Interference phenomenon and countermeasures in the process of lateral core pulling
Interference is a common problem in the operation of the lateral core-pulling mechanism of injection molds, impacting production efficiency and product quality. This phenomenon typically manifests as unexpected collisions or jamming between the core-pulling component and other mold components during movement. This can lead to mold wear at best, and product rejection or even mold damage at worst. For example, when the slider returns to its original position after completing the core-pulling motion, if the trajectory of the ejector pin or ejector plate overlaps, this can cause interference. This is particularly true in complex cavity molds, where the interlocking operation of multiple lateral core-pulling mechanisms is more likely to cause this problem. Interference not only increases downtime for maintenance but also significantly increases production costs. Therefore, it is crucial to thoroughly analyze its causes and develop effective countermeasures.
The causes of interference during lateral core pulling can be traced back to the three levels of design, manufacturing, and operation. During the design phase, if the motion timing matching between the core pulling mechanism and the ejection system is ignored, or if the stroke of the slider is miscalculated, it will lay the hidden dangers for interference. For example, when the reset action of the slider is later than the retraction action of the ejector, the intersection of the two in space will inevitably lead to a collision. Insufficient precision in the manufacturing process is also an important reason. For example, the parallelism deviation of the slider guide rail and the dimensional error of the core pulling mechanism parts will cause the actual motion trajectory to deviate from the designed trajectory, thereby causing interference. In addition, improper parameter settings during operation, such as excessive core pulling speed or excessive ejection pressure, may also lead to uncoordinated mechanism movement and induce interference problems.
For design-level issues, the key to preventing interference lies in optimizing motion timing and spatial layout. Designers need to use 3D modeling software to dynamically simulate the core-pulling mechanism and ejection system to ensure that the motion trajectories of the various components do not overlap. For example, the use of a “pre-reset mechanism” can cause the ejection system to retract before the slider resets, fundamentally avoiding motion conflicts between the two. At the same time, the core-pulling distance of the slider should be reasonably calculated, and sufficient safety clearance should be reserved. Generally, a clearance value of no less than 0.5mm is recommended to offset manufacturing and assembly errors. For complex molds with multi-directional core pulling, a sequential control mechanism can be used to control the order of each core-pulling action through hydraulic or pneumatic components to ensure coordinated movement.
In the manufacturing and assembly process, control accuracy is the key to reducing interference. When processing key parts such as sliders and guide grooves, it is necessary to ensure that their dimensional tolerances and form and position tolerances meet the design requirements, especially the parallelism and verticality of the guide rails. It is recommended to use precision grinding to control the error within 0.01mm. During the assembly process, the movement clearance of the slider should be fine-tuned by adjusting the gasket or screws to ensure that the slider moves smoothly without jamming. In addition, limit switches or sensors can be installed in areas prone to interference. When an abnormal movement trajectory of the component is detected, the shutdown signal is triggered in time to avoid hard collisions. For molds that are used for a long time, the wear of the core pulling mechanism needs to be checked regularly, and severely worn guide sleeves, sliders and other parts need to be replaced in time to prevent movement deviation due to excessive clearance.
Standardized management during operation and maintenance can also effectively reduce the risk of interference. Operators must set the core pulling speed, pressure, and stroke parameters in strict accordance with the process regulations to avoid motion imbalances caused by improper parameter settings. During the mold trial stage, the injection volume and core pulling stroke should be gradually increased, and the movement status of each mechanism should be observed in slow motion. If any abnormality is found, the machine should be stopped and adjusted in time. During daily maintenance, the sliding parts of the core pulling mechanism need to be lubricated regularly to keep the moving parts well lubricated and reduce friction resistance. At the same time, a mold maintenance ledger should be established to record the content of each inspection and the parts replaced to facilitate tracing the root cause of the problem. For complex molds, a motion timing diagram and an interference checklist can be made, and each item should be checked against the checklist before each production to ensure that each mechanism is in normal working condition.
