Timing Control Logic of Rotary Long Thread Demolding Mold
Demolding of injection-molded long thread products mainly depends on rotary thread core shaft to screw out threads. For long thread travel, disordered action timing easily triggers thread scratches, component deformation, tooth breakage and slider interference. Rational planning of motion sequence for rotary mechanism, mold opening/closing and ejection system forms the foundation of stable mass production for long thread molds. Combined with structural characteristics, this article sorts out the complete timing control logic and implementation key points.
1. Timing Control Logic in Mold Opening Phase
After packing and cooling cycles, the mold enters mold opening sequence triggered by the injection machine opening signal. Primary parting is executed firstly, and moving and fixed mold halves separate slowly. Sufficient safety clearance is reserved to prevent thread stress caused by component adhesion on fixed mold. The rotary mechanism remains inactive before mold opening reaches target position to avoid plastic thread plastic deformation caused by twisting force when the component is still trapped in fixed mold cavity. After mold opening stabilizes and clamping pressure fully releases, pre-preparation signal is triggered. The rotary motor receives standby command, and the encoder completes zero reset to check shaft jamming and proper clearance of gear or chain transmission. The core principle in this phase is "parting first, standby afterwards". Rotation start before full mold opening is strictly prohibited to prevent plastic deformation from unilateral torsion. Mold opening adopts low-speed startup, uniform medium movement and end buffer mode to reduce impact load transferred to threaded components.
2. Core Timing Control Logic of Rotary Thread Demolding
After receiving full mold opening confirmation signal, the formal rotary demolding phase begins, which is the most critical link in the whole sequence. Theoretical rotation cycles are calculated based on effective thread length and pitch and programmed as travel limit parameters. Soft startup mode is adopted for rotary mechanism to avoid instantaneous torque impact tearing plastic threads. Encoder continuously feeds back real-time position during rotation, and torque load is monitored simultaneously. Rotation will pause and trigger alarm once load exceeds threshold to prevent mold jamming and thread seizure. Demolding is divided into two timing stages. In the early rotary stage, the component is restricted by the cavity to stay static while the core shaft screws out relatively. When thread withdrawal reaches safety travel, timing program activates micro follow-up ejection to counteract axial suction between shaft and component, avoiding co-rotation of plastic parts together with the core shaft. After reaching preset rotation cycles, delay confirmation is executed to verify full separation between thread and component. The rotary motor is locked immediately to prevent secondary surface scratches caused by inertial reverse rotation.
3. Timing Control Logic of Mold Closing and Mechanism Reset
After component removal, reverse sequence of mold opening and demolding is activated for reset and closing. The rotary mechanism reverses firstly to return the thread core shaft to initial assembly zero position. Encoder verifies origin alignment to ensure accurate matching between initial thread tooth and cavity. After zero reset confirmation, the ejection system fully retracts, with ejector pins and blocks returning to original position to eliminate mold closing interference risks. The injection machine receives mold closing permission only after collecting all mechanism reset signals. Low-speed buffer section is set in mold closing travel to avoid displacement of thread core shaft caused by high-speed impact. Complete interlock protection is built for the reset sequence. Mold closing command is blocked if the thread shaft fails to return or ejection components are not fully retracted, preventing severe hard collision and core shaft breakage from logical level.
Conclusion
Timing control of rotary long thread molds establishes a complete mechanical interlock system covering mold opening preparation, rotary demolding and mold closing reset. The sequence order, signal trigger condition and coordinated regulation of speed and torque directly influence plastic appearance yield and mold service life. The core control idea is hierarchical action execution, position signal interlock and segmented speed adjustment. Closed-loop control is realized via encoder position feedback and load monitoring. Parameters including delay time and rotary speed can be fine-tuned according to material characteristics and thread length during production debugging, while the fundamental action sequence cannot be arbitrarily modified. Strict implementation of this timing logic effectively reduces common defects such as thread scratches, sticking and mechanical interference, continuously improving production stability of long thread molds and lowering maintenance frequency and production cost.
