Following a step-by-step breakdown and focusing on the function of core components, this article breaks down the working principle of an oral liquid filling machine in detail, making it easy to understand and covering key aspects:
I. Overall Core Logic
The oral liquid filling machine is essentially an automated and precise liquid dispensing device. Its core revolves around a closed-loop process of "bottle supply - positioning - liquid supply - quantitative dispensing - filling - bottle dispensing." Through the coordination of mechanical structure and electrical control, it achieves "filling immediately upon bottle arrival and immediate departure after filling," while ensuring consistent dosage in each bottle and preventing leaks or overflows.
II. Detailed Working Principle (including the function of core components)
1. Bottle Feeding and Sorting: Arranging Empty Bottles in an Orderly Line-Up
- First, a bottle sorting machine (manual or automatic feeding) organizes the messy empty oral liquid bottles (usually brown glass or plastic bottles) into a uniform orientation (bottle neck upwards), preventing tipped or tilted bottles.
- The sorted empty bottles are then transported by a conveyor belt with guide plates on both sides to prevent bottles from veering off course.
- Before reaching the filling area, the bottles are precisely fixed directly below the filling head by a positioning mechanism (such as a dial wheel, bottle baffle, or clamp), ensuring the bottle neck is aligned with the filling head (key point: inaccurate positioning will lead to leaks or overflows).
2. Liquid Supply: Ensuring a Stable and Accurate Delivery of Oral Liquid to the Filling Head
- The oral liquid concentrate is stored in the equipment's storage tank (equipped with insulation/stirring functions; some models prevent liquid sedimentation and stratification).
- A supply pump (commonly a gear pump or plunger pump, offering high precision and stable delivery) is connected to the bottom of the storage tank. Driven by a motor, the pump delivers the concentrate to the filling pipeline at a constant pressure and flow rate.
- The pipeline is equipped with a filter (to remove minute impurities from the concentrate, preventing clogging of the filling head) and a pressure stabilizing valve (to prevent inconsistent filling volumes due to supply pressure fluctuations).
3. Dosing Adjustment: The Core of the Core, Ensuring Precise Dosing in Every Bottle
This is the crucial step determining the consistency of oral liquid dosage. The dosing principles of different models are as follows (including details):
Volumetric Dosing (Mainstream and Commonly Used):
Core Components: Metering pump (plunger pump/piston pump), measuring cup, one-way valve;
Working Process: The motor drives the plunger/piston in a reciprocating motion. When the piston retracts, the concentrate in the reservoir is drawn into the metering chamber (metering cup/pump body) through the one-way valve. The volume drawn in is determined by the "piston stroke" (the dosage can be changed by adjusting the stroke length, e.g., 10ml, 20ml); when the piston advances, the liquid in the metering chamber is pushed out by high pressure and injected into the bottle through the filling head. Each reciprocating motion corresponds to one quantitative filling, with an error controllable within ±0.1ml.
Time-Flow Rate Dosing (Mid-to-Low-End Models):
Core Components: Flow sensor, electromagnetic flow meter, solenoid valve;
Working Process: First, a stable liquid supply flow rate is determined through debugging (e.g., 10ml/s). Then, the filling time is set according to the target dosage (e.g., 10ml corresponds to 1 second). After the bottle is in place, the solenoid valve opens, and liquid is injected at the set flow rate. After the set time is reached, the solenoid valve automatically closes. Dosing is achieved through "flow rate × time". The liquid supply pressure must be kept stable throughout the process; otherwise, dosage accuracy will be affected.
Weighing Dosing (Precision Models):
Core Components: Electronic weighing sensor, PLC control system;
Working Process: After the empty bottle is positioned, the weighing sensor first weighs the "empty bottle weight" (tare). After filling begins, the weight of the liquid in the bottle is monitored in real time. When the weight reaches the target value (e.g., 10ml corresponds to 10g, converted according to liquid density), the PLC immediately issues a command to stop filling. Suitable for scenarios requiring high dosage accuracy (error ±0.05ml), it can automatically compensate for errors caused by changes in liquid density.
4. Filling Operation: Precise Injection, Avoiding Leaks
- After the bottle is positioned, the lifting mechanism (driven by a cylinder or cam) lowers the filling head. Some models have filling heads that fit snugly against the inside of the bottle neck (or are equipped with an anti-foaming sleeve) to reduce air bubbles during liquid injection (oral liquids contain active ingredients, and air bubbles can affect dosage and product stability).
- The filling head is equipped with an anti-drip device (such as a one-way valve or drip recovery tank): During filling, the valve opens, allowing for smooth liquid injection; after filling, the valve closes quickly, and any remaining droplets are recovered or blocked by a sealing gasket, preventing drips onto the bottle or conveyor belt.
- For easily oxidized oral liquids (such as those containing vitamins or traditional Chinese medicine ingredients), some models simultaneously introduce nitrogen gas during filling (nitrogen replacement) to expel air from the bottle and prevent liquid oxidation and deterioration. The filling head is equipped with a nitrogen injection channel to achieve "nitrogen purging before filling" or "nitrogen purging while filling."
5. Bottle Ejection and Linkage: Connecting to the Next Process
- After filling, the lifting mechanism raises the filling head, the positioning mechanism (clamp/wheel) releases, and the conveyor belt continues to operate, sending the filled bottles to the next process.
- Some fully automated production lines link the filling machine with subsequent equipment (stopper, capping machine, labeling machine): the filled bottles are precisely transferred to the stopper station via the wheel, where the rubber stoppers are pressed, and then sent to the capping machine to tighten the caps, all without manual intervention.
6. Electrical Control: A Complete "Brain-Driven" System
Core Components: PLC controller (equivalent to the "brain"), touchscreen (operation panel), photoelectric sensors (detecting bottle positioning), encoder (controlling conveyor belt speed);
Working Process: Operators set filling dosage, speed, nitrogen filling parameters, etc., via the touchscreen. The PLC receives signals from the photoelectric sensors (e.g., "bottle in position") and then instructs the liquid supply pump, solenoid valves, lifting mechanism, etc., to work in coordination. If abnormalities such as "no bottle" or "bottle tilted" occur, the sensors will feed back to the PLC, and the equipment will automatically stop and alarm to prevent the fault from escalating.
III. Key Auxiliary Components (Ensuring Stability and Product Quality)
- Storage Tank Insulation/Stirring: For temperature-sensitive oral liquids (such as biological agents), the storage tank has heating/cooling functions to maintain a constant liquid temperature; stirring devices (such as paddle agitators) prevent sedimentation of the raw liquid and ensure uniform composition.
- Cleaning and Sterilization: Some models feature stainless steel storage tanks, filling lines, and filling heads, supporting CIP (Clean-in-Place) cleaning (no disassembly required, high-temperature cleaning solution circulation) and SIP (Steam Sterilization) to prevent cross-contamination.
- Overload Protection: In case of insufficient liquid supply or bottle jamming, the equipment will automatically cut off power or stop operation to protect the motor and mechanical components from damage.
