A master-slave generalized predictive synchronization control for preheating process of multi-cavity hot runner system

As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.

基于 Moldflow 的汽车中控台框架翘曲变形分析及优化

以某汽车中控台框架为研究对象,测量试模样品发现其翘曲变形量超过了装配要求。通过Moldflow软件模拟了该塑件实际的注塑过程,翘曲变形量的模拟值与实测平均值的最大误差为5.98%,发现该塑件翘曲变形的主要因素为冷却不均和收缩不均。本文在原物料中添加质量分数为25%的玻璃纤维以及优化工艺参数后,翘曲变形量的模拟值与初始方案相比降低了86.22%。试模验证表明,优化后的翘曲变形量模拟值与实测平均值的最大误差为4.35%,证明了Moldflow软件模拟分析的准确性。试模后各检测点的最大翘曲变形量降到了1.6 mm以下,较优化之前降低了80%以上,为类似大型复杂注塑件的翘曲变形分析及优化提供了思路。

基于Moldflow软件对薄壁件某塑料喷嘴的注塑方案优化研究

喷嘴注塑产品的质量和性能很大程度上由注塑方案和工艺参数所决定,不当的注塑方案和工艺参数会导致充填不足、熔接线过多、翘曲变形量大等问题。为了可以减少生产周期,节约生产成本,利用三维软件UG对喷嘴进行建模,基于模流分析软件Moldflow软件对喷嘴注塑产品进行分析和优化,通过比较点浇口和侧浇口两种方案的分析结果,最终确定该产品点浇口的方案更好。并通过设计正交实验,得到优化后的工艺参数。

基于Moldex 3D与正交试验的离心泵泵头注塑工艺优化

以商用离心泵泵头为研究对象,运用Moldex3D模流分析软件对其注塑成型过程进行了模拟。根据产品的结构特点设置了三种浇口方案,通过对注塑过程的模拟分析选出最佳方案来获得模具设计思路并预测制品成型后可能存在的质量问题。结果表明,平衡进浇方案的制品具有最好的综合性能,制品的翘曲变形量为1.588 mm,体积收缩率为2.444%。确认最佳浇口方案后,将充填时间(A)、保压时间(B)、冷却时间(C)和模具温度(D)作为实验因素,采用田口法构建五因素四水平的正交试验来获得最佳工艺参数,并使用极差和方差分析对结果进行置信度检测。以翘曲总位移结果为主要权重对象,通过极差分析确定了成型参数的最优组合为A_(1)B_(1)C_(1)D_(1),方差分析则验证了极差分析的结果置信度高于99%。相较于初始方案,制品的翘曲变形量从1.588 mm降低至1.214 mm,降低了23.6%;冷却时间降低至10 s,降低了40%。得知模流分析技术的使用让产品的质量和生产效率都得到了明显的优化,为预测塑件性能、降低生产成本、提高生产效率提供了一种可行的方式。

基于Moldflow的车身后护板微孔发泡注塑工艺多目标优化

使用Moldflow软件模拟车身后护板注塑工艺,采用正交试验及灰色关联分析结合熵权法优化注塑工艺参数,并进行了实际试模验证。结果表明:使用微孔发泡注塑成型可实现车身后护板减重及降低翘曲变形量;优化的工艺参数为熔体温度235℃,模具温度35℃,充填时间3.5 s,充填体积百分比92%,初始气体含量1.2%(w),所制零件总质量为1362.2 g,z方向翘曲变形量为1.006 mm,较采用微孔发泡默认工艺组合分别减少了18.4 g,0.478 mm;采用灰色关联分析结合熵权法对工艺优化能满足产品减重和降低翘曲变形量的要求。

基于Moldflow的排水泵过滤网注塑工艺优化与模具设计

利用Moldflow对塑料排水泵过滤网的注塑成型过程进行仿真,通过对其结构分析制定了合理的浇口位置和冷却水路。利用三因素三水平正交试验,研究了熔体温度(A)、充填压力(B)和开模时间(C)对于塑件翘曲变形的影响,得出较优的工艺参数组合为A_(1)B_(3)C_(3),即熔体温度220℃,充填压力80%,开模时间6 s,此时塑件的最大翘曲变形量为0.632 8 mm,与优化前相比降低了10.37%。最后依据Moldflow的分析结果,利用UG软件对注塑模具的结构进行了设计,根据塑件卡扣的结构特点,型腔采用整体式结构,型芯设计为组合式(主型芯+滑块)结构,并采用三组“斜导柱+滑块”式侧向抽芯机构解决脱模问题。为实现顺序脱模,借助尼龙塞以增加定模板与动模板之间的开模阻力,设计了内置式“小拉杆+拉杆套”结构的定距分型机构;考虑到塑件形状和模具结构与成本,设计了沿塑件侧壁轮廓排布的圆推杆脱模机构;为避免气纹、气穴等缺陷的形成,在型腔处设计了排气槽结构。该模具结构设计较为合理,可为其他结构相似塑件的模具设计提供有益参考和指导。

基于Moldflow的汽车把手气辅注塑工艺多目标优化

汽车内饰把手是典型的棒状类零件,常采用气体辅助注射成型(GAIM)技术进行生产,以满足把手强度和轻量化要求。由于GAIM技术的成型参数多,塑件成型质量控制难度大,通过运用Moldflow模流仿真分析并结合Taguchi试验方法,以塑件的气体穿透长度和横截面最小壁厚为质量目标来优化成型工艺参数,选择熔体温度、模具温度、气体压力、气体保压时间和预注射量5个主要因素进行正交试验,采用极差分析研究上述5个工艺参数对气体穿透长度和横截面最小壁厚的影响规律,应用多目标综合平衡法得到优化的工艺参数组合,即熔体温度为250℃、模具温度为50℃、气体压力为10 MPa、气体保压时间为10 s、预注射量为75%。通过实际GAIM验证,塑件气体穿透效果良好,满足穿透长度和横截面最小壁厚的要求,塑件质量减轻25%以上,并具有良好的表面质量和尺寸精度,能够显著缩短成型周期,节约塑料材料,提高生产质量和效率,并满足汽车轻量化要求。

国内外复合材料工艺设备发展述评之六——模压成型

本文分析了复合材料模压成型工艺所用设备的发展历程,指出其优缺点,并对今后发展提出建议。

基于Moldflow优化的计算机CPU涡轮风扇模具设计

结合CPU涡轮风扇的注射成型要求,采用CAE辅助分析优化得到了塑件的成型方案为1模1腔、正面中心轴顶端进浇模腔布局,单点热嘴环形热浇口浇注。利用分层抽芯的方法将单个涡轮叶槽的脱模采用上、中、下3层滑块的顺序实施抽芯的方法进行侧抽芯脱模,从而得到整个涡轮风扇叶槽的所需脱模机构为27个滑块机构,分别为上层9个上滑块机构、中层9个中滑块机构、下层9个下滑块机构。根据滑块机构的抽芯驱动需要,将模具的整体结构采用一种假三板模结构,分3次开模,第一次开模用作下层9个滑块机构的侧抽芯驱动;第二次开模用作上层9个滑块机构的侧抽芯驱动;第三次开模用作塑件的完全脱模,第三次开模打开后,随着中层9个油缸驱动9个中滑块侧抽芯动作的完成,塑件自动脱落而实现完全脱模。结合涡轮风扇叶槽难以脱模的实践难题,设计了3层滑块机构按序抽芯,根据模具开模提供的驱动进行设计,有效地解决了涡轮风扇塑件的成型难题,机构动作可靠,生产效率较高。

Irregular initial solidification by mold thermal monitoring in the continuous casting of steels:A review

Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.

Effects of the Water-Cement Ratio and the Molding Temperature on the Hydration Heat of Cement

The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and 0.45,and the molding temperature was specified at 10 and 20℃.The experimental results show that,as the water-binder ratio increases,the value of the second temperature peak on the temperature curve of the cement paste decreases,and the age at which the peak appears is delayed.The higher the water-cement ratio,the higher the hydration heat release in the early period of cement hydration,but this trend reverses in the late period.There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio,and this law can be observed at both molding temperatures.With the increase in the molding temperature,the age of the second temperature peak on the temperature curve of the cement paste will advance,but the temperature peak will decrease.The higher the molding temperature,the earlier the acceleration period of the cement hydration began,and the larger the hydration heat of the cement in the early stage,but the smaller the total heat in the late period.A subsection function calculation model of the hydration heat,which was based on the existing models,was proposed in order to predict the heat of the hydration of the concrete.

Investigation of bubbles escape behavior from low basicity mold flux for high-Mn high-Al steels using 3D X-ray microscope

During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the mold.In which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid slag.In contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive information.Therefore,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding times.The results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles increases.In addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases.In one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the large.These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.

Elimination of cracks in stainless steel casings via 3D printed sand molds with an internal topology structure

The important supporting component in a gas turbine is the casing,which has the characteristics of large size,complex structure,and thin wall.In the context of existing 3DP sand casting processes,casting crack defects are prone to occur.This leads to an increase in the scrap rate of casings,causing significant resource wastage.Additionally,the presence of cracks poses a significant safety hazard after the casings are put into service.The generation of different types of crack defects in stainless steel casings is closely related to casting stress and the high-temperature concession of the sand mold.Therefore,the types and causes of cracks in stainless steel casing products,based on their structural characteristics,were systematically analyzed.Various sand molds with different internal topology designs were printed using the 3DP technology to investigate the impact of sand mold structures on high-temperature concession.The optimal sand mold structure was used to cast casings,and the crack suppression effect was verified by analyzing its eddy current testing results.The experimental results indicate that the skeleton structure has an excellent effect on suppressing cracks in the casing.This research holds important theoretical and engineering significance in improving the quality of casing castings and reducing production costs.

Dependence of Lower Molding Temperature Limit and Molding Time on Molding Mechanism in Dental Thermoforming

Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechanisms on the lower molding temperature limit and molding time in dental thermoforming. Ethylene vinyl acetate resin mouthguard sheet and two thermoforming machines;vacuum blower molding machine and vacuum ejector/pressure molding machine were used. The molding pressures for suction molding were −0.018 MPa for vacuum blower molding and −0.090 MPa for vacuum ejector molding, and for pressure molding was set to 0.090 MPa or 0.450 MPa. Based on the manufacturer’s standard molding temperature of 95˚C, the molding temperature was lowered in 2.5˚C increments to determine the lower molding temperature limit at which no molding defects occurred. In order to investigate the difference in molding time depending on the molding mechanism, the duration of molding pressure was adjusted in each molding machine, and the molding time required to obtain a sample without molding defects was measured. The molding time of each molding machine were compared using one-way analysis of variance. The lower molding temperature limit was 90.0˚C for the vacuum blower machine, 77.5˚C for the vacuum ejector machine, 77.5˚C for the pressure molding machine at 0.090 MPa, and 67.5˚C for the pressure molding machine at 0.45 MPa. The lower molding temperature limit was higher for lower absolute values of molding pressure. The molding time was shorter for pressure molding than for suction molding. Significant differences were observed between all conditions except between the pressure molding machine at 0.090 MPa and 0.45 MPa (P < 0.01). A comparison of the differences in lower molding temperature limit and molding time due to molding mechanisms in dental thermoforming revealed that the lower molding temperature limit depends on the molding pressure and that the molding time is longer for suction molding than for pressure molding.

基于Moldflow的带金属嵌件电机齿轮盖注塑工艺优化

汽车雨刮电机齿轮盖采用注射成型技术,内嵌齿轮盖中的3根金属嵌件起到导通电流的作用。在注射成型过程中要确保各金属嵌件有一定的间距,以保证电机正常工作。为了验证设计的方案是否满足设计要求,采用模流分析软件Moldflow对齿轮盖注射成型过程进行分析,以准确掌握金属嵌件的变形情况。初始方案仿真计算结果显示,注射成型后用于接地的嵌件31在XY平面内变形量过大,可能存在搭接短路风险,不满足设计要求。针对嵌件31变形量过大的问题,分析可能的原因,从注射成型工艺参数和嵌件定位方案两方面进行优化。在满足设计要求前提下,通过正交试验法获得最优的模具温度和熔体温度,仿真结果表明:将注射成型工艺参数中的模具温度调整为80℃,熔体温度调整为265℃,嵌件31的变形量减少27.3%;将嵌件31的定位方式更换成穿孔式定位,可有效增加嵌件的定位可靠性。两种优化方案共同实施后,嵌件31的最大变形量从0.55 mm降低到0.05 mm,变形量减小90.9%,满足设计指标要求,提升了设计产品的可靠性。

Non-Darcy Flow in Molding Sands

Darcy’s law is widely used to describe the flow in porous media in which there is a linear relationship between fluid velocity and pressure gradient. However, it has been found that for high numbers of Reynolds this law ceases to be valid. In this work, the Ergun equation is employed to consider the non-linearity of air velocity with the pressure gradient in casting sands. The contribution of non-linearity to the total flow in terms of a variable defined as a non-Darcy flow fraction is numerically quantified. In addition, the influence of the shape factor of the sand grains on the non-linear flow fraction is analyzed. It is found that for values of the Reynolds number less or equal than 1, the contribution of non-linearity for spherical particles is around 1.15%.

Determination of Optimal Manufacturing Parameters for Injection Mold by Inverse Model Basing on MANFIS

Since plastic products are with the features as light, anticorrosive and low cost etc., that are generally used in several of tools or components. Consequently, the requirements on the quality and effectiveness in production are increasingly serious. However, there are many factors affecting the yield rate of injection products such as material characteristic, mold design, and manufacturing parameters etc. involved with injection machine and the whole manufacturing process. Traditionally, these factors can only be designed and adjusted by many times of trial-and-error tests. It is not only waste of time and resource, but also lack of methodology for referring. Although there are some methods as Taguchi method or neural network etc. proposed for serving and optimizing this problem, they are still insufficient for the needs. For the reasons, a method for determining the optimal parameters by the inverse model of manufacturing platform is proposed in this paper. Through the integration of inverse model basing on MANFIS and Taguchi method, inversely, the optimal manufacturing parameters can be found by using the product requirements. The effectiveness and feasibility of this proposal is confirmed through numerical studies on a real case example.

控制技术在现代挤出过程中的应用

概述了挤出工艺过程,指出现代挤出生产过程对节能、省力、稳定性的要求日益增高。为保证高速挤出的质量和节约原材料,都需要高精度的控制系统,发达国家的挤出机已普遍采用现代电子和计算机控制技术,对整个挤出过程的工艺参数如熔体压力及温度等参数进行在线检测,并采用微机闭环控制。分析了挤出工艺的控制特点及控制系统的工作原理,并指出开发新一代智能挤出设备的紧迫性。

基于Moldex3D的油漆桶桶盖注塑成型过程分析

利用模流分析软件Moldex3D模拟油漆桶桶盖注塑成型过程,研究桶盖模具使用阀式热流道与开式热流道两种不同浇注方案的成型差异,并结合仿真结果设计热流道。通过设计Taguchi DOE实验的因素与水平,优化桶盖产品的注塑工艺参数。结果表明:设定工艺参数为熔体温度250℃,保压时间2 s,冷却时间18 s时,产品没有短射、包封等外观质量问题;优化后的注塑工艺参数有效降低了产品的冷却时间。

Effect of CeO_2 on heat transfer and crystallization behavior of rare earth alloy steel mold fluxes

To improve the heat transfer capability and the crystallization property of the traditional mold flux, CaF_2 was replaced with B_2O_3. Then, the influences of CeO_2 on the heat transfer and the crystallization of the CaF_2-bearing mold flux and the new mold flux with 10 wt% B_2O_3 were studied using a slag film heat flux simulator and X-ray diffraction(XRD). The results revealed that the addition of CeO2 reduced the heat transfer by increasing the solid slag thickness and the crystallization of two mold fluxes. However, CeO_2 had less effect on the B_2O_3-containing mold flux compared with the CaF_2-bearing mold flux. According to the analyses, the CeO_2 contents in the CaF_2-bearing mold flux and the B_2O_3-containing mold flux should not exceed 8 wt% and 12 wt%, respectively. Therefore, these experimental results are beneficial to improve and develop the mold flux for casting rare earth alloy steels.