16/07/2026
In fully automatic , the tie bar (also known as the mold-moving tie bar, mechanical arm, or mold-shifting beam) is a critical load-bearing component of the clamping mechanism. Its primary function is to drive the opening and closing motion of the mold, ensuring stability and precision during mold operation.
Simply put:
The tie bar serves as the "skeleton and power transmission bridge" of a fully automatic blow molding machine, responsible for supporting the mold and performing high-speed, precise opening and closing actions.
Specific functions are as follows:
1. Support the weight of the mold
Blow molding machine molds are typically heavy, especially:
5L plastic drum mold
10L, 20L stackable drum mold
Multi-cavity bottle mold
The main beam arm must support the entire weight of the mold and maintain its levelness and stability during operation, preventing mold sinking or misalignment.
2. Achieve mold opening and closing motion
In the blow molding production process, the following needs to be completed:
Mold opens → Parison enters → Mold closes → Air blows to form → Mold opens again
The main beam arm connects to the mold shifting mechanism through:
Hydraulic system
Servo motor
Mechanical transmission structure
Drive the mold movement to achieve rapid opening and closing of the mold.
3. Ensure mold closing accuracy
Blow molding product quality is closely related to mold clamping accuracy.
The main beam arm can ensure:
✅ Precise alignment of two mold halves
✅ Uniform mold clamping pressure
✅ Reduced flash (burrs)
✅ Improved accuracy of bottle neck and product dimensions
If the main beam lacks sufficient rigidity, the following may occur:
Mold misalignment
Uneven product wall thickness
Increased flash
Accelerated mold wear
4. Improve equipment operational stability
Fully automatic blow molding machines operate at high speeds, requiring the main beam arm to withstand frequent reciprocating motion.
A high-quality beam design can:
Reduce operating vibration
Minimize mechanical noise
Extend guide rail and mold lifespan
Ensure long-term continuous production
5. Enable automated production with robotic arms
In fully automatic blow molding machines, the movement of the tie bar requires synchronization with:
Mold extrusion
Mold opening and closing
Blowing system
Robotic arm bottle handling
Precise synchronization.
For example:
The tie bar moves to open the mold.
The robot enters to remove the product.
The robot exits.
The tie bar quickly closes the mold.
Start the next production cycle.
Achieve unmanned continuous production.
6. Affecting product dimensional and weight stability
The rigidity and precision of the main beam arm directly affect:
Product opening dimensions
Wall thickness uniformity
Product weight stability
Appearance quality
Especially when producing large drum products (such as 20L stackable drums), the main beam structure becomes even more critical.
Main structural features of the main beam:
High-strength steel structure design
Precision-machined guide surfaces
High-rigidity connection structure
Anti-deformation design
Integrated with PLC automatic control system
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