| A proportional directional valve is a key component in hydraulic system with many advantages,such as fast response speed,high accuracy and strong anti-pollution ability and so on.It has been widely applied in engineering machinery,equipment system,aviation and shipbuilding and other fields.Slide valve couples composed of a spool and sleeve are the key component of a proportional valve.Because of high accuracy,complex structure and poor working environment,there are strict requirements for its structural design,material performance,the manufacturing and assembling of parts.Selective laser melting(SLM)technology can rapidly form metal parts with complex structure by using laser to melt metal powder layer by layer.Compared with the traditional manufacturing,SLM has great advantages for the design and manufacturing of single part or small batch of hydraulic components,which can meet the developing trend of personalized customization for hydraulic components.Thus,it is important to carry out the in-depth and systematic study on the proportional valve from the perspective of structural design and manufacturing,which helps to improve the performance and realizes personalized customization for a proportional directional valve.There are great differences in the microstructure between the conventional parts and the SLMed parts,which will result in different tribological properties.Due to the frequent reversing in working,it is inevitable for slide valve couples to wear.The project makes full use of the advantages of SLM and makes an innovative design for the spool of proportional valve and completes the forming by SLM.On this basis,the simulation experiment of slide valve couples is designed to explore friction performance in the reciprocating contact.The contents of the chapters in this article are as followed:Fristly,the importantance and wide application of the proportional directional valve in the industry,as well as the characteristics and advantages of SLM technology were introduced.Through the investigation on the correlation studies at home and abroad,the study content of using SLM technology to form the valve spool and to study the friction performance in the reciprocating contact was determined.Finally,the project and the test plan were given.Secondly,the laser melting system Renishaw AM250 and the process of SLM forming were introduced.Then the article introduced two key factors that affect the quality of SLM forming:processing parameter and support.It was pointed out that the optimal combination of processing parameters and the rational configuration of the parameters for the support are crucial for the SLMed parts to the improve quality.Thirdly,a direct-acting proportional dirctional valve is taken as the research object and its valve spool was designed by using the 3D modeling software.In the process of SLM forming,the match and control of process parameters were carried out.Combining SLM technology with traditional processing,the integrated forming and manufacturing of the spool was finally completed.Meanwhile,on the basis of fully summarizing the experience of forming the spool by SLM,we tried to design the lightweight spool and completed the forming using SLM.Finally,we performed the dynamic and static performance test on the test bench.In addition,the microstrructure and properties of the SLMed materials were introduced,and it was pointed out that it may play a positive role in the friction properties of the materials.Then,a simulation experiment on the reciprocating motion of the slide valve couples was designed and carried out based on working conditions(pressure and frequency),process parameters(exposure time)and forming way.Finally,the article summarized the research work and results and prospected the future study contents. |
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