新型移动式热湿拉强度测试仪研制

Development of New Movable Hot-wet Tensile Strength Tester

热湿拉强度是表征型砂力学性能的重要指标之一,在传统的热湿拉强度设备研究中,设计者多数将测试仪定位在实验室检测或现场的检测,使其无法兼顾实验室和生产现场的检测;同时,传统的测试仪多数存在无法实时观察型砂热湿拉强度曲线动态变化的问题,而只能获得到一个强度值,这就使得试验者无法准确掌控整个测试过程。为此,设计一款新型移动式热湿拉强度测试仪,既可满足实验室检测又能适应生产现场检测,还能实时观察热湿拉强度曲线动态变化,具有一定意义。测试仪以GB/T2684—2009《铸造用砂及混料试验方法》为基准,以型砂微变形理论为设计基础,通过计算机、PLC、高精步进电机、传感器、采集器等完成硬件的设计,以DELPHI为编程语言完成测试界面及软件设计,稳定的实现了对标准试样测试过程中的数据实时采集、处理及保存等功能,并实时绘制热湿拉强度-时间-温度曲线。整体结构采用框架式,在保障结构稳定性的同时极大程度减轻整体重量,且测试仪底部配有万向轮便于测试人员移动。最后,用自主研制的新型移动式热湿拉强度测试仪与某品牌测试仪进行了对比试验,采用标准方法进行制样,试验结果表明,本测试仪具有较高的精确度和精密度,且操作更加方便。

Hot-wet tensile strength is one of the important indexes to characterize the mechanical properties of molding sand.In the study of traditional hot-wet tensile strength equipment,most designers design the tester to only be used for laboratory or on the spot,so make it impossible to test both in laboratory and the production site.At the same time,most of the traditional testers cannot observe the dynamic change of the hot-wet tensile strength curve in real time,but can only obtain one strength value,which makes the tester unable to accurately control the whole testing process.Therefore,it is significant to design a new type of mobile hot-wet tensile strength tester,which can not only meet the needs of laboratory testing,but also meet the needs of production site testing,and can observe the dynamic changes of hot-wet tensile strength curve in real time.The tester is designed on the basis of GB/T 2684—2009 Test Methods for Foundry Sands and Molding Mixtures and the theory of molding sand micro deformation.The hardware is designed by PC,PLC,high precision stepping motor,sensor and collector,and the software is designed by DELPHI programming language.The tester can stably realize the functions of real-time data collection,processing and storage in the process of testing standard samples,and draw the curves of hot-wet tensile strength and temperature with time in real time.The overall structure adopts frame type,which can greatly reduce the overall weight while ensuring the stability of the structure,and the bottom of the tester is equipped with universal wheels to facilitate the movement of the tester.Finally,the new type of self-developed mobile hot-wet tensile strength tester is compared with a brand of tester,and the standard method is used for sample preparation.The test results show that the tester has high accuracy and precision,and the operation is more convenient.