Characteristics of common universal material testing machine
1 , conventional electronic universal material testing machine
Â Â Â Â Â This type of testing machine is the mainstream product of today's universal material testing machine. It uses servo motor as the power source, screw and nut as the actuator, and realizes the speed control of the moving beam of the testing machine. It is easy to operate and does not require the tester. High, the test stroke can be arbitrarily customized as needed. Although the control method is relatively simple, only the speed is a control method, but its control precision and control range are very wide and wide. Taking Shanghai Xieqiang Instrument Co., Ltd. as an example, its speed adjustment range can reach 0.001mm / min ~ 1000mm / min , stepless speed regulation, control accuracy can reach 0.5% , small tonnage models are easy to implement. When the coefficient of friction is used, the full load is only 5N . It has great configuration flexibility, and can be equipped with different tonnage sensors, fixtures and accessories to achieve multi-purpose, complete the functions of pulling, pressing, bending, shearing, peeling, tearing, friction coefficient and torsion. Throughout the relevant standards for the testing of mechanical properties of plastics, almost all the requirements for the control mode of the testing machine are speed control. Therefore, no matter from the control mode or the speed range, the test stroke and the tonnage of the testing machine, this type of machine is plastic mechanics. The first choice for performance testing.
2 , three closed-loop electronic universal material testing machine
Â Â Â This type of testing machine has the advantages of wide speed range, large test stroke and flexible configuration, and the advantages of electro-hydraulic servo test force, displacement and deformation control. Therefore, it is a kind of testing machine with better performance, but the stability of the machine is closely related to the rigidity of the main machine and the rigidity of the sample due to the force control and deformation control. General plastics tester small tonnage host so low rigidity, and the rigidity of the sample itself is not too large, so there is little such testing machine 10KN the following models, the following models is 10KN plastic most commonly used. It is said that the stability of this type of machine is related to the sample. If the sample is single, the test method is also single, and it can be used. Otherwise, the control parameters of the test machine need to be adjusted at any time (that is, the conventional P , I , D Parameter), which is almost unimaginable for non-automatic control professionals. Therefore, from the overall point of view, in addition to the specific requirements of the control method, it is not easy to choose the test of plastic materials.
3 , simple electric pull
Â Â Since the tensile strength of plastic is a very important indicator for testing the mechanical properties of plastics, in the past few years, there were not many types of plastics, and the application was not very wide. The mechanical properties of plastics were still relatively simple, and the corresponding standards were also Not very perfect. In this period, a structure is very simple, the use is very simple, and the performance index is very lacking, but the single-purpose tensile test machine with a motor as a power source is commonly used as a power source. As the name suggests, it can only be used for a single tensile test, and the data that can be processed is very limited, and the control measurement accuracy is relatively low. Now, although it is still used in some occasions, it has gradually become a single function. Eliminated for the market.
4 , electro-hydraulic servo universal material testing machine
Â Â Â Â This kind of testing machine is a kind of testing machine with better performance at present. Because it adopts electro-hydraulic servo control technology, it can realize closed-loop control of force, displacement and deformation, and has good control performance. At present, metal, building materials and the like require constant stress, constant strain and need to carry out creep test. However, due to the limitation of the flow rate of the oil source, his test speed is low. In order to increase the rigidity of the system and ensure the stable operation of the closed-loop control, the stroke of the test machine is small, and the operation is complicated, and the expansion configuration is difficult. There are few models below 10KN , so it is not suitable for the test of plastic rubber materials.
5 , manual hydraulic universal material testing machine
Â Â Â Â This type of testing machine is the "first ancestor " of the testing machine family. It has a long history, is simple to use, low in price and large in tonnage. As the name implies, manual hydraulics indicate that it is open-loop control, performance is poor, and the operation process is completely dependent on the operator's operating level. In addition, due to its mechanical structure and hydraulic loading principle determines its loading speed, the test stroke is small. At present, the minimum model of this type of testing machine is 50KN , so its small load measurement accuracy is very low, and the expansion configuration capability is very poor. It is generally used only for structural component testing or simple material performance testing, such as the unplugging of connecting parts. , the tensile strength of steel bars and other occasions.