玻化砖抛光用金刚石磨料的耐磨性及磨削性研究

本文通过实验 ,对玻化砖抛光用金刚石磨料在不同工作压力和磨削速度下的磨削情况进行了研究 ,获得了磨料磨损量及砖磨削量随载荷和磨削速度变化的趋势 ,从而确定了该种磨料在玻化砖抛光生产中的合适的工作条件 :磨削速度和工作压力。

高性能难加工材料可磨削性研究进展

高性能难加工材料在高端制造业中的应用越来越广泛,关键零部件的精度要求极高,而材料的可磨削性差,对磨削加工工艺提出了严峻挑战。为了提高难加工材料磨削表面完整性,降低砂轮磨损,国内外学者开展了大量研究。全面回顾了难加工金属材料、硬脆材料以及复合材料可磨削性的国内外研究进展,包括工件表面完整性、砂轮堵塞与磨损、磨削颤振以及改善可磨削性的先进技术4个方面。对不同类型难加工材料可磨削性的特点及共性问题展开了讨论,总结了各类难加工材料加工损伤的成因,指出改善难加工材料可磨削性的主要思路是降低磨削力和磨削温度。分析了磨削力和磨削热的来源以及对表面完整性和砂轮磨损的影响,提出了基于“节源”和“开流”思想降低磨削力和磨削温度的工艺策略,并对难加工材料高质高效加工方法进行了展望,指出高性能砂轮及其修整技术、高效冷却润滑技术、多能场复合磨削技术以及超高速磨削技术的不断发展,都有利于解决难加工材料的高质高效加工难题。

丝锥用HYTV3高性能高速钢的耐磨性和可磨削性评价

介绍了河冶科技自主研发的丝锥用3V级HYTV3高性能高速钢与国外某厂3V级高速钢的性能。通过合金化设计、精准化工艺控制,HYTV3高速钢获得细小均匀的MC碳化物组织。通过改变磨削加工类型、砂轻材质、砂轮转速参数,对比了M2、HYTV3、M3、GV3、M35五种材质的耐磨性和可磨削性,证明HYTV3高速钢在保持良好耐磨性的同时具有优异的可磨削性。

大规格陶瓷板均匀性磨削机理研究

针对大规格陶瓷板磨削均匀性差,加工效率低的现状,本文提出大规格陶瓷板均匀性磨削机理及实现方法,采用均匀性磨削区域平移到非均匀性磨削区域,提高大规格陶瓷板板面均匀性。并通过仿真验证了所提大规格均匀磨削理论的正确性。研究结果还得出磨头并排磨削不仅提高均匀性还提高加工效率。

早期微创性磨削痂治疗面部深二度烧伤的临床观察

研究早期微创性磨削痂治疗对于面部深二度烧伤的治疗效果。方法:选择医院在2019年1月-2021年1月期间治疗的面部深二度度烧伤患者60例,烧伤程度的判断按照临床标准进行,确定为Ⅱ度烧伤。按照治疗方案的不同分为对照组和试验组,各30例。所有患者入院后都提供0.1%苯扎氯氨溶液冲洗创面,之后为对照组提供1%磺胺嘧啶银混悬液暴露治疗,为试验组提供早期微创性磨削痂治疗。疗程设定为3周,然后分别统计治疗后1、2、3周的创面愈合率、创面好转率以及创面愈合质量。结果:治疗后1、2、3周后,两组的创面愈合率、创面好转率数值均不断提高,且试验组要高于对照组,对比P<0.05;相比治疗前,治疗后1、2、3周中,两组的创面炎症反应评分均不断降低,且试验组要低于对照组,对比P<0.05;试验组在创面愈合质量方面,疗效明显优于对照组,对比P<0.05。结论:针对面部深二度烧伤,使用早期微创性磨削痂治疗,相对来说有更好的效果,患者的创面愈合率和好转率更高,且创面炎症反应评分不断降低,创面恢复质量良好,整体疗效比较显著。

Q开关1064nm Nd:YAG激光照射对大鼠皮肤中羟脯氨酸含量、皮肤厚度和FGF-1表达的影响

目的:确定Q开关1064 nm Nd:YAG激光非磨削性嫩肤对大鼠真皮胶原增生和成纤维细胞生长因子-1(FGF-1)表达的影响。方法:用Q开关1064 nm Nd:YAG 激光照射大鼠脱毛的背部皮肤,每3天1次,连续4次。照射后第14天和30天分别取大鼠皮肤测量真皮厚度并检测羟脯氨酸含量,免疫组化法检测FGF-1的表达。结果:激光照射后第14天大鼠皮肤真皮厚度明显增加,胶原纤维束粗大、密集,皮肤中羟脯氨酸含量增加,与对照组相比有显著性差异(P<0.05)。免疫组化显示FGF-1在激光照射后第14天表达明显上调。照射第30天时,真皮厚度和羟脯氨酸含量下降,FGF-1表达下调。结论:FGF-1在激光非磨削性嫩肤治疗大鼠皮肤中表达上调,可能导致真皮内胶原增生密切相关。

STUDIES ON MAGNETIC ABRASIVE MACHINING

This paper deals with the machining process using magnetic abrasives. Using an apparatus designed and made, a series of experiments are carried out, where the workpiece is cylindrical and the magnetic abrasives used are mainly Fe and Al 2O 3, for investigating the effects of machining time, working gap, rotating speed of workpieces, magnetic flux density on machining efficiency and surface roughness. At the end of this paper, the machining mechanism is also discussed.

Integrity of grinding face-gear with worm wheel

Aiming at the issue of the grinding integrity of face-gear with worm wheel, the envelope mathematical model of shaper, worm wheel and face-gear is established based on theories of differential geometry and gear mesh. The judgment of completely grinding the face-gear with the avoidance of singularities is established, and the mathematical expression to show the reason why singularities appear is derived, through the research on the surface contact area and singularity rules of the worm thread surface. The disadvantage of current face-gear grinding method that only part of the working surface of the face-gear can be covered is analyzed and the influence of coefficient of judgment is studied through changing the design parameters.

Research on the cutting performance and the wear mechanism of the cermet cutter in high speed turn-milling

When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble cooling fluid, the wear performance of the cermet cutter is bad, and does not adapt to the requirements of machining. However, when machining D60 by high speed turn-milling is under dry conditions, the wearing performance of the cermet cutter is very good and the cutting time lasts almost 3 hours. The wear mechanism of the cermet cutter under the water soluble cooling fluid is different from the dry condition. With the water soluble cooling fluid, a great deal of little chap units are formed since high frequency alternates heat stress. The crash and desquamate of these chap units is the main cause of the cutter wearing. Under dry cutting conditions, it is the main cause of cermet cutter wear in the felting phase intenerating causing rigid phase grains to fall.

Effect of PCBN cutting tools wear on surface integrality in high-speed hard turning

In this paper, the effect of of flank wear polycrystalline cubic boron nitride （PCBN） tools on residual stresses, white layer and roughness of machined workpiece surfaces is studied. Experimental results indicate that with the increase of the tool wear, the surface of the machined workpiece tends to generate tensile residual stresses, and white layer becomes clearly thicker and uneven on the workpiece surface. The effect of the flank wear on the surface roughness is less within some range of flank wear value. The results show that it is possible to produce ideal surface integrality levels by controlling the tool flank wear.

Thermo-mechanical properties of bowl-shaped grinding wheel and machining error compensation for grinding indexable inserts

In order to meet the technical requirements of grinding the circumferential cutting edge of indexable inserts, thermo-mechanical properties of bowl-shaped grinding wheel in high speed grinding process and the influence of dimension variations of the grinding wheel on machining accuracy were investigated. Firstly, the variation trends of the dimension due to centrifugal force generated in different wheel speeds were studied and the effect of stress stiffening and spin softening was presented. Triangular heat flux distribution model was adopted to determine temperature distribution in grinding process. Temperature field cloud pictures were obtained by the finite element software. Then, dimension variation trends of wheel structure were acquired by considering the thermo-mechanical characteristic under combined action of centrifugal force and grinding heat at different speeds. A method of online dynamic monitoring and automatic compensation for dimension error of indexable insert was proposed. By experimental verification, the precision of the inserts satisfies the requirement of processing.

Tribological performance of TiAlSiN and TiAlCrN/TiAlN coating blades

A new laboratory evaluation method for the coating blade was developed, and the tribological properties of coating blades with different Ti-based coatings were studied by UMT-2 tribometer. Comparison between the areas of scratches before and after the cutting experiment was used to evaluate the cutting performance of the blades. Results showed that friction coefficient of TiA1CrN/TiA1N coating was significantly lower than that of TiA1SiN coating. Analysis of the worn surface revealed that the TiA1SiN and TiAICrN/TiA1N coatings in the dry turning process exhibited sign of inhornogeneous adhesive wear and abrasive wear. TiA1CrN/TiA1N coating has a longer working life and better anti-wear property because of its duplex coating.

Cutting force and its frequency spectrum characteristics in high speed milling of titanium alloy with a polycrystalline diamond tool

In this paper, a series of experiments were performed by high speed milling of Ti-6.5Al-2Zr-1Mo-1V (TA15) by use of polycrystalline diamond (PCD) tools. The characteristics of high speed machining (HSM) dynamic milling forces were investi- gated. The effects of the parameters of the process, i.e., cutting speed, feed per tooth, and depth of axial cut, on cutting forces were studied. The cutting force signals under different cutting speed conditions and different cutting tool wear stages were analyzed by frequency spectrum analysis. The trend and frequency domain aspects of the dynamic forces were evaluated and discussed. The results indicate that a characteristic frequency in cutting force power spectrum does in fact exist. The amplitudes increase with the increase of cutting speed and tool wear level, which could be applied to the monitoring of the cutting process.