The Research About The Key Technology Of Thin-walled And Low-friction Hoisting Equipment

Pneumatic hoist is the most ideal explosion-proof lifting equipment; it is widely appliedin the combustible, explosive and high-precision positioning, etc. the most common problemsfor domestic manufacturing of pneumatic hoist including: lower load ability, not sensitive tothe changes of atmospheric pressure, poor controllability, high friction and not smooth andsteady when lifting or release the load,etc. Therefore, an overall study of the key technologiesof pneumatic hoist such as the design of the structure, the sealing and friction betweencylinder and piston and the reliable of braking is necessary.The steel cylinder deformation will happened in the use of the pneumatic hoist. Theprecision of the steel cylinder and its surface roughness will affect the friction and the gasleakage of the pneumatic hoist. Therefore, a detailed design including the thickness of wall,the length of the steel cylinder and its accuracy and surface roughness is important. The thesisadopt the methods of finite element analysis to simulate the deformation of the steel cylinderunder normal working condition, by doing so, the structure of steel cylinder was optimized.The thickness of the wall is small while the accuracy of the steel cylinder and its surfaceroughness are pretty high, which makes it hard to manufacturing. In order to improve theaccuracy of the steel cylinder, we try to explore the manufacturing process of the steelcylinder and then optimize it.There is a contradictory of low friction and small leakage in the field of dynamic sealing.In order to lower the friction between the steel cylinder and the piston, we should not only tryto make the contact pressure between the steel cylinder and the piston as lower as possible,but also should we adopt the materials with a low friction coefficient. The relationship amongthe surface roughness of the steel cylinder, the contact pressure for sealing and the gas leakagebetween the steel cylinder and the piston can be figured out by using the methods of finiteelement simulation. The optimization of the piston groove size can be calculated by thecombination of that relationship and the software of Mat lab. SPGO is consist of a PTFEwear-resistant ring and an O ring.it is a much better choose to select SPGO for sealingaccording to the result of an orthogonal experiment. The result of the orthogonal experimentshows that we could not only lower the friction between the steel cylinder and piston, but also improve its performance of sealing, which means to a much more precise positioning for thepneumatic hoist.As one of the safest lifting equipment, the braking process of pneumatic hoist should bequickly, safe and reliable. The CAM and the spring is the key parts of the braking. The CAMand the spring have been designed and optimized after a detailed analysis of its force. And theprocess of braking has been simulated by using the software of ABAQUS. In this model, thespring stiffness or spring force can be solved by equivalent to the internal force of a straightrod. The result of the braking indicates that the stiffness of the spring that come fromsimulation keep pace with the stiffness of the spring that designed by the analysis the brakingprocess of the brake.The paper studies the key performance indicators of the pneumatic hoist such as loadcapacity, gas leakage and friction between the steel cylinder and the piston, the performanceof braking and the stress and strain of the steel cylinder under normal working conditions.From the studies of the key technology of the pneumatic hoist, we succeed in achieving thegoal of a small deformation of the steel cylinder, a much lower friction between the steelcylinder and piston and more reliable of braking. Therefore, the overall design of thepneumatic hoist is rational.