Analysis of Mechanical Testing Machines and Selection Methods Introduction With the rapid advancement of science and technology, various new materials emerge in an endless stream, especially in recent years, with the rapid development of polymer materials. As a branch of polymer materials, plastics have made remarkable improvements in various properties. In some fields, there has been a trend to replace wood and metal materials. For the safe and reliable use of plastic materials and their products, it is very necessary to perform performance inspections, among which the mechanical properties test is one of the most important tests.
Here are some kinds of testing machines for reference:
1, conventional electronic universal material testing machine 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, nut as the actuator, to achieve the test machine moving beam speed control, it operates Simple, the tester's requirements are not high, the test trip can be customized according to need, although the control mode is relatively single, only a speed control method, but its control accuracy and control range is very high. Take Regel's testing machine as an example, the speed adjustment range can reach 0.001mm/min ~ 1000mm/min, stepless speed regulation, control accuracy can reach 0.5, small tonnage model is easy to achieve. For friction coefficient, the full load is only 5N. It has a great deal of configuration flexibility, can be equipped with different tonnage sensors, fixtures, accessories to achieve a multi-purpose, to complete the pull, pressure, bending, shearing, peeling, tearing, friction coefficient, twisting and other functions. Throughout the relevant standards for the inspection of the mechanical properties of plastics, almost all the requirements for the control methods of the testing machine are speed control. Therefore, regardless of the control method or the speed range, the test stroke and the tonnage of the testing machine, these models are all plastic mechanics. The first choice for performance testing.
2, three closed-loop electronic universal material testing machine This type of testing machine has a wide range of conventional electronic universal testing machine speed, large test stroke, flexible configuration features, but also has the advantages of electro-hydraulic servo testing machine force, displacement, deformation control . Therefore, it is a kind of testing machine with better performance, but due to the force control and deformation control, the stability of the machine is closely related to the rigidity of the host and the rigidity of the sample. The tonnage of general plastic testing machine is small, so the rigidity of the main machine is low, and the rigidity of the sample itself is not too large. Therefore, these testing machines rarely have the following 10KN models, while the following 10KN models are plastics. most commonly used. As mentioned earlier, the stability of this type of model is related to the sample. If the sample is single, the test method is relatively simple and can be selected. Otherwise, the control parameters of the test machine need to be adjusted at any time (that is, conventional P, I, D Parameter) This is almost impossible to imagine for a tester who is not an automatic control professional. Therefore, as a whole, in addition to the specific requirements for the control method, it is not easy to choose to do the test of plastic materials.
3, simple electric pull because of plastic tensile strength is a very important indicator of the mechanical properties of plastics inspection, in the previous years, there are not many types of plastic, the application is not a very wide period, the mechanical properties of plastics test items are still relatively single The corresponding standards are not perfect either. In this period, the structure was very simple, the use was very simple, and the performance index was very poor. However, the single-purpose tensile tester using a motor as a power source for a single use was widely used. As its name implies, it can only be used for a single tensile test, and the data that can be processed is very limited, and the control and measurement accuracy is relatively low. Now, although it is still used in some occasions, it has gradually been used because of its relatively single function. Eliminated for the market
4, electro-hydraulic servo universal testing machine This type of testing machine is a good performance of the current test machine, because it uses electro-hydraulic servo control technology, can achieve force, displacement, deformation closed-loop control, with good control performance. Currently, metal, building materials, etc., require constant stress, constant strain, and need for creep testing. However, due to the limitation of oil flow, his test speed is low. In order to increase the system stiffness and ensure the stable operation of the closed-loop control, the stroke of this type of testing machine is small, and the operation is complicated and the expansion configuration is difficult. The models below 10KN are few, so it is not suitable for the test of plastics and rubber materials.
5, manual hydraulic universal material testing machine This type of testing machine is the "first ancestor" of the testing machine family, it has a long history, easy to use, low price, large tonnage. As the name implies, manual hydraulic pressure indicates that it is an open-loop control and has poor performance. The operation process is completely dependent on the operator's operating level. In addition, because of its mechanical structure and hydraulic loading principle, its loading speed is determined and the test stroke is small. At present, the smallest model of this type of testing machine is 50KN, so its low-load measurement accuracy is very low, and its expansion configuration capability is very poor. Generally, it is used only when conducting structural component tests or simple material performance tests, such as pulling out connecting parts. , tensile strength of steel bars and other occasions
Here are some kinds of testing machines for reference:
1, conventional electronic universal material testing machine 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, nut as the actuator, to achieve the test machine moving beam speed control, it operates Simple, the tester's requirements are not high, the test trip can be customized according to need, although the control mode is relatively single, only a speed control method, but its control accuracy and control range is very high. Take Regel's testing machine as an example, the speed adjustment range can reach 0.001mm/min ~ 1000mm/min, stepless speed regulation, control accuracy can reach 0.5, small tonnage model is easy to achieve. For friction coefficient, the full load is only 5N. It has a great deal of configuration flexibility, can be equipped with different tonnage sensors, fixtures, accessories to achieve a multi-purpose, to complete the pull, pressure, bending, shearing, peeling, tearing, friction coefficient, twisting and other functions. Throughout the relevant standards for the inspection of the mechanical properties of plastics, almost all the requirements for the control methods of the testing machine are speed control. Therefore, regardless of the control method or the speed range, the test stroke and the tonnage of the testing machine, these models are all plastic mechanics. The first choice for performance testing.
2, three closed-loop electronic universal material testing machine This type of testing machine has a wide range of conventional electronic universal testing machine speed, large test stroke, flexible configuration features, but also has the advantages of electro-hydraulic servo testing machine force, displacement, deformation control . Therefore, it is a kind of testing machine with better performance, but due to the force control and deformation control, the stability of the machine is closely related to the rigidity of the host and the rigidity of the sample. The tonnage of general plastic testing machine is small, so the rigidity of the main machine is low, and the rigidity of the sample itself is not too large. Therefore, these testing machines rarely have the following 10KN models, while the following 10KN models are plastics. most commonly used. As mentioned earlier, the stability of this type of model is related to the sample. If the sample is single, the test method is relatively simple and can be selected. Otherwise, the control parameters of the test machine need to be adjusted at any time (that is, conventional P, I, D Parameter) This is almost impossible to imagine for a tester who is not an automatic control professional. Therefore, as a whole, in addition to the specific requirements for the control method, it is not easy to choose to do the test of plastic materials.
3, simple electric pull because of plastic tensile strength is a very important indicator of the mechanical properties of plastics inspection, in the previous years, there are not many types of plastic, the application is not a very wide period, the mechanical properties of plastics test items are still relatively single The corresponding standards are not perfect either. In this period, the structure was very simple, the use was very simple, and the performance index was very poor. However, the single-purpose tensile tester using a motor as a power source for a single use was widely used. As its name implies, it can only be used for a single tensile test, and the data that can be processed is very limited, and the control and measurement accuracy is relatively low. Now, although it is still used in some occasions, it has gradually been used because of its relatively single function. Eliminated for the market
4, electro-hydraulic servo universal testing machine This type of testing machine is a good performance of the current test machine, because it uses electro-hydraulic servo control technology, can achieve force, displacement, deformation closed-loop control, with good control performance. Currently, metal, building materials, etc., require constant stress, constant strain, and need for creep testing. However, due to the limitation of oil flow, his test speed is low. In order to increase the system stiffness and ensure the stable operation of the closed-loop control, the stroke of this type of testing machine is small, and the operation is complicated and the expansion configuration is difficult. The models below 10KN are few, so it is not suitable for the test of plastics and rubber materials.
5, manual hydraulic universal material testing machine This type of testing machine is the "first ancestor" of the testing machine family, it has a long history, easy to use, low price, large tonnage. As the name implies, manual hydraulic pressure indicates that it is an open-loop control and has poor performance. The operation process is completely dependent on the operator's operating level. In addition, because of its mechanical structure and hydraulic loading principle, its loading speed is determined and the test stroke is small. At present, the smallest model of this type of testing machine is 50KN, so its low-load measurement accuracy is very low, and its expansion configuration capability is very poor. Generally, it is used only when conducting structural component tests or simple material performance tests, such as pulling out connecting parts. , tensile strength of steel bars and other occasions