Research On Squeeze Casting Technology Of Excavator Bucket Teeth

As a part of the excavator that is in direct contact with the material,the bucket tooth is often operated under complicated and severe working conditions,which belongs to the wearable part in the excavator.Therefore,the tooth tip is required to be with high hardness and superior wear resistance,and other parts with mechanical properties of strong toughness.However,the bucket tooth produced by traditional forming process can no longer meet the increasing demands of people for their mechanical properties.In this thesis,the technical idea of forming the bucket tooth with squeeze casting process was proposed,and the complete process scheme of squeeze casting for the bucket tooth was designed.Firstly,the low carbon alloy steel ZG1HCrMnSiNi was selected as the research object.The microstructure,hardness,toughness and other mechanical properties of ZG14CrMnSiNi under different pressures were studied by using SEM,EDS,JB-50 impact testing machines and other testing equipment,which the influence rule of pressure on the microstructure and mechanical properties of ZG1HCrMnSiNi was obtained.Besides,the positive effects of squeeze casting on improving the microstructUre and the mechanical properties of the material were analyzed.Secondly,through the analysis of the bucket teeth structure,the special die and forming process scheme for the squeeze casting of bucket teeth were designed.Then,by using the ProCAST process simulation software to simulate the squeeze casting process,and observing and analyzing the temperature field,stress field and casting defects,the feasibility of the scheme was verified.Finally,a process scheme that meets the requirements for the use of squeeze casting machine was designed according to the forming process and die schemes of squeeze casting.The conclusions obtained are as follows:(1)Squeeze casting specific pressure has a significant effect on improving the size of ZG1HCrMnSiNi.With the increase of the pressure,the crystal grains became smaller gradually,while the effect of pressure on the grain was gradually decreased.Compared with the traditional metal casting process,the microstructure and grain of the material under the squeeze casting process was more uniform.Under as-cast condition,the grain size of the metal casting ferrite was the largest.At the pressure of 60MPa,the size of squeeze casting sample ferrite was reduced by 33.0%compared with the metal casting ferrite,and the size was reduced by 43.9%at the pressure of 120MPa.and 54.5%at the pressure of 150MPa.Under heat-treated condition,the grain size of the squeeze casting sample ferrite was reduced by 46.0%compared with metal casting ferrite at the pressure of 60MPa?60.0%at the pressure of 120MPa.and 69.6%at the pressure of 150MPa.(2)After comparing the hardness,impact toughness and wear resistance of materials at different pressure,it was obtained that with the increasing of the pressure,the hardness and impact toughness of the material will be gradually increased.At the pressure of 150 MPa,the minimum wear of the sample was 0.4697g at lOOmin,which the wear resistance was improved by nearly 40.0%compared with the metal casting,and increased by 10.7%at the pressure of 60MPa,and 13.6%at the pressure of 120MPa.It indicated that the hardness and toughness of the sample increased the wear resistance,and the mechanical properties of the ZG14CrMnSiNi material were significantly improved under the action of refining grains.(3)The horizontal molding with one mold and four cavities is adopted,arranging with symmetric rectangle in the center to separate the upper and lower molds.The pressing scheme is indirect pressure filling and direct pressure feeding,and the lifting scheme is that the main pressing head drives the ejector,(4)The optimal process plan is obtained by computer simulation:when the specific pressure is 150 MPa.the filling speed is 46.6 mm/s.the pouring temperature is 1560?,and the preheated temperature is 200?.In summary,through the study of the microstructure and property of the bucket tooth material,it was confirmed that the bucket tooth made by the squeeze casting process had obvious advantages in improving wear resistance,reducing microstructure defects and improving the service life,and the performance has been greatly improved compared to metal casting.Meanwhile,through the design and simulation of the process scheme,the feasibility of the squeeze casting in the actual production of the bucket tooth was confirmed.