Optimization Design Of Shape Following Cooling System For Injection Mold And Research On Additive Manufacturing Method

Injection molding is the most widely used production method for plastic products.The cooling process of the plastic product during injection molding accounts for three-quarters of the entire injection molding cycle.The rapid and uniform solidification of the plastic during cooling is crucial to the quality of the molded product.Therefore,the design of the cooling system of the mold has the greatest impact on the entire injection molding process.Conventional injection molds are limited by the traditional mechanical processing methods and usually adopt linear cooling pipelines.This pipeline is prone to uneven cooling for complex structured workpieces,leading to warpage and deformation of the plastic parts.Cooling pipelines that closely and uniformly surround the plastic part’s shape can significantly improve the warpage caused by traditional cooling methods and achieve rapid and uniform cooling.However,the complex structure of conformal cooling waterway presents a challenge for traditional mold manufacturing processes.The application of additive manufacturing technology in mold manufacturing can fundamentally solve the processing problems of complex structured parts and achieve the manufacture of cores and cavities with conformal cooling pipelines.This can achieve the goal of conformal cooling in injection molding production,thereby improving cooling efficiency and the quality of the molded product.The detailed research on this topic is as follows:（1）This paper designs a conformal cooling system for a complex-structured injection molding part,achieving fast and uniform cooling of the plastic part.Using three-dimensional assisted design and finite element mold flow analysis software,this study conducts a specific analysis of the structural characteristics,material properties,and molding processes of the complex-structured plastic part.Based on the thermal flow calculation theory of the mold cooling system and the construction principles of the cooling pipelines,three sets of conventional cooling schemes,including linear,spray tube,and baffle types,and one set of conformal cooling system,are designed.By conducting“filling+cooling”mold flow analysis on the four cooling systems,the effectiveness of the designed conformal cooling waterway is verified.The analysis results show that the conformal cooling system has better cooling performance than the other three cooling schemes in various temperature indicators.In particular,the"part average temperature"of the conformal cooling system is 30℃,4.9℃,and 4.6℃lower than that of the linear,spray tube,and baffle types,respectively.（2）This study further optimized the design of the initial conformal cooling system and the process parameters during injection molding,resulting in better cooling performance and higher quality of molded parts.To address the issues of high temperature accumulation and hot spot concentration identified in the cooling analysis of the initial conformal cooling system,the structure of the cooling channels was optimized and redesigned.To mitigate the impact of the filling and packing processes on the cooling performance and quality of molded parts,the optimal combination of injection molding process parameters was determined using the Design of Experiments（DOE）module in Moldflow.Finally,a mold flow analysis was performed on the optimized conformal cooling system with the optimized cooling channel structure and process parameters during the“cooling+filling+packing+warpage”stages.The analysis results showed that the warpage caused by uneven cooling was reduced to only 0.0127mm after optimization,which was a 4%decrease from the previous result.The cooling performance and quality of the molded parts were significantly improved.（3）An optimal set of additive manufacturing process parameters for the conformal cooling mold cores and cavities was obtained through orthogonal experiments and variance analysis.Based on the Ansys Additive manufacturing simulation platform,a 4-factor 4-level L₁₆（4⁵）orthogonal experiment was conducted for the process parameters of laser scanning speed,powder spreading thickness,laser power,and substrate temperature.The residual stress and deformation of the printed parts were selected as evaluation indicators,and the significance of the impact of each parameter and the optimal parameter level values were comprehensively analyzed using variance analysis.The optimal process parameters obtained were:scanning speed of 2500mm/s,powder spreading thickness of 70μm,laser power of100W,and substrate temperature of 120℃.Compared with the average values of the 16orthogonal experiment results,the residual stress and deformation of the printed parts were reduced by 55%and 48%,respectively,using this optimal parameter set,indicating better processing quality.（4）The final optimized design results were FDM printed,and the molding effect was good.