The Study On Industrial Sewing Machine Needle Bar Based On The Air Bearing Lubrication Oil-free And Exercise Performance

As the requirement of industrial sewing machine with high speed and no oil is put forward, the transformation of shaft sleeve bearing needle bar in the thorn cloth institutions into gas float type is the key breakthrough to realize oil free lubrication.The Pre-researched 4 holes/week type shaft sleeve although realized air flotation oil free, but the high speed movement of the needle bar have higher requirements to the stiffness and stability of air floating bearings, therefore, the realization of high speed of sewing machine and high stiffness of air bearing sleeve are the two key goals, has the significant practical significance.The author firstly established the 3D model of sewing machine head part to simulate the needle bar movement, and carries on dynamic analysis under load, get the the changing curve of the needle bar position, velocity, reaction with the movement time, which is the basis of gas dynamic numerical calculation in the late.Considering the cumulative interaction force between the various connection parts of sewing machine finally transferred to the needle bar completely to the motion direction shift by rigid connection column, which influences the realization of the high-speed sewing machine.Therefore, the author will transform the rigid connection column into a precision micro displacement device composed of flexible hinge - flexible connection device, to weaken the impact of external forces on the motion of the needle bar, which create conditions for the realization of high speed. Firstly, designing the structure of the flexible device, and second, to establish the parameters that have the largest influence on its performance, then we calculate the achieved micro-displacement range of needle bar drived by the device output and the intensity of the device under external force, finally, through the ANS YS analysis, use its value to prove the rationality of the design theory, and analyze the numerical accuracy. Contrast found that error is small, the simulation analysis results are close to the theoretical calculation results, so this device has great reliability.In order to improve the stiffness and stability of the air shaft in needle high-speed, on the basis of previous studies, the author has designed two kinds of new flotation sleeve:one kind is 6 hole / week type shaft sleeve, it not only has higher gas bearing capacity compared, but also improves the rigidity than that of previous research on small hole type bushings;The other is a slit type shaft sleeve, its biggest characteristic is with high stiffness in a certain bearing capacity.First of all, the design of structure and technical scheme on the flotation of the shaft sleeve, and the establishment of the physical model of the needle bar overall offset and inclined lower in the shaft sleeve, film surface fitting; secondly, the derivation of air flotation lubricating static control equation, dynamic control equation and the static characteristic expression, and set the gas film boundary conditions and flow balance relationship;Then, through respectively discrete difference on the static and dynamic control equation, carries on numerical calculation and analysis to the needle bar static characteristics under the whole eccentric and dynamic characteristics of the needle bar under inclined with the help of Matlab using dichotomy iteration.The design-process manufacturing finished goods, and through the design and build a test platform to test multiple gas floating collar bearing capacity value at the eccentric and record, comparing experiment data after processing with theoretical results, to verify the reliability of theoretical numerical analysis. By contrast, the experimental measured value are similar to the theoretical value, explained that the designed sleeve can meet the expected requirement.