| Heavy-duty screw pair is an important part of forming equipment, although it has the advantage of simple structure and high reinforcement ratio, but the characteristics of the great friction loss and low transmission efficiency is seriously restricts the further development of forming equipment. In recent years, with the emergence of kinds of wear-resisting and anti-friction material, SB/CF-EP (steel backing/carbon fabric reinforced epoxy)self-lubricating composite material gradually become heavy-duty friction pair material is one of the main developing direction because of its better than high specific strength, easily forming, excellent mechanical strength and friction performance advantages.At present, due to the process of SB/CF-EP composite nut was fabricated with spiral surface fabric laying and duplication molding is complex, and carbon fiber fabric forming difficulties, so restrict its application in the engineering practice. However, the self-lubricating lining of nut will show a poor mechanical strength and transmission efficiency if short-cut instead of carbon fabric through injection forming completely. This research adopts spiral single carbon fiber knitted fabric by semi-dry method integral forming, at the same time, short-cut carbon fiber as the secondary enhance body added to epoxy matrix, and then under the condition of high temperature by injection molding preparation nut under high temperature.Experiment using the composite sample formula in 50% of epoxy resin, curing agent 12.5%, diluent2.5%, plasticizer5%,5%MoS2, graphite 3.25%,talcum powder 8.25% and short-cut carbon fiber 13.5%. By comparing the vacuum treatment and short-cut fiber on the influence of carbon fabric composites mechanical properties experimental results show that the vacuum treatment to improve its resin percentage by 21.8%. In addition, the impact strength of 19.6 KJ/m2, Compression strength of 293.4 MPa, which relative to no vacuum treatment sample increased by 9.6% and 6.1% respectively. The compression strength is 11.5% higher than that of not add short-cut fiber samples.This paper studies the friction and wear properties of composite materials under different velocity, load and lubricating conditions. Experiments show that under the condition of two kinds of lubrication, F=500-2500N range of internal friction process has four stages, including adhesive wear, adhesion of abrasive wear, abrasive wear and fatigue wear, the friction coefficient decreased with increasing load. When F=500-1000N, rotate speed n=150～750r/min, the composite friction coefficient decreases with increasing rotate speed, n=750r/min when the friction coefficient of around 0.06, carbon fiber knitted fabric composite material still can maintain good friction performance under the condition of large friction speed. Analysis by SEM and EDS spectra indicate that friction couple ring surface form a thin layer of composite material transfer film when F=2000N. This film make it showed excellent friction and wear performance under heavy-duty conditions. In terms of mold release with such composite lining products, compared with no mold release agent and grease for demoulding agent composite lining sample, the casting wax for demoulding agent sample ejection force drop in 98.0% and 91.6% respectively, and lining shrinkage rate fell by 83.8% and 62.6%. The sample surface is complete, quality is better.Using injection molding equipment of steel backing carbon fiber knitted fabric composites nut prepared carbon fiber knitted fabric reinforced composites nut with casting wax auxiliary demoulding. Comparing the composite nut and copper nut transmission efficiency test experiment, the results show that this new type of composite nut has excellent abrasion resistance performance. Under the condition of oil lubrication, Q=750N, the equivalent friction coefficient uf fell by 25% compared with copper nut, transmission efficiency increased by 20%. Its transmission efficiency also increased by 56.5% than short-cut fiber injection molding nut; Q=1200N, the equivalent friction coefficient uf fell by 14.3%, and its transmission efficiency can be increased by 13.4%, a relatively short-cut fiber injection molding nut increased by 26.4%.With carbon fiber knitted mesh skeleton to strengthen body, short-cut fiber as a secondary enhancement phase, self-lubricating ingredients including graphite, MoS2, talcum powder, the nut has prepared use injection molding method. It not only overcomes the disadvantage of complex production process but improves the mechanical strength and retained the characteristics of large bearing capacity, excellent friction properties and high transmission efficiency. The development of new steel back carbon fabric self-lubricating composite lining transmission nut have a profound significance for improve the life of equipment with energy conservation and emissions reduction. |
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