The connecting rod pre-reset mechanism is a crucial auxiliary device in injection molds. Its primary function is to ensure that the ejector mechanism resets before the side core pulling mechanism during mold opening and closing, thereby preventing interference between the two and ensuring proper mold operation. This mechanism consists of key components, including a connecting rod, rocker arm, slider, and guide post. These components are precisely connected and coordinated to form a coordinated and orderly motion system. At the start of mold closing, a drive device fixed to the fixed mold drives the connecting rod, which in turn pushes the slider along the guide post via the rocker arm, ultimately achieving premature reset of the ejector mechanism and facilitating smooth operation of the side core pulling mechanism.
The operating principle of the linkage-type pre-reset mechanism is based on the lever principle in mechanical transmission and the kinematic characteristics of a planar linkage mechanism. When the mold begins to close, the fixed and movable molds gradually approach each other. A cam or push rod mounted on one side of the fixed mold contacts the drive rod in the linkage-type pre-reset mechanism, exerting a certain thrust. This thrust is transmitted through the connecting rod to the rocker arm, causing it to rotate about a fixed axis. The other end of the rocker arm is connected to the reset lever of the ejection mechanism. As the rocker arm rotates, the reset lever is pushed upward, driving the ejector plate, ejector pin, and other ejection components back to their initial positions. During this process, the motion trajectory and speed of each component are precisely calculated to ensure that the reset action is timely and smooth, without impacting other mold components.
When designing a connecting rod pre-reset mechanism, multiple factors must be considered to ensure the reliability and stability of its performance. The first is the strength and rigidity of the mechanism. Since each component needs to withstand a certain amount of impact and extrusion force during operation, high-strength alloy materials must be selected, and their mechanical properties must be improved through processes such as heat treatment. The second is the coordination of movement. Through reasonable size design and assembly adjustments, the movement of components such as the connecting rod, rocker arm, and slider must be coordinated to avoid jamming or incomplete movement. In addition, the wear of the mechanism must also be considered. Lubrication devices should be installed at key moving parts to reduce friction loss between components and extend the service life of the mechanism.
In practical applications, the link-type pre-reset mechanism is widely applicable to injection molds with complex structures, particularly those featuring side core pulling and inclined ejector mechanisms. For example, in automotive parts molds, complex product shapes often require core pulling in multiple directions. In these situations, the use of a link-type pre-reset mechanism ensures that the ejector mechanism is accurately reset before the core pulling, preventing collisions and damage between mold components. Furthermore, this mechanism offers advantages such as reliable operation and fast response, effectively improving injection molding production efficiency and product quality. However, regular inspection and maintenance of the mechanism are necessary during use to promptly identify and eliminate potential faults.
With the continuous development of the injection mold industry, the performance requirements for linkage-type pre-reset mechanisms are becoming increasingly stringent. In recent years, the adoption of advanced technologies such as computer-aided design (CAD) and finite element analysis (FEA) has enabled designers to more precisely optimize the mechanism’s structural parameters, improving its motion accuracy and load-bearing capacity. Furthermore, the application of new materials and manufacturing processes has enabled significant advancements in linkage-type pre-reset mechanisms in terms of lightweighting and increased strength. In the future, with the integration of intelligent manufacturing technologies, linkage-type pre-reset mechanisms are expected to achieve self-monitoring and adaptive adjustment, further enhancing their reliability and intelligence in injection molding production.
