in each case. The results indicate that the combination of various selection strategies with suitable replacement policies affects the overall cost.

我国营商环境治理中的政策工具选择策略——基于51份政策文本的内容分析

建设良好的营商环境需要相应的政策工具。分析我国营商环境治理的政策工具选择,既要把握现实的政策,又要具有理论思维。本文基于政策工具选择理论,建立政策工具组合分析框架,运用内容分析法,对2014—2022年我国国家层面营商环境治理的51份政策文本进行编码分析。可以发现:我国营商环境治理中的政策工具选择表现为资源供给、需求整合及环境法制三类。资源供给类政策工具以政务服务提升作为主要手段,带动技术、资金等资源的投入。需求整合类政策工具以满足市场主体需求为主,将企业发展与市场塑造进行耦合。环境法制类政策工具强调强制性手段的合理运用,通过法规制度来规范营商环境的发展。未来,我国营商环境治理还需要不断推进政策工具创新,不断完善政策工具的具体类型,注重政策工具的科学运用。

慢性阻塞性肺疾病相关性疲劳评估工具的系统评价

目的对慢性阻塞性肺疾病(COPD)相关性疲劳特异性评估工具进行系统评价,为今后临床选择和开发高质量工具提供依据。方法检索PubMed、Web of Science、CINAHL、Embase、Cochrane Library、中国生物医学文献数据库(CBM)、中国知网(CNKI)、万方数据库和维普数据库中,所有关于COPD相关性疲劳特异性评估工具相关研究。检索时限为建库至2023年5月22日。使用“基于共识选择健康测量工具的标准(COSMIN)指南”对纳入工具的方法学及测量属性特征进行系统评价,综合评定证据等级并形成推荐意见。结果共纳入8个COPD相关性疲劳特异性评估量表,曼彻斯特COPD疲劳量表(MCFS)为A级推荐,修订版慢性病治疗功能评估—疲劳量表(MFACIT-F)、疲劳影响量表(FIS-25)、COPD和哮喘疲劳量表(CAFS)、疲劳评估工具(TFT)、中文修订版曼彻斯特COPD疲劳量表(MCFS-C)、中文修订版疲劳影响量表(FIS-C)、疲劳严重程度量表(FSS)为B级推荐。结论MCFS量表有高等证据支持内容效度、内部一致性和稳定性、中等证据支持结构效度,故暂被推荐使用,但适合我国的COPD相关性疲劳特异性评估工具仍有待进一步开发。

新型高强度钛合金切削刀具技术研究

针对TB18航空结构件在实际加工过程中加工效率低、刀具寿命短等问题,开展TB18材料与通用钛合金材料的切削过程对比试验,分析影响刀具切削性能的关键因素,并结合具体的加工需求,通过典型刀具选型改进、新型刀具研制和切削参数优化,提高TB18材料加工效率,延长刀具使用寿命。

盾构机刀盘结构和刀具布置设计研究

盾构施工具有安全可靠、经济性及适应性强等特点,广泛应用于公路、城市管廊、铁路及地铁等行业建设。为适应各种施工地质条件,盾构机的刀盘盘体结构有面板式、辐条式及辐板式等,文中对刀盘的开口率大小、刀具的选择与布置形式等进行了研究。

基于机器学习的刀具磨损状态智能预测方法研究

以刀具为研究载体,运用人工智能和智能优化等先进技术,成功实现了刀具磨损状态的智能预测。研究重点在于建立有效的刀具磨损状态预测方法,全面解析刀具磨损机理、形式及磨钝标准等关键信息。同时,构建了自采刀具磨损状态监测平台,以便收集并处理相关数据。在数据处理过程中,采用小波滤噪和EMD-Shannon能量熵进行特征筛选,构建出特征空间数据集,为后续构建预测模型提供坚实的数据基础。结合支持向量机分类算法和智能优化算法,构建出刀具磨损状态的智能预测框架。此框架不仅提高了预测精度,也为维护人员提供了强有力的工具,利于更好地进行刀具磨损状态的预测和维护工作。为增强实际应用价值,将所取得的成果整合至基于MATLAB GUI的刀具磨损状态智能监测原型系统,以图形界面方式呈现预测结果,使用户直观地了解和掌握刀具的磨损状态。结果表明,该方法具有高精度,刀具磨损状态的识别精度可达84%,为相关领域提供了可靠的技术支持。

scEpiTools: a database to comprehensively interrogate analytic tools for single-cell epigenomic data

Recent advances in single-cell sequencing technologies provide significant implications for understanding cellular heterogeneity,developmental biology,and disease mechanisms.To fully exploit the potential of these data,numerous tools have been proposed for upstream and downstream analyses.In the the single-cell RNA sequencing(scRNA-seq)community,scRNA-tools(Zappia et al.,2018)was proposed to help researchers navigate the plethora of tools by category.Since its inception,scRNA-tools has been widely used and its updated version further reveals trends in the field with over 1000 collected tools(Zappia and Theis,2021),providing a valuable guidance in selecting tools for analyses.

地方政府对我国全民健身政策再制定的工具选择与优化策略——基于“作用-效力-范围”的三维分析框架

均衡完善的全民健身政策工具组合能够有效引导、激励和推动全民健身高质量发展与中国式现代化体育强国建设。本研究基于全民健身政策工具视角,以30个省级行政区域的《全民健身实施计划(2021—2025)》政策文本为分析样本,采用内容分析法,从政策工具作用层面、效力维度和适用范围等方面深入挖掘“十四五”阶段我国地方全民健身政策工具的类型特征与选择偏向。笔者发现:地方性全民健身政策工具的系统性和互补性尚未得到足够重视,政策制定存在配置不均、内部衔接不足等问题,而供给层工具的使用过溢不仅未能发挥需求层工具的应有作用,规制性手段的频繁使用也极易挫伤市场积极性,战略性措施的过量配置还会阻滞预期目标的达成。因此以“均衡协调”为导向、“供需适切”为基础、“合理有效”为目标来完善和优化政策执行环境与实施路径将有助于全民健身政策的全面落实与效力保障。

钛合金高质量切削加工的刀具选择

本文综合分析了钛合金的成分与性能,探讨了高质量切削加工中的刀具选择策略,包括刀具材料的选择依据、常用刀具材料及其性能比较、钛合金加工的特殊要求与不同材质刀具的适应场合、刀具寿命等.

超高扩径不动管柱选层堵水工具及工艺

海上油气开发过程中,由于管柱特殊性,需通过?73.0 mm油管在?244.5 mm套管内实施选层堵水,堵水工具要求扩径比达到424%、耐压15 MPa。已有可膨胀桥塞和封隔器工具仅能实现最高扩径比350%、封堵底层。鉴于此,利用小管径连续管可穿过常规油管优势,基于伞形扩径原理,研制了过油管双伞单封式超高扩径不动管柱选层堵水工具,并针对工具特点,对堵剂和施工工艺进行了优选与优化。试验结果表明,选层堵水工具可有效通过最小内径为55.6 mm的?73.0 mm油管,在内径为217.3 mm的?244.5 mm套管内实现选层坐封,封堵后过流通道内径25.4 mm,可实现不动管柱情况下一趟钻完成选层堵水,具有扩径比大、不动管柱、不使用火工品、作业周期短、费用低等显著优势。研究结果可为水淹井开发提供一项新的技术手段。

博孜2402井钻井提速关键技术

目前塔里木博孜1区块部署的井多为五开井身结构,平均井深7000m以上。地质构造复杂,施工难度大,事故复杂频发,周期普遍在400d以上。该区块吉迪克组、库姆格列木群盐层段以及目的层事故频发成为区块钻井难题,尤其是上部巨厚砾石层严重制约区域资源高效勘探开发,实钻表现为机械钻速慢、单只钻头行程进尺低、因憋跳钻引发井下钻具事故频发。博孜2402井从井身质量优化、钻头选型技术、钻具组合优化技术、钻井液体系优选、盐层卡层技术等方面着手,形成了博孜2402井钻井提速关键技术,该井最终以钻井周期253.88d,钻完井周期303.88d,创博孜1区块钻完井周期记录,博孜2402井关键钻井技术,可为博孜1区块钻井提供技术支持,建议进行推广。

政策工具视角下我国普通高中新课程政策文本分析

文章基于政策工具理论,采用内容分析法,从政策工具类型和新课程政策内容要素两个结构维度,对2017—2021年国家层面颁布的14份与普通高中新课程密切相关的政策文本进行量化分析。研究发现,普通高中新课程政策体系基本形成,但在工具选择上存在问题:使用比例失衡而权威型工具依赖较强;新课程政策内容要素差异明显,与政策工具拟合度不高;政策工具存在制度惯性,工具选择基于惯性思维等。为此,在今后新课程政策推进过程中,需要构建新课程政策工具使用的协同机制,优化新课程政策内容要素维度结构布局,构建科学合理的新课程政策工具选择机制。

数控车床加工的产品质量控制

使用数控车床在加工过程中,经常会碰到尺寸精度不稳定、位置精度不稳定、表面粗糙度不稳定等产品质量难以控制的问题,甚至会碰到不明原因的振刀、断刀、缠屑、零件变形等问题,本文主要从三个大方面阐述数控车床加工的产品质量控制方法,数控车床设备,工艺方法、刀杆、刀片的选择和切削用量。

富水灰岩地层土压平衡盾构施工技术

本研究以某盾构区间在富水岩溶高强度灰岩地层施工为实例,针对地下水丰富、灰岩硬度高、岩溶强烈发育等不利地质条件,通过优化掘进参数、选择合适的刀具、改良渣土等一系列技术措施,成功解决了盾构掘进过程中的技术难题。在施工中,通过优化刀具选型,有效延长了刀具的使用寿命,提高了掘进效率。此外,对渣土进行改良处理,进一步减少了掘进过程中的阻碍和风险。本研究提出了一套适用于富水岩溶高强度灰岩地层的盾构掘进参数,这些参数在保证施工安全的同时,显著提升了施工效率,并增加了经济效益,对地铁建设领域的技术创新和发展具有重要意义。

异形圆柱夹具设计与加工研究

现代化产品生产规模逐渐增加,加工生产期间得到的零件常常属于不规则的形式,面对这样的零件应选取匹配的夹具,从而更好地符合铣削加工的要求,生产中经常出现异形圆柱零件,为了选用专门的夹具完成夹持工作,主要围绕夹具展开,基于异形圆柱,分析夹具的设计、加工环节选用的方式,促使相关生产加工能够更加高效,提升零件的加工精度。

数控刀具技术与应用探析

数控刀具是切削加工的基础工艺装备,在制造过程中与数控机床相互配合承载不同的加工工艺,共同完成材料切削加工。针对数控刀具的选用,探讨了选用要点,并以具体数控车加工为例进行了刀具的选用,以促进数控刀具更好地发展与应用。

Developing potent PROTACs tools for selective degradation of HDAC6 protein

Dear Editor, Histone deacetylases (HDACs) are a family of enzymes that remove acetyl groups on histone and non-histone proteins, thereby playing a vital role in the modulation of gene expression and protein activity. Eighteen HDACs have been identified in human and subdivided into four classes including I, II (Ila, lib), III and IV (Seto et al., 2014). Among them, HDAC6 is a unique lib HD AC with dominant cytoplasmic localization and two functional catalytic domains. Besides the functions for deacetylation of histone, and modulation of a-tubulin, HSP90 and cortactin, HDAC6 also participates in protein trafficking and degradation, cell shape and migration (Valenzuela-Fernandez et al., 2008). The deregulation of HDAC6 is related to various diseases, such as neurodegenerative diseases, cancer and pathological autoimmune response (Batchu et al., 2016). Hence, it is especially important for directly controlling cellular HDAC6 protein levels to achieve therapeutic purposes. The traditional approaches of red u ci ng cellular protein levels mainly rely on genetic modifications, such as RNA interference, transcription activator-like effector nucleases, recombination-based gene knockout and clustered regularly interspaced short palindromic repeats (CRISPR-Cas9)(Boettcher et al., 2015). However, these approaches have failed to a certain degree to achieve acute and reversible changes of gene function. Furthermore, the complications of potential genetic compensation and/or spontaneous mutations arising in geneknockout models may lead to misinterpretations (Davisson etal., 2012;El-Brolosy etal., 2017). Therefore, it is urgent for developing a rapid, robust, and reversible approach to directly modulate HDAC6 protein levels.