共查询到19条相似文献,搜索用时 171 毫秒
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力值计量标准现状及研究进展 总被引:1,自引:0,他引:1
在对比分析国际上各类力标准机计量性能的基础上,阐述了我国力值计量标准的研究现状及应用关键技术的先进性.提出并研制了基于静重式力标准机"独立加码"的技术与方法,解决了力标准机砝码逆程交换带来的负荷波动性过大的问题,为进一步研究砝码逆程交换产生的"逆负荷现象"提供了一种有效的技术方法.提出并研制了利用机械传动加载方式的叠加式力标准机,力传感器分组并联延伸力值的试验方法,以及力标准机参考标准量值溯源的方法,对研究建立新的大力值计量标准,具有参考和借鉴意义. 相似文献
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静重式力标准机砝码交换力平衡控制技术 总被引:1,自引:0,他引:1
静重式力标准机利用少量的砝码,进行相等力值间隔逐级加、卸荷时,需要交换砝码。当砝码进行交换时出现逆负荷现象,会对被检测力仪的示值产生影响。阐述了静重式力标准机采用的交换砝码方法是建立在利用弹性力替代砝码重力,砝码交换过程中重力与弹性力达到平衡的基本原理。提出了实现静重式力标准机砝码交换时系统达到力平衡的一种预加荷装置,经砝码交换力平衡控制的力学分析与实验验证,静重式力标准机采用预加负荷实施倒码力平衡控制的方法在理论上和技术上是可行的、有效的。 相似文献
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叠加式力标准机作为力值计量标准器,广泛应用于各行业。叠加式力标准机采用标准传感器与被测传感器比对的方法实现力值的加载控制,通过对力值施加过程及压电陶瓷力发生装置的逆压电效应工作原理分析,结合计算机和微电子控制技术,设计力标准机专用控制软件实现其自动加载控制、数据采集、数据处理、报表输出等功能;并对力标准机进行数据测试及功能测试,测试结果满足国家检定规程要求。 相似文献
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力标准机是力学计量中对各种力传感器、测力仪和称重传感器进行检定或测试的设备,它通常分为静重式、杠杆式、液压式、叠加式等类型。力值不确定度主要取决于砝码质量的不确定度、安装地点重力加速度的测量不确定度、砝码和空气密度的测量不确定度,同时还与砝码的稳定性、加卸方式及机器的结构有关。本文提出了一种杠杆式力标准机电气控制系统的设计方案, 相似文献
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本文介绍一种大力值,易控制,高精度,宽频带的负阶跃力发生装置。该方法是利用帕斯卡原理,由小油缸上的标准砝码在大油缸上产生一个放大的力值,然后利用冲击加卸油的方式撤消该力值以产生该负阶跃力。 相似文献
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John Jones (pseudonym), injection engineer for Corporation X, gave our student project group from Iowa State University the challenge of determining the most influential variables affecting weights of preform plastic beverage bottle produced by injection-molding machines. In addition to determining which variables are most important, we were charged with identifying settings for the variables that will produce optimal preform weights. We benchmarked the current injection-molding process to get an idea to typical performance. This allowed us to compare later experimental results to typical process output.
From company experience with the process, the team and Mr. Jones identified injection time, injection pressure, hold time, and hold pressure as candidates for the variables most influential on preform weight. The team devised a matrix of experimental conditions to study that consisted of combinations of high, low, and medium values of these process variables. After experimentation with the injection-molding process, regression analysis was used to help determine which factors are most influential in determining preform weight. The group determined that hold time and hold pressure are the two most influential factors in determining mean preform weight. The group also determined that hold pressure has the primary influence on the consistency of preform weight across the cavities in the mold. Using regression equations for mean weight and a within-die standard deviation, new machine settings for hold time and hold pressure were recommended. Additional runs were then performed to validate our recommendations. Ten runs were made with hold pressure set to 1140 psi and hold time set to 3.95 s. The average weight of 50 preforms from the verification experiment was 23.41 g with a standard deviation of 07 g. These results compare well to the engineering specifications of 23.9-22.9 g set on preform weights. A subsequent comparison of routine process monitoring data collected after implementing our recommendations with historical process data also confirms the substantial improvement provided by our analysis. 相似文献
From company experience with the process, the team and Mr. Jones identified injection time, injection pressure, hold time, and hold pressure as candidates for the variables most influential on preform weight. The team devised a matrix of experimental conditions to study that consisted of combinations of high, low, and medium values of these process variables. After experimentation with the injection-molding process, regression analysis was used to help determine which factors are most influential in determining preform weight. The group determined that hold time and hold pressure are the two most influential factors in determining mean preform weight. The group also determined that hold pressure has the primary influence on the consistency of preform weight across the cavities in the mold. Using regression equations for mean weight and a within-die standard deviation, new machine settings for hold time and hold pressure were recommended. Additional runs were then performed to validate our recommendations. Ten runs were made with hold pressure set to 1140 psi and hold time set to 3.95 s. The average weight of 50 preforms from the verification experiment was 23.41 g with a standard deviation of 07 g. These results compare well to the engineering specifications of 23.9-22.9 g set on preform weights. A subsequent comparison of routine process monitoring data collected after implementing our recommendations with historical process data also confirms the substantial improvement provided by our analysis. 相似文献
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在电液负载模拟器进行动态力加载时,对其快速性指标有更高要求,此时加载误差比较大的问题就凸显出来,即输出加载力的数值随加载频率的增大而增大、相位也有超前,针对加载系统的这一性能特殊变化规律与实际现象,提出基于最小均方算法的自适应神经网络控制策略。该方法对神经网络的配置权值进行实时在线调整,调整效率和算法的收敛性都有明显提高,可以有效减小控制系统工作时的循环调整时间。当输入信号经过加权运算后作用于加载控制系统时,加载误差明显减小,加载系统的快速性与跟踪精度进一步提高。仿真和实验结果表明,采用文中方法后,加载力输出的幅值增大和相位超前量得以抑制,系统动态力加载时的综合性能有所提高,所提出算法调整规则有效。 相似文献
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负荷传感器试验的准静态加荷方法研究 总被引:1,自引:0,他引:1
通过对叠置加荷方式工作过程的分析,讨论了非静态加荷问题。由于传感器和仪表的静态性能与动态性能的差异、动态性能的离散性,以及测量过程中采样频率、采样间隔和数据处理等因素均会对试验的力值计量精度产生影响,因此采用非静态加荷方式进行负荷传感器负荷特性试验会产生测量误差。理论分析证明,采用非静态加荷方法提高试验工作效率、保证测量精度的关键在于加荷速度的控制和正确的采样与数据处理方法。本文提出了准静态加荷这一概念,并对准静态加荷方法的实现及其在负荷传感器试验中实施的可行性进行了理论和试验研究。结果表明,受技术条件的限制,动态加荷是不现实的,而准静态加荷确是可行的非静态加荷方法。它满足负荷传感器负荷特性试验中试验工作效率高、保证测量精度、容易实施和生产成本低的要求。 相似文献
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提出了一种变臂比双杠杆原理的加载方法,该方法安放试件后无需配平,加载系统由主、辅两套杠杆系统组成,主杠杆利用变臂比原理施加载荷,而由辅助杠杆实现杠杆系统的初始平衡。将系统对力的大小和加载速度控制转变为位移的精密控制,可获得较宽的力值范围、较小的力值误差和高的加载工作效率。阐述了这种方法的基本原理,并做了误差分析。对所研制的1MN变臂比双杠杆式力标准机进行了检验,给出了试验数据和检验结果。力值准确度可以达到0.01%。 相似文献
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介绍了大力值标准测力机中使用的一种新型静压润滑原理的工作缸塞系统。由于油缸不转动,其有效长度得以减少,从而使工作油缸和活塞的超精加工成为现实。这种带有高压密封和零压槽的缸塞结构,还有助于消除工作油压控制的波动而造成的力值波动,从而可以改善液压式标准测力机的计量性能。实验表明,使用静压缸塞系统的20MN基准测力机,其力值不确定度优于0.01%,而灵敏阀优于0.001%。 相似文献
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介绍了中国计量科学研究院新研制的基于空气轴承支撑技术的1mN·m~1N·m微小扭矩标准装置的工作原理、机械结构、性能试验和不确定度评定。该装置采用静压空气轴承作为力臂杠杆的支撑部件;力臂杠杆系统采用单臂结构,并配备了配平机构和力臂限位保护机构;砝码加载机构采用砝码吊挂、砝码组和砝码支撑系统精密结合的方式。理论分析和性能试验表明:该装置的相对扩展不确定度(k=2)在1~5mN·m范围内小于3.4×10-4;在5~100mN·m范围内小于7.4×10-5;在100mN·m~1N·m范围小于2.6×10-5。 相似文献