Air vent valve for a die-casting mould

高压压铸是一种用于制造各种金属部件的工艺，在这种工艺中，液态金属在高压下被注入到钢模中，在钢模中，金属与壁面接触时很快就会冻结。在金属注射过程中，模具型腔中的空气必须被排出，否则它会被困在金属零件中，产生气孔，可能需要将零件报废。在实践中，阀门安装在空气通道的出口处，使用电气、气动或液压系统来启动，允许空气排出，然后及时关闭，以防止熔融金属通过它排出。 多伦多大学将与Bholster Technologies合作开发一种阀门，允许压铸模具在注射阶段排气，同时防止液态金属逃逸。我们计划利用快速移动的液态金属的动量冲击阀门，并在熔体从阀门排气中逸出之前将其关闭。排气阀由两部分组成，一半位于动模中，另一半位于静止模中。在模腔中加工了通道，以允许滞留的空气通过排气阀排出。弹簧使阀门活塞保持打开状态。当快速流动的金属熔体填充模具型腔时，其中的空气通过打开的阀门强制进入，并通过阀门排气口排出。当熔体到达时，它被阀体的轮廓引导到弹簧加载的活塞上。这个 液态金属的高动量迫使活塞关闭，同时引导熔体远离阀门开口，从而防止液态金属通过阀门出口流动。实验将使用水作为工作流体的阀门和一个高速摄像机用来观察水通过阀门的路径。我们建议研究液体动量如何影响阀门的运动，以及阀门响应时间对液体流量变化的敏感度。

High-pressure die-casting is a process used to make a wide range of metal components, in which liquid metal is injected under high pressure into a steel mould, where it freezes very rapidly upon contact with the walls. Air in the mould cavity must be vented during metal injection or it becomes trapped in the metal part, creating pores that may require the piece to be scrapped. In practice a valve is mounted at the exit of the air passage, actuated using either an electric, pneumatic, or hydraulic system, that allows air to vent and then shuts in time to prevent molten metal from discharging through it. The University of Toronto will collaborate with Bholster Technologies to develop a valve to permit air from die casting moulds to vent during the injection phase while preventing liquid metal from escaping. We plan to do this by using the momentum of the fast moving liquid metal to impinge on the valve and shut it off before the melt can escape from the valve exhaust. The vent valve consists of two portions, one half positioned in the moving die and the other half in the stationary die. A passageway is machined in the die cavity to allow trapped air to escape through the vent valve. A spring holds the valve piston open. When the fast moving molten metal fills the mould cavity the air in it is forced through the open valve and exits though the valve exhaust. When the melt arrives it is directed by the contours of the valve body to impinge on the spring-loaded piston. The high momentum of the liquid metal forces the piston to close while simultaneously steering the melt away from the valve opening, thus preventing liquid metal from flowing through the valve exit. Experiments will be done with the valve using water as the working fluid and a high-speed video camera used to observe the path of water flow through the valve. We propose to study how the liquid momentum affects valve movement and how sensitive the valve response time is to changes in the liquid flow rate