What are the main inspection methods for pneumatic butterfly valves?
Today, the manufacturer of pneumatic butterfly valve will share with you the testing method of shock absorber: the shock absorption performance of shock absorber should be verified through the shock absorption test. Damping experiment is usually stopped only when the shock absorber is newly designed and manufactured, and it is not necessary to stop the experiment of shock absorber one by one after mass consumption; Just stop the typing experiment. However, for particularly important shock absorbers, or shock absorbers that need to stop conditioning in the shock absorption experiment before reaching the technical request, they should be tested one by one. It is better to stop the vibration reduction experiment on the whole machine, so the experimental condition is the theoretical working condition; The vibration reduction experiment can also be stopped on a special vibration reduction test bench, that is, to simulate the theoretical working conditions, artificially manufacture the vibration source, and compare the difference between the shock absorber without the shock absorber and the shock absorber installed, so as to evaluate the advantages and disadvantages of the shock absorber.
According to different situations, various vibration excitation methods can be used to artificially produce vibration sources, such as the use of eccentric wheel rotation to drive the sliding block to generate reciprocating displacement excitation, the use of centripetal force generated by unbalanced rotor excitation, the use of compressed air blower excitation, the use of loudspeaker excitation, the use of electromagnetic induction excitation, or the use of special vibration table excitation, etc. The parameters to be measured during vibration test include frequency, amplitude, velocity, acceleration, etc., and sometimes the stress or strain of some parts of the machine. Assuming that the vibration law follows a sine function (such as the vibration caused by the rotor imbalance), the speed and acceleration can be calculated by measuring the amplitude and frequency.
The above contents are sorted out and issued by Songxia Xizhen Pneumatic Butterfly Valve Co., Ltd. If you need to reprint, please indicate the source, thank you.

Analysis and discussion
The cracks of the pneumatic butterfly valve have two directions. One is the circumferential crack along the S-shaped bend, which originates from the outside as a linear source and extends along the section thickness of the hose; The other is a longitudinal (or axial) crack, which also originates from the external surface and is a linear source, and propagates along the thickness direction of the section; When the cracks in both directions intersected, the pneumatic butterfly valve finally broke. Through the microscopic analysis of the circumferential bend fracture and the longitudinal fracture, it is found that the fracture source is a line source, the source area has no obvious data defects, and the fracture propagation area is characterized by fatigue. In addition, the fracture section is thinned at different levels, and the thinnest part of the fracture section observed is only 0.02 mm (the section thickness of other non worn areas is about 0.6 mm); Although the fracture section is thinner, there is no deformation trace near the left of the fracture. It is clarified that the thinning of the section is not caused by plastic tension.
There are obvious wear marks on the surface of the steel strip near the fracture surface, and the wear characteristics are adhesive wear+abrasive wear. According to the literature, if 304 stainless steel rubs with the friction pair, the adhesive wear mechanism is also the main one, and with the stop of external friction, the surface structure will undergo martensitic transformation. Under the action of load and friction shear stress, the microhardness of 304 stainless steel increases due to the combined effect of surface grain refinement and high-density dislocation; Therefore, in this case, the microhardness near the fracture surface of the pneumatic butterfly valve is slightly higher than that of the substrate, but the progress of its microhardness cannot improve its fatigue performance. First, the hose section itself is thinner, and with the wear consumption, the section becomes thinner, and its fatigue performance decreases. In addition, the increase of surface induced martensite has no obvious effect on the wear of SUS304 austenitic stainless steel. Therefore, it can be said that although 304 stainless steel presents martensite on the surface and its microhardness increases during friction, this cannot prevent the loss of data on the surface of stainless steel sheet and the decline of fatigue strength.
In this study, in addition to adhesive wear, there are signs of abrasive wear on the surface. These abrasive particles are mainly composed of Si, O and the like. It is the dust or sediment particles brought from the outside that mixed into the gap of the pneumatic butterfly valve, and the abrasive particles aggravated the wear of the stainless steel belt. In addition to aggravating wear, sediment infiltration has also resulted in the inability of the pneumatic butterfly valve to expand and contract freely, that is, it is stuck. The local area of the pneumatic butterfly valve is stuck, which also forms the stress anomaly in other areas, which accelerates the onset of fracture in this area.
In addition, the fracture position of the pneumatic butterfly valve in this study is about the second to fourth buckle on the left of the joint (near the end of the starter), and this position is in the area with the largest amplitude and the most frequent vibration; Therefore, the main reason for its fracture is fatigue fracture caused by vibration and wear.