Surface-layer quality in shot treatment

The quality of the surface layer in shot treatment is considered. An individual interaction of a ball with the surface of the treated part is investigated. Formulas are presented for the mean deviation of the roughness profile, the depth of the hardened layer, and the degree of hardening. These formulas are verified experimentally and may be used in the design of shot-treatment processes, to predict the roughness and the depth and degree of hardening of the treated surface.     

弹丸初速的测定方法

弹丸的初速度，是指炮弹离开炮口时的速度，是检查火炮性能的一项重要技术指标。本文介绍电子测时仪的组成和工作原理，以及弹丸的初速度是如何测定的。     

Temperature in contact zone during shot hardening

Shot hardening is simulated by the single impact of a rigid spherical particle on a flat steel surface (an elastic halfspace). The corresponding results of thermophysical analysis are presented. Formulas are derived for the temperature at any point in the impact zone and the time for the shot to reach a minimal depth in hardening.     

Influence of target hardness on impact damage of shot

A comparative study of the degradation of S-460 shot due to target hardness was carried out by impacting the shot against white and gray cast iron targets in a laboratory testing machine and against a gray cast iron hydrant in a WTB6 production blasting machine. The hardness of the white cast iron target was 65 HRC while that of the gray cast iron targets was 22 HRC.

A total of 500 impacts (cycles) were run during the three experiments and samples for metallurgical investigation were taken after every 50 impacts.

Shot damage was analyzed by measuring the shot fragmentation and stereology and the chemical degradation of the shot. Characteristic failure mechanisms are found for shot impacted against soft and hard targets. Evidence indicates that the present laboratory shot-life-testing machine for peening and/or cleaning applications with a hard target cannot reproduce the breakdown characteristics of shot impacted against a soft target. A new laboratory testing machine is proposed.     

Assessing the surface roughness of parts after shot hardening

A formula for the surface roughness Rz in the shot hardening of machine parts is derived on the basis of energy relations. Its dependence on the physicomechanical properties of the materials and the geometric and kinematic parameters of the shot is established.     

高强度钢喷丸强化处理的试验研究

喷丸强化是一种以小而硬的弹丸连续高速撞击金属零件表面而进行的一种特殊加工方法,零件通过喷丸可以大大提高材料的疲劳性能和抵抗应力腐蚀的能力。针对某型飞机上的喷丸强化零件,选取材料牌号为16Co14Ni10Cr2Mo高强度钢为研究对象,对两种厚度的试样进行不同喷丸强度的喷丸强化,对不同喷丸强度的试样进行疲劳寿命和残余应力场对比分析。     

超声喷丸中级联式变幅杆的动力学特性研究

超声强化能有效地提高工件的疲劳极限,延长其疲劳寿命.丸粒速度是影响超声喷丸强化效果的重要因素,而变幅杆振幅的提高可以显著地提高丸粒速度.以提高变幅杆振幅为目的,用解析法设计了级联式变幅杆;在此基础上,用ANSYS软件对其进行了动力学分析,得到了比单一变幅杆更大的振幅放大比.     

全局注意力关系网络的小样本船舶识别

实际场景中采集的船舶目标类别样本数量不均衡,模型训练易导致过拟合。 传统迁移学习的数据集划分存在类别交 叉,造成未标注新类别识别精度低。 为解决上述问题,提出了一种跨目标通用全局注意力机制与关系度量网络融合的小样本船 舶识别算法。 该方法通过在关系网络中引入全局注意力机制,利用关系网络提取到的原始特征,经过全局注意力机制平滑不均 衡类别间的目标特征,并与关系网络提取的原始特征融合后进行特征距离度量。 该方法增强了全局特征之间的一致性,有利于 学习不变的目标特征,提升少样本少标签的船舶目标识别性能,解决了训练过程中类别不均衡导致的过拟合问题。 利用自己采 集制作的船舶数据集对本文方法进行测试实验,识别精度提高了 5. 6% (5-shot)、3. 2% (1-shot),减小了不均衡类别对模型目标 识别造成的影响,增强了模型的鲁棒性。     

结合多特征的视频镜头检测方法

针对视频镜头边缘检测准确率低的问题,提出了一种新的基于多特征的视频镜头检测算法。首先按时序读取多帧图像,并转换为灰度图;进一步将帧图像均匀分块,计算每个图像块的平均梯度,构造视频动态纹理;比较相邻帧视频动态纹理的相关性及两帧SIFT特征的匹配程度,根据匹配结果得出预检测结果;接下来与步长低于人眼刷新频率的下一帧动态纹理及SIFT特征相比较,得到最终的结果。通过对多组不同类型的视频数据进行实验,均能取得较高的召回率和准确率。该文算法对结构较复杂的渐变镜头进行检测,也能取得较高的检测准确率和召回率。     

基于ANSYS/LS-DYNA的受控喷丸工艺过程仿真

将喷丸过程简化为丸粒撞击工件的模型,丸粒看作刚性体,运用ANSYS/LS-DYNA软件进行了数值模拟,分析了覆盖率对残余压应力分布的影响,得出在不完整喷丸覆盖率下工件表面会产生残余拉应力.在单个丸粒模型中,将丸粒的材料改为塑性硬化材料,分析丸粒的速度对残余压应力分布的影响,得出丸粒的材料参数一定时,存在最优喷丸速度,丸速过高会导致丸粒的变形能增加,而使工件表层的最大压应力值和应力层深度下降.     

抛丸器常见故障的排除

介绍抛丸器的常见故障及发生原因,并对抛丸器的安装、使用及维护提出建议。     

Kinematic modeling and deformation mechanics in shot peening of functional ceramics

The applications of functional ceramics are significantly limited by the brittleness and low reliability. Recent studies have shown that compressive residual stress can be created in ceramics by shot peening, which improves the contact strength and fatigue of ceramic components. However, the formation mechanism of residuals stress in shot peening is yet to understand. In this study, a pressure-dependent plasticity model has been incorporated into a finite element simulation model of shot peening to understand the process mechanism underpinning the residual stress formation. Since shot velocity is the key process parameter to dominate the impact energy which determines the deformation state of the peened surface and the resultant residual stress, a new kinematic model of shots has also been developed by incorporating air drag and travel distance inside and outside the peening nozzle. The results have shown that the shot velocity model can be used to predict shot velocity. The experiment-based model may help understand the process mechanism underpinning the residual stress formation.     

Surface durability of powder-forged roller treated by shot peening

To investigate the influence of shot peening on the surface durability of powder-forged rollers, the case-hardened powder-forged rollers with a forging density of 7.5 g/cm³ treated by the single shot peening and the double shot peening were fatigue-tested under a sliding-rolling contact condition. The surface roughness, the surface hardness and the surface compressive residual stress of the rollers were increased by the shot peening. In addition, the pores near the roller surface were deformed by the shot peening. The failure mode of all the test rollers was spalling due to subsurface cracking. The fatigue lives of all the test rollers were improved by the shot peening, and that of the test roller S08, which was shot-peened with the hardest steel shots in this experimental range, was especially improved. The surface durability of the test roller S08 was also most improved by the shot peening. Cracks became difficult to occur and propagate under the roller surface since the pores near the roller surface were deformed by the stronger shot peening. In this study, double shot peening, which generally restrains the increase in surface roughness, was not particularly effective for the improvement in the surface durability of the powder-forged rollers, because the influence of tangential force on fatigue was not always great in a case of subsurface cracking.     

基于SolidWorks的抛丸清理机仿真系统设计

由于目前一般的仿真软件无法实现对抛丸清理机工况分析以及对抛射区域检查，本文介绍了如何运用SolidWorks建立产品模型，以及运用SolidWorksAPI和VB进行开发，实现抛丸清理机工作过程的运动仿真，同时实现对抛丸清理机工况的分析和抛射区域的检查，体现了产品的优越性。     

基于故障树的真空树脂灌注机可靠性分析

利用FTA方法对真空树脂灌注机的各种故障进行了系统的研究,建立了真空树脂灌注机的故障树,并对故障树进行了定性分析和定量分析,确定出具有针对性的改进措施,从而使真空树脂灌注机的可靠性指标有了大幅度的提高。     

Relation between surface hardening and roughness induced by ultrasonic shot peening

This paper is focused on the identification of a relation between surface hardening and roughness induced by ultrasonic shot peening. A method that dissociates the influence of roughness from the value of the true macroscopic hardness is applied to AISI 316L stainless steel specimens treated using different processing conditions. The true macroscopic hardness is identified and used to determine the surface roughness parameter and scale that give the best relation between hardness and roughness. A relation is identified between the five point pit height S_5V roughness parameter (local depth of roughness) and hardness using a high-pass filter with a cut-off of 100 µm. This power function was identified at a scale that corresponds to the size of the shot impacts.     

Effect of shot noise and secondary emission noise in scanning electron microscope images

The effect of shot noise and emission noise due to materials that have different emission properties was simulated. Local variations in emission properties affect the overall signal‐to‐noise ratio (SNR) value of the scanning electron microscope image. In the case in which emission noise is assumed to be absent, the image SNRs for silicon and gold on a black background are identical. This is because only shot noise in the primary beam affects the SNRs, irrespective of the assumed noiseless secondary electron emission or backscattered electron emission processes. The addition of secondary emission noise degrades the SNR. Materials with higher secondary electron yield and backscattering electron yield give rise to higher SNR. For images formed from two types of material, the contrast of the image is lower. The reduction in image signal reduces the overall image SNR. As expected, large differences in δ or η give rise to higher SNR images.     

Energy saturation of metal parts in surface plastic deformation (shot peening)

A new algorithm simulating the change in surface plastic deformation during shot peening is described. Using this algorithm, metallic panels with specified curvature may be produced.     

移动式抛丸机研究现状及关键技术分析

首先,简要介绍了移动式抛丸机的系统组成、工作原理以及在船舶、桥梁等领域的应用需求。然后,对国内外相关产品和研究成果进行了详细综述和对比分析,总结了我国与国外先进移动式抛丸机生产制造厂家的差距。最后,围绕移动式抛丸机集成及设计、关键部件设计与优化、抛丸过程演变及弹丸动力学,以及移动式抛丸工艺参数规划等关键技术进行了总结,并对移动式抛丸机的发展趋势进行了预测与展望。