共查询到13条相似文献,搜索用时 0 毫秒
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AbstractThis investigation presented a quantitative evaluation technique of the hole entrance chippings with respect to the image processing technology. Considering the nucleation and propagation processes of lateral cracks, the chipping formation mechanisms involved in rotary ultrasonic drilling of glass BK7 were also explored incorporated with the abrasive kinematics and the fracture mechanics of brittle material. As a result, it was revealed that each individual chipping represented a smooth appearance at the chipping inside, and the instantaneous nature of the lateral crack formation process was responsible for this damage feature. Moreover, the friction effects between the abrasive and the material caused the lateral crack suffering from the extra torsional moment, resulting in the scattered fracture stripes on the chipping outside. A novel evaluation method of hole entrance quality, founded on the pixel rate of the chipping area to hole perimeter, was proposed, which could provide a more accurate measurement by considering the comprehensive effects of all chippings on the entrance quality. The increased rotation speed of the tool prolonged the plastic deformation region in the interior material along the abrasive scratching direction, severely deteriorating the entrance quality of the drilled hole. 相似文献
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Edge-chipping, surface roughness and dimensional accuracy are crucial quality aspects of drilled holes in hard-to-cut material such as glass, ceramics and carbon fiber reinforced plastics. In this article, an experimental study was conducted to investigate the quality measures of holes produced by rotary ultrasonic drilling (RUD) and conventional drilling. Edge-chipping width at tool exit side, the surface roughness (Ra and Rz), out-of-roundness, cylindricity error and hole conicity were the main responses when drilling soda glass using diamond abrasive tools and a cutting fluid. Statistically designed experiments were carried out for rotary ultrasonic and conventional drilling (CD) at two levels of tool feed rate (0.6 and 6?mm/min), spindle speed (3,000 and 8,000?rpm) and tool particles-concentration. Analysis of variance was used to define the significant factors and their interactions and build models for predicting the responses. The results showed that reducing the chipping, surface roughness and roundness error. The normal tool concentration showed a substantial effect in improving the surface quality and reducing the hole-geometrical errors. 相似文献
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AbstractThe carbon fiber reinforced plastic (CFRP) has been widely used in manufacturing industry due to its excellent mechanical and physical properties. Brad drill, as a representative of new-type structural drills, is applied in processing of CFRP. Meantime, rotary ultrasonic drilling (RUD) is regarded as a superior method for machining composite materials, due to its outstanding performance in lowering thrust force and improving processing quality. However, there are few reports about RUD with Brad drill in CFRP drilling. In this study, the theoretical model of thrust force for RUD of CFRP using Brad drill is developed. The dynamic uncut chip thickness and average uncut chip thickness in RUD are obtained based on kinematic characteristics analysis. After that, the structure of Brad drill is analyzed and thrust force of the cutting lip is molded. Then a theoretical model is proposed to predict the thrust force. Finally, pilot experiments are conducted for the model verification. Experimental results show that the trends of thrust force agree well with the thrust force model and the prediction error is less than 10%. 相似文献
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实验分析了硬脆材料旋转超声磨削过程中刀具结合剂类型对加工性能的影响以便提高加工精度和加工表面的完整性.首先,采用能谱分析研究了铁基、陶瓷基和青铜基3种超声振动刀具中结合剂与金刚石颗粒的把持形式,并根据相同加工工艺条件下刀具磨损形式确定了把持力大小.然后,结合超声振动刀具特性,通过旋转超声磨削加工实验研究刀具结合剂类型与切削力、刀具磨损量、加工表面完整性的关系,并对实验结果进行了分析.实验结果表明:相对于陶瓷基和青铜基结合剂超声振动刀具,铁基结合剂超声振动刀具把持力最大,Z轴切削力平均值最小(为46.8 N);加工18 000 mm3材料后,刀具轴向磨损量最小(为0.1 mm);而陶瓷基结合剂超声振动刀具加工表面质量最好,表面粗糙度最大值为21.79 μm.结果证实铁基超声振动刀具适用于粗加工,陶瓷基超声振动刀具则适用于精加工. 相似文献
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M. Adithan 《Tribology International》1988,21(3)
The hardening mechanism of tools in ultrasonic drilling was investigated by studying the variation in the microhardness of the tools used and the X-ray diffraction patterns obtained. Various tool and work material combinations were used, and the extent of increase in microhardness of tool materials was analysed. In addition, the nature and extent of the residual stresses left on the surfaces of the tools used were investigated. 相似文献
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Ultrasonic vibration is assumed to be stable or unchangeable during the process of rotary ultrasonic machining (RUM) on brittle materials, neglecting the effects of different processing parameters. However, no experimental evidence has been reported to validate this assumption. In this study, the effect of thermomechanical load on the stability of ultrasonic amplitude during RUM was investigated by theoretical analysis and experimental procedures on quartz glass and sapphire. It was shown that the instability of ultrasonic amplitude during the machining process is mainly attributed to variation of resonant frequency under the implementation of thermomechanical load. The thermal effects of ultrasonic vibration decrease the resonant frequency of the ultrasonic machine, while mechanical loading during the machining process increases the resonant frequency. Furthermore, a higher feed rate or a harder material leads to a higher resonant frequency change. The variation of ultrasonic power can be used to review the validity of difference-neglected assumption when different values of processing variables, materials, or even machine tools are used during modeling. The results of this study should be well considered for future references when designing an ultrasonic machine. 相似文献
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Wenyuan LI Yu HUANG Youmin RONG Long CHEN Guojun ZHANG Zhangrui GAO 《Frontiers of Mechanical Engineering》2021,16(1):97-110
Cutting quality and efficiency have always been important indicators of glass laser cutting. Laser scanning modes have two kinds, namely, the spiral and concentric circle scanning modes. These modes can achieve high-performance hole cutting of thick solar float glass using a 532-nm nanosecond laser. The mechanism of the glass laser cutting under these two different scanning modes has been described. Several experiments are conducted to explore the effect of machining parameters on cutting efficiency and quality under these two scanning modes. Results indicate that compared with the spiral scanning mode, the minimum area of edge chipping (218340 µm2) and the minimum Ra (3.01 µm) in the concentric circle scanning mode are reduced by 9.4% and 16.4% respectively. Moreover, the best cutting efficiency scanning mode is 14.2% faster than that in the spiral scanning mode. The best parameter combination for the concentric circle scanning mode is as follows: Scanning speed: 2200 mm/s, number of inner circles: 6, and circle spacing: 0.05 mm. This parameter combination reduces the chipping area and sidewall surface roughness by 8.8% and 9.6% respectively at the same cutting efficiency compared with the best spiral processing parameters. The range of glass processing that can be achieved in the concentric circle scanning mode is wider than that in the spiral counterpart. The analyses of surface topography, white spots, microstructures, and sidewall surface element composition are also performed. The study concluded that the concentric circle scanning mode shows evident advantages in the performance of solar float glass hole cutting. 相似文献
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为研究旋转超声电解复合加工小孔的成型过程,进行了旋转超声电解复合加工小孔试验,得到了不同加工时间孔的截面,并根据试验参数,进行了基于ANSYS的二维仿真加工和三维仿真加工。对小孔的入口直径、底面直径和加工深度进行了对比分析,结果表明由于三维仿真加工中采用了管电极,并考虑了电解加工中阴极超声高频振动对电解液电导率的影响,故其仿真结果更加接近试验值,间接证明了旋转超声电解复合加工小孔三维仿真加工的可靠性,展示了不同时刻的三维加工型腔,为旋转超声电解复合加工的成型过程和成型规律的研究提供了参考。 相似文献
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Tailored surface textures at the micro- or nanoscale dimensions are widely used to get required functional performances. Rotary ultrasonic texturing (RUT) technique has been proved to be capable of fabricating periodic micro- and nanostructures. In the present study, diamond tools with geometrically defined cutting edges were designed for fabricating different types of tailored surface textures using the RUT method. Surface generation mechanisms and machinable structures of the RUT process are analyzed and simulated with a 3D-CAD program. Textured surfaces generated by using a triangular pyramid cutting tip are constructed. Different textural patterns from several micrometers to several tens of micrometers with few burrs were successfully fabricated, which proved that tools with a proper two-rake-face design are capable of removing cutting chips efficiently along a sinusoidal cutting locus in the RUT process. Technical applications of the textured surfaces are also discussed. Wetting properties of textured aluminum surfaces were evaluated by combining the test of surface roughness features. The results show that the real surface area of the textured aluminum surfaces almost doubled by comparing with that of a flat surface, and anisotropic wetting properties were obtained due to the obvious directional textural features. 相似文献
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AbstractAn aluminum-based printed circuit board (Al-PCB) is a composite material comprising a copper layer, an insulating layer, and an aluminum base layer. In the drilling of Al-PCBs, exit burrs are formed because of the plastic deformation of the remnant aluminum under high drilling temperatures. In this work, a new method using cryogenic media is suggested to prevent exit burrs in Al-PCB drilling. The effects of cryogenic media, such as cold air, supercritical carbon dioxide solvent (scCO2), and liquid nitrogen (LN2), on the drilling temperature, chip removal, tool wear and exit burr formation were observed and analyzed. The Al-PCB drilling temperature could be effectively reduced when drilling with cold air, scCO2 or LN2. The chip removal and tool wear could be improved when drilling with cold air or LN2. The exit burr formation when drilling with scCO2 or LN2 was greater than that when drilling under cooling and cold air conditions. A cold air matching composite wood backup board (MW-0.5) could effectively control the exit burr formation within 20?μm. This is the first study on the effects of three different cryogenic media on PCB drilling and is expected to provide a good reference for the cryogenic drilling of PCBs. 相似文献