提高支架压铸模寿命的途径

以某支架压铸模为例,介绍了压铸模失效的主要形式。针对模具结构、材料及其热处理等影响模具寿命的主要因素,提出了改进模具结构设计、选用优质模具材料并进行正确的热处理等措施,明显提高了支架压铸模寿命。     

An optimization of injecting system in die casting

1. IntroductionDie castings are widely used because of their highstrength and good performance. Die casting is oftenapplied in magnesium-aluminum alloys, especially forthose thin-walled components with complicate shape,because of their excellent casting ability [1].Die casting is a complex process containing severalstages. Considering the design of the vent gate and overflowin the mold, Garber simulated the tilling process [2,3]. Andhe considered the changes of melt when cast using aplunger. …     

Numerical simulation of thermal stress field for die casting dies of aluminum alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｄｉｅｃａｓｔｉｎｇｐｒｏｃｅｓｓ,ｔｈｅｄｉｅｓｅｘｐｅｒｉｅｎｃｅａｓｅ ｒｉｅｓｏｆｃｏｍｐｌｉｃａｔｅｃｈａｎｇｅｓ.Ｔｈｅｔｅｍｐｅｒａｔｕｒｅｏｎｔｈｅｃａｖｉｔｙｓｕｒｆａｃｅｓｏｆｄｉｅｓｉｎｃｒｅａｓｅｓｒａｐｉｄｌｙｄｕｅｔｏｃｏｎｔａｃｔ ｉｎｇａｎｄｗａｓｈｉｎｇｂｅｔｗｅｅｎｔｈｅｍｏｌｔｅｎｍｅｌｔａｎｄｄｉｅｓ,ａｎｄｔｈｅｈｏｔ ｙｉｅｌｄｓｔｒｅｎｇｔｈｉｎｃｏｎｔａｃｔｚｏｎｅｏｆｔｈｅｃａｖｉ ｔｙｉｓｒｅｄｕｃｅｄｒａｐｉｄｌｙ .Ｉ…     

Interfacial heat transfer behavior at metal/die in finger-plated casting during high pressure die casting process

Heat transfer at the metal-die interface has a great influence on the solidification process and casting structure. As thin-wall components are extensively produced by high pressure die casting process(HPDC), the B390 alloy finger-plate casting was cast against an H13 steel die on a cold-chamber HPDC machine. The interfacial heat transfer behavior at different positions of the die was carefully studied using an inverse approach based on the temperature measurements inside the die. Furthermore, the filling process and the solidification rate in different finger-plates were also given to explain the distribution of interfacial heat flux(q) and interfacial heat transfer coefficient(h). Measurement results at the side of sprue indicates that qmax and hmax could reach 9.2 MW·m~(-2) and 64.3 kW ·m~(-2)·K~(-1), respectively. The simulation of melt flow in the die reveals that the thinnest(T_1) finger plate could accelerate the melt flow from 50 m·s~(-1) to 110 m·s~(-1). Due to this high velocity, the interfacial heat flux at the end of T_1 could firstly reach a highest value 7.92 MW·m~(-2) among the ends of T_n(n=2,3,4,5). In addition, the q_(max) and h_(max) values of T_2, T_4 and T_5 finger-plates increase with the increasing thickness of the finger plate. Finally, at the rapid decreasing stage of interfacial heat transfer coefficient(h), the decreasing rate of h has an exponential relationship with the increasing rate of solid fraction(f).     

铝合金壳盖压铸工艺优化研究

通过对铝合金壳盖压铸件进行实体造型,采用铸造数值模拟软件Z-Cast对铝合金壳盖压铸过程的压力场、速度场和温度场进行数值模拟,根据模拟结果分析浇注系统和溢流槽尺寸的合理性,重新设计、优化浇注系统的形状和布置位置,得到合理的压铸方案。对于铝合金压铸件结构和压铸工艺设计有着重要的指导意义。     

CAE模拟分析在前盖压铸模设计中的应用

应用Anycasting软件对铸件的填充过程、凝固过程和模具温度场进行模拟分析,利用模拟结果优化模具结构,尽量避免模具设计对铸件质量产生的不利影响,降低铸件缺陷产生的概率,缩短产品开发周期。     

Determination of interfacial heat transfer coefficient and its application in high pressure die casting process

In this paper,the research progress of the interfacial heat transfer in high pressure die casting（HPDC）is reviewed.Results including determination of the interfacial heat transfer coefficient（IHTC）,influence of casting thickness,process parameters and casting alloys on the IHTC are summarized and discussed.A thermal boundary condition model was developed based on the two correlations：（a）IHTC and casting solid fraction and（b）IHTC peak value and initial die surface temperature.The boundary model was then applied during the determination of the temperature field in HPDC and excellent agreement was found.     

Temperature change and stress distribution analysis of die surface in Al-alloy die casting process and experimental study on die heat check

The temperature change of the die surface in practical aluminum alloy die casting process was analyzed, and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze the stress distributions along the die surface in detail. Equipment was designed to test the thermal state of the die steel in different thermal loading conditions. The results of stress analysis showed that, the value of thermal stress （maximum 1.5 GPa） caused in the die filling and die spraying stages was larger than the mechanical stress （maximum 85 MPa） caused in the die locking stage. The results of the thermal check experiment showed that there were three stages of die dissolving, and that the stress distribution shown by the samples＇ cracking routine was close to the die surface stress analysis.     

发电机支架压铸模大滑块的卡滞与改进措施

从材料、液压抽芯器、热变形、冷却、受力等5个方面分析了发电机支架压铸模大滑块卡滞产生的原因,通过采取改进滑块导滑结构、增加限位装置并疏通冷却水道,有效解决了发电机支架压铸模大滑块的卡滞问题。     

局部增压技术在发动机支架压铸模中的应用

阐述了局部增压技术的原理及其在发动机支架压铸模中的应用,通过挤压机构的设计及挤压工艺参数的调整,解决了发动机支架压铸模设计的问题,满足了特殊结构和高质量要求的铸件生产,提升了铸件成型质量。     

铝合金轮毂压铸模温度场数值分析

运用有限元分析软件ProCAST对压铸模进行了压铸过程模具温度场分析,研究了模具预热温度、浇注温度对模具温度场的影响。结果表明,模具型腔表面温度受金属液充填的影响较大,距型腔表面距离超过20mm后,模具温度受金属液的影响较小。模具预热温度影响模具内的温度梯度和升温速率,预热温度越高,型腔表面升温速率越小,模具内的温度梯度越小。浇注温度越高,模具型腔表面的升温幅度和升温速率越大。     

基于数值模拟的发动机缸体压铸模浇注系统优化设计

针对镁合金发动机缸体设计了2种不同类型的浇注系统,运用铸造模拟软件ProCAST对2种浇注系统下铸件的充型和凝固过程进行模拟,预测了充型时间、凝固时间和铸件中可能存在的缩孔、疏松及气孔缺陷的分布与尺寸,提出了优化的浇注系统设计。结果表明:在浇注温度670℃、模具初始温度220℃、压射速度8.5m/s的条件下,扇形浇注系统设计优于梳形浇注系统设计。     

镁合金AZ91D压铸的数值模拟

运用有限元模拟软件对镁合金AZ91D零件在普通压铸与真空压铸下进行计算机数值模拟,有效的预测液态金属在充型过程、凝固过程中的流场、温度场及宏观缺陷,以此对宏观缺陷的出现进行控制,优化铸造过程。此外比较真空压铸与普通压铸对铸件气孔率的影响。结果表明,当铸造工艺参数分别为冲头压射速度2.4 m/s、浇注温度655℃、模具初始温度180℃时,与压铸相比,真空压铸能有效减少铸件的气孔率,改善铸件质量。     

一模多腔点浇口压铸模设计

介绍了一副在卧式冷室压铸机上使用的二次分型、一模多腔点浇口压铸模。浇注系统的布置及模具结构可使浇注系统自行脱落,通过理论计算确定了浇注系统的相关参数。     

微电机转子压铸模设计

给出了微电机转子实用的模具结构和压铸工艺,论述了模具的设计要点.采用镶块、镶套结构,不仅节省模具钢,而且改善了模具的排气性,提高了产品的质量.     

Performance evaluation of PVD coatings for high pressure die casting

During high-pressure die-casting (HPDC) of aluminium alloys, there is a tendency for the molten alloy to react with the tool steel die, core pins and inserts. This occurrence within the high pressure die casting (HPDC) industry is referred to as ‘soldering’. It is of concern to high-pressure die casters because of down-time due to the regular removal of the soldered layer and its detrimental affect on die life and casting quality. In this investigation, several physical vapour deposited (PVD) coatings, namely, TiN, CrN and TiCN, were evaluated for their ability to eliminate soldering during HPDC of aluminium alloys. Accelerated semi-industrial trials were carried out in a 250-t Toshiba HPDC machine using a specially designed die made of P20 tool steel with removable core pins. The results from these trials showed that PVD coatings can act as a physical barrier coating preventing any reaction between the molten aluminium alloy and the tool steel. Thus the problem of soldering on such tools as core pins can be eliminated in high HPDC of aluminium alloys. In the accelerated trials, it was found that soldering was replaced by a built-up layer of cast aluminium alloy, which was less detrimental to tool life and reduced machine down-time due to the reduced need for tool polishing. The experimental results were confirmed by conducting in-plant HPDC trials.     

覆砂金属型工艺设计及其数值模拟

论述了覆砂金属型铸造工艺及其传热机理,对其数值模拟技术进行了分析,并利用ANSYS软件模拟了球铁曲轴的覆砂金属型铸造温度场,确定了其工艺参数.     

基于Pro/E镁合金壳体压铸模设计

分析镁合金壳体的结构特点,介绍压铸模浇注系统设计,使用Pro/E软件完成铸件三维实体造型和优化的压铸模结构设计。经实际生产检验:模具在使用中操作方便、安全,工作稳定可靠,铸件质量达到要求。     

Strengthening technology and mechanism for semi-solid die casting of aluminum alloy

Combined with theoretical evaluation,an optimized strengthening process for the semi-solid die castings of A356 aluminum alloy was obtained by studying the mechanical properties of castings solution treated and aged under different conditions in detail,then,the semi-solid die castings and liquid die castings were heat treated with the optimized process.The results show that the mechanical properties of semi-solid die castings of aluminum alloy are superior to those of the liquid die castings,especially the strengthening degree of heat treated semi-solid die castingsis much greater than that of liquid die castings with the tensile strength more than 330 MPa and the elongation more than 10％,and this is mainly contributed to the non-dendritic and more compact microstructure of semi-solid die castings.The strengthening mechanism of heat treatment for the semi-solid die castings of A356 aluminum alloy is due to the dispersive precipitation of the second phase(Mg2 Si) and formation of GP Zone.     

Significance of gate geometry and injection speed on the flow behaviors of molten Al alloy during die filling

The effects of injection speed and gate geometry on the flow behaviors of molten Al alloy (Newtonian fluid) were investigated by direct observations of the flow patterns during die filling. High-speed photography was employed to record the real time flow patterns of the molten metal during the die filling sequence. Qualitative assessments of the critical gate speed were made based on the experimental results. The experimental results were also compared with results predicted based on the Reynolds number. Although the critical gate speed varies depending on the gate geometry, a gate speed of ≈0.5 m/s is considered optimal to control the flow behavior of the melt in a planar flow during die filling.