| Split sleeve cold expansion is an important technology for enhancing aircraft fastener holes, and split sleeve is the key of this technology. The research on split sleeve is still scarce in our country, for example, materials are not various and the thickness of sleeve is constant. Therefore, in order to expand the application fields of split sleeve, simulation and experimental analysis were combined to explore the regularities of roll forming of 301 stainless steel( the original material is 07Cr15Ni7Mo2Al),based on two-axle flexible bending technology. The main work and achievements are summaried as follows:1. Through the tensile test on 301 stainless steel strip, tensile stress-strain curves of 3/4 hard and full hard 301 stainless steel strip with different thickness were obtained in this paper.2. With the tens ile stress-strain curves of 301 stainless steel strip, simulation analysis of the roll-bending process using full hard, 3/4 hard and 07Cr15Ni7Mo2 Al stainless steel strip has been conducted. The result showed that during the manufacture of small-diameter split sleeve, full hard 301 stainless steel strip was the most difficult to process, the second was 3/4 hard 301 stainless steel strip, and 07Cr15Ni7Mo2 Al stainless steel strip was the easiest.3. Orthogonal design method was employed in simulation analys is to study the influence of strip thicknesses, outer diameters of elastic wheels and feeds of rigid axle during the roll-bending process of 3/4 hard 301 stainless steel. The optimum parameter for the roll-bending process of 3/4 hard 301 stainless steel was obtained, strip thickness was 0.4mm, outer diameter of elastic wheel was 120 mm and feed of rigid axle was 5mm.4. The experiments of roll-bending process using 3/4 hard and full hard 301 stainless steel strip were conducted to study the roll-bending rule of different diameters. And the results showed that the quality of straight split sleeves using this material was high.5. The microstructure of three materials was observed through metallographic experiment and the elemental composition inspected by EDS analysis. Moreover, the micro hardness of three materials was detected. Plasticity and strength for three materials were good and roll-bending quality was great. The hardness of stainless steel should be considered when manufacturing small-diameter split sleeve. Materials with lower hardness were prefered if other property was satisfied. |
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