矿物湿法超细磨矿中助磨剂的作用效应及其程度的研究

通过考察硬脂酸钠对重质碳酸钙－水矿浆粘度的影响和因硬脂酸钠在重钙表面吸附而导致的颗粒表面自由能的变化以及由此产生的对湿式搅拌磨细磨重质碳酸钙磨矿效果的影响,研究了助磨剂的各种作用效应及其程度。结果表明,助磨剂对矿物湿法细磨的助磨作用是改善矿浆流变性和吸附降低颗粒表面自由能两种效应综合的结果,其中前一作用较强。     

卧式搅拌磨机制备黄芪超微粉

为探索卧式搅拌磨机制备黄芪超微粉的可行性,将卧式搅拌磨机改造为循环粉磨冷凝装置,探讨粉磨介质类型、粉磨介质尺寸、介质充填率、搅拌速率、粉磨时间对粉磨产品粒度特性的影响。结果表明：在粉磨介质氧化铝陶瓷球的粒径为1 mm、介质充填率为45%、搅拌速率为2 250 r/min、粉磨时间为20 min的条件下,可以获得d₉₀为10.46μm和d₅₀为2.95μm的黄芪超微粉,并且产品粒度均匀,无灼烧、氧化等现象,黄芪的有效组分得到保护。     

金红石型钛白粉的湿法超细研磨实验研究

以卧式砂磨机为超细研磨设备,研究研磨介质填充率、磨机转速、矿浆中粉体含量、助磨剂添加量、研磨时间对金红石型钛白粉超细研磨效果的影响。结果表明,在介质填充率为70%,磨机转速为2 250 r/min,矿浆中粉体质量分数为50%,添加助磨剂质量分数为0.4%的条件下,金红石型钛白粉超细研磨20 min制得钛白粉的粒径d50、d97分别可达0.48、1.07μm。     

助磨剂对泡沫玻璃配合料粉磨效率的影响

采用干法粉磨工艺,选取丙三醇、硅酸钠、三异丙醇胺、三乙醇胺、木质素磺酸钠5种助磨剂,研究助磨剂对泡沫玻璃配合料粉磨的影响;改变助磨剂掺量,以粉体粒度评价助磨剂对配合料粉磨效率影响。结果表明:随着助磨剂掺量的增大,粉磨效率提高,但是粉磨效率存在一个极值,该极值与助磨剂的种类和用量相关;泡沫玻璃配合料的最佳助磨剂为三乙醇胺,最佳掺量(质量分数)为0.04%,粉磨后平均粒径为13μm,比未用助磨剂的配合料平均粒径减小43%。     

单体助磨剂对硅酸盐水泥性能的影响

以三异丙醇胺、三乙醇胺、丙二醇、乙二醇、山梨醇和二乙二醇6种不同的醇及醇胺类单体为助磨剂,添加的质量分数均为0.04%,粉磨30 min,分析粉磨后的水泥颗粒形貌、比表面积、筛余量、粒径分布以及3、28 d水泥试块的强度等。结果表明,6种助磨剂均能改善粉磨效率,提高胶砂强度。     

超声波对氟金云母剥离细化作用的研究

研究了超声波对云母细化作用效果的影响因素,通过对颗粒浓度、分散介质、超声时间、超声功率以及助磨剂等因素的剥离细化试验。研究结果表明:颗粒浓度为18.7%、超声时间和超声功率分别为60min和300W,添加了极少量的助磨剂时超声波对云母的剥离细化效果最好。云母粉的比表面积从3.59m2/g增至7.69m2/g,d50从16.73μm降至11.28μm。在云母剥离细化过程中,超声波的空化作用起主导作用。     

机械力化学改性钙基膨润土提高注浆材料的稳定性

利用高能球磨机,通过机械力作用和机械力化学作用分别对钙基膨润土进行改性,通过X射线衍射仪、扫描电子显微镜、激光粒度仪及Zeta电位仪对改性膨润土进行表征,然后将经机械力作用和机械力化学作用改性的膨润土分别加入水胶比为1的水泥浆。结果表明:经机械力化学作用改性后,膨润土的d(001)由未改性的1. 52 nm变化为1. 27 nm,其层间钙离子被钠离子置换,D50(样品颗粒累计50%点的直径)由未改性的13. 5μm降低到0. 64μm,Zeta电位由未改性的-5. 5 mV变为-66. 3 mV,可达到粒度减小和表面改性的双重目的。经球磨机研磨45 min后的膨润土可使水泥浆静置2 h的泌水率降低至3. 97%,将焦磷酸钠与膨润土湿磨15 min后复合物可使水泥浆的泌水率降低至3. 64%。     

球磨与搅拌磨粉磨矿渣粉的微观形貌特性

采用小型球磨和搅拌磨对矿渣粉进行粉磨实验,运用扫描电镜样品制备技术,对球磨和搅拌磨不同粉磨阶段的矿渣粉进行微观形貌特征研究,分析不同粉磨方式粉磨过程中矿渣粉颗粒的微观形貌变化规律。结果表明,随着粉磨时间的延长,矿渣粉颗粒群的形状指数、扁平度、棱角度和表面粗糙度均减小,圆度系数增大;球磨和搅拌磨粉磨矿渣粉颗粒的微观形貌存在较大差异,粉磨时间相同时,搅拌磨粉磨矿渣粉颗粒的微观形貌优于球磨粉磨的。     

助磨介质作用下旋窑熟料微细化过程的研究

研究了助磨剂作用下旋窑熟料的微细化过程。结果表明 ,助磨剂在不同粉磨阶段的作用机理不同 ,在相同的粉磨时间下助磨剂提高了粉磨细度 ,改善了物料的颗粒分布 ,改变了颗粒形貌 ,还改变了粉磨物料的微观结构 ,加剧了物料的晶格畸变、晶格缺陷及无定形化 ,加速了物料结构中化学键的破坏 ,尤其是C3S矿物中Si—O键的断裂 ,从而增加物料的反应活性     

水泥助磨剂在水泥粉磨中的重要作用

水泥助磨剂可以很好地改善粉磨条件、提高粉磨效率、大大降低粉磨能耗,同时还具有优化水泥颗粒级配、增加水泥的抗压抗折强度、减少温室气体的排放、提高水泥中混合材的掺量等优点.系统阐述了助磨剂在水泥粉磨中的重要作用,包括助磨剂的作用机理、分类、所带来的经济效益、发展历程以及存在的问题等.     

Continuous generating grinding method for beveloid gears and analysis of grinding characteristics

Continuous generating grinding has become an important gear processing method owing to its high efficiency and precision. In this study, an adaptive design model is proposed for the continuous generation of beveloid gears in common gear grinding machines. Based on this model, a method for determining the installation position and grinding kinematics is developed alongside an analytical meshing model for grinding contact trace and derivation of key grinding parameters. By combining these aspects, a general mathematical model for the continuous generation of beveloid gears is presented, comprising the entire grinding process from worm wheel dressing to the evaluation of grinding deviation. The effects of the worm and dressing wheel parameters on the grinding deviation were analysed, facilitating the development of an approach to improve the grinding accuracy. The presented procedure represents a novel design method for the continuous generation of beveloid gears in common gear grinding machines, facilitating the appropriate selection of worm and dressing wheel parameters.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00388-z     

Study into grinding force in back grinding of wafer with outer rim

Back grinding of wafer with outer rim (BGWOR) is a new method for carrier-less thinning of silicon wafers. At present, the effects of process parameters on the grinding force remain debatable. Therefore, a BGWOR normal grinding force model based on grain depth-of-cut was established, and the relationship between grinding parameters (wheel infeed rate, wheel rotational speed, and chuck rotational speed) and normal grinding force was discussed. Further, a series of experiments were performed to verify the BGWOR normal grinding force model. This study proves that the BGWOR normal grinding force is related to the rotational direction of the wheel and chuck, and the effect of grinding mark density on the BGWOR normal grinding force cannot be ignored. Moreover, this study provides methods for reducing the grinding force and optimizing the back thinning process of the silicon wafer.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00316-z     

SiC_p/Al超声振动辅助磨削砂轮选择方法研究

使用电镀金刚石砂轮、钎焊金刚石砂轮、陶瓷结合剂烧结金刚石砂轮和树脂结合剂烧结金刚石砂轮超声振动辅助磨削铝基碳化硅(SiC_p/Al),将砂轮磨损、材料去除、磨削表面形貌进行了对比分析,给出SiC_p/Al超声振动辅助磨削砂轮的选择方法。结果表明,陶瓷结合剂烧结金刚石砂轮在超声振动辅助磨削SiC_p/Al的过程中具有磨削过程平稳、材料去除均匀、工件表面质量好、砂轮磨损小的特点,是磨削SiC_p/Al的理想砂轮。本文的研究工作作为SiC_p/Al磨削工艺研究领域的一个方面,对SiC_p/Al磨削过程中砂轮的选择研究具有一定的指导意义。     

立式玻璃磨边机砂轮离心振动特性分析

针对立式玻璃磨边机砂轮架的结构特点,建立其动力学模型及系统运动微分方程,导出砂轮离心力作用下砂轮架与砂轮振动的稳态响应幅值及其动力放大因子β1、β2的理论计算公式,着重分析砂轮离心力激振下砂轮架及砂轮的振动特性及规律,结果表明：β1、β2的大小和砂轮与砂轮架的质量之比µ、固有频率之比α,砂轮角频率与固有频率之比λ,阻尼比ξ等因素有关;合理选择µ、α、ξ值,可使砂轮与砂轮架具有相同且较小的动力放大因子;避免砂轮工作在λ=0.9~1.1对应的转速范围内,可有效减轻砂轮架及砂轮的振动程度。研究结果突破了现有研究将砂轮轴刚性化处理、试验测试装备复杂等缺陷,具有物理概念清晰、计算简单等特点。     

Effect of ball mill grinding parameters of hydrated lime fine grinding on consumed energy

The influence of several grinding parameters such as charged material volume, ball filling ratio, and mill rotation speed on energy efficiency of fine grinding of hydrated lime and the product fineness of hydrated lime was studied experimentally using a laboratory scale ball mill. The product size and surface area of the ground samples were determined with respect to the above variables, and changes in energy input during the grinding were described in detailed. Finally, the optimum conditions for the grinding of the hydrated lime with the ball mill were obtained. The results from this study showed that the ball mill load and mill speed are the most important parameters rather than ball mill charged material volume for the fine grinding of the hydrated lime using the ball mill in terms of energy efficiency associated with external surfaces.     

Effects of grinding aids on the grinding kinetics and surface morphological characterization of quartz

The kinetic parameters of a grinding process can be used to study the variations in particle size reductions and grinding efficiencies. Appropriate grinding aids usually change the surfaces of a material and the properties of the pulp, thus improving the grinding efficiency. In this paper, pure quartz samples with mixed particle sizes and single particle sizes were selected as the raw materials. The effects of different sodium tripolyphosphate (STPP) and citric acid (CA) dosages on the dynamic parameters k, selection function S₁ and breakage function B for quartz grinding were studied. The results showed that the STPP and CA enhanced the grinding process of the quartz. In other words, the parameter k, the selection function S₁ and the breakage function B were all increased to varying degrees. The results of SEM, BET and contact angle measurements showed that the surfaces of the quartz particles became rounder, the specific surface area and average pore size increased, and the surface hydrophilicity increased. As a result, the grindability of the quartz increased, and the grinding kinetic parameters changed. Finally, the results showed that the improvements in the quartz grindability were consistent with the influence of grinding aids on the kinetic parameter k, selection function S₁ and breakage function B_i,1.     

Impact of grinding aids on dry grinding performance,bulk properties and surface energy

In dry fine grinding processes the relevance of particle-particle interactions rises with increasing product fineness. These particle-particle interactions reduce the grinding efficiency and complicate the process control. The adsorption of grinding aid molecules on the product particle surface is a common measure to handle these effects. To ensure an efficient grinding aid application, the impacts of additives on particle and bulk properties, which influence the micro-processes inside the mill, need to be understood. Within this study the effects of several grinding aids on dry fine grinding of limestone in a laboratory vibration mill were investigated. Unlike in many other scientific works, the impacts of grinding aids were analyzed on different levels simultaneously: Grinding success and agglomerate size distributions were evaluated by wet and dry particle size measurements, respectively. Additionally, material coating on the grinding media, powder flowabilities and particle specific surface energies were measured. It was shown that all of the investigated grinding aids influence the grinding efficiency. However, the formation of agglomerates is not necessarily linked to the product fineness. Furthermore, a strong impact of certain grinding aids on the flowability of the product powder was determined. Thereby, the bulk flow behavior also determines the grinding result as it affects the stress mechanism inside the mill. Moreover, a direct relation between surface energy and powder flowability as well as agglomeration behavior could be demonstrated.     

轮胎辊与锥辊立磨粉磨过程力学分析

为了对立磨中轮胎型和锥型磨辊的粉磨过程进行分析比较,运用微分剪切理论建立轮胎型与锥型磨辊研磨物料的数学模型:通过建立磨辊-物料接触区域不同位置料层厚度的数学公式,得出料层微分单元受力的平衡方程;将方程积分得到磨辊与物料接触力及接触面积的大小。通过计算,得出在研磨过程不同参数(料层厚度、工作压力以及磨辊偏角)与接触面积之间的关系,并对2种磨辊进行比较分析。结果表明:磨辊偏转角度越大,磨辊所受应力峰值越大;在相同工作条件下,轮胎辊与物料有更大的接触面积,较小的应力峰值。     

Lifetime increase method of cutting ability of grinding wheels in the process of magnesium alloy grinding

Im Artikel wurde ein neues Verfahren zum Schleifen von Magnesiumlegierungen mit Hilfe von keramischen Schleifscheiben dargestellt. Bei dieser Methode wurde ein neues Verfahren zur Konditionierung der aktiven Oberfläche der Schleifscheibe (Reinigung) angewendet. Es zeigte sich, dass dieses Verfahren die Schnittkapazität von Schleifscheiben um ein Vielfaches erhöht. Zusätzlich wurde die geometrische Struktur der Oberfläche nach dem Schleifen im 3D‐System bewertet und die darauf erzeugte diamantähnliche Schicht dargestellt.     

Experimental investigations into electric discharge grinding and ultrasonic vibration-assisted electric discharge grinding of Inconel 601

The paper presents experimental investigations into electric discharge grinding (EDG) and ultrasonic vibration-assisted electric discharge grinding (UVAEDG) of Inconel 601. The process parameters selected for both processes were duty cycle, discharge current, pulse on time, grinding wheel speed, work speed, and speed ratio to study their influence on responses like surface roughness (R_a) and material removal rate (MRR). It was found that duty cycle, wheel speed, work speed, discharge current, speed ratio, and pulse duration significantly influenced MRR and R_a. It was inferred that MRR increased with increase in duty cycle, wheel speed, current, work speed, and pulse duration in both EDG and UVAEDG processes. It was also inferred that R_a increased with rise in duty factor, pulse on time, and discharge current in EDG and UVAEDG processes.