In the daily production and debugging of tablet presses, mechanical and electrical faults often occur. This article explains the basic structure of the rotary tablet press, analyzes its common faults, and proposes corresponding solutions.
1. Basic Structure of the Rotary Tablet Press
The basic structure of the rotary tablet press mainly consists of the peripheral parts, worm gear box, base, pressure rollers, guide rails, motor, adjustment mechanism, feeder, and turntable.
During operation, the power transmission device must be thoroughly inspected to ensure that the turntable can rotate clockwise. Under normal working conditions, the raw granular material is fed into the feeder. Due to its own weight, the material naturally falls into the feeder's mold. The middle mold confines the material to a specific specification, and the feeder smooths it out. The pressure rollers then compress the granular material into tablets. The turntable rotates, passing through filling and pressing stages, and the tablets are formed and ejected. This is the entire tablet pressing process.
NUMBER OF PUNCH DIE:7
MAX PRESSURE:40KN
MAX DIAMETER OF TABLET:12MM
MAX DEPTH OF FILL:15MM
MAX THICKNESS OF TABLET:6MM
CAPACITY:12600 PCS/H
MOTOR:1.5KW
SED-330-15Y rOTARY TABLET PRESS MACHINE
NUMBER OF PUNCH DIE:15
MAX PRESSURE:80KN
MAX DIAMETER OF TABLET:25MM
MAX DEPTH OF FILL:20MM
MAX THICKNESS OF TABLET:8MM
CAPACITY:15000-40000 PCS/H
MOTOR:4KW
2. Analysis and Solutions for Common Tablet Press Faults
2.1 Turntable Part
The turntable is a circular disk with uniformly distributed middle mold holes and punch rod holes. During the tablet pressing process, the punches move up and down along the guide rail curves as the turntable rotates. The common faults and solutions for the turntable, a primary working part of the tablet press, are as follows:
Wear and Tear of Middle Mold Holes or Punch Rod Holes: Prolonged use can lead to deviations in the coaxial alignment of these holes, increasing friction resistance and potentially halting tablet pressing. Mild wear can be rectified using a reamer to restore coaxial alignment, but severe wear necessitates replacing the turntable.
Turntable Lift: This can affect tablet ejection or filling. Usually caused by a loose tapered locking block, the solution is to tighten the locking block or replace faulty screws.
Middle Mold Set Screws Lifting: This can damage the feeder. As the middle mold set screws are prone to wear, they should be replaced promptly to secure the middle mold.
2.2 Pressure Roller Part
The pressure roller assembly increases protection and regulates tablet pressure, consisting of upper and lower pressure rollers.
Pressure Roller Wear: Severe wear of the pressure roller's outer circumference can increase resistance at the punch rod tail, requiring replacement of the pressure roller. If the roller shaft or internal roller is worn, they should also be replaced.
Damage or Lack of Lubrication in Pressure Roller Shaft Bearings: Bearings should be regularly maintained and replaced if damaged.
2.3 Adjustment System (Pressure and Filling Adjustment) Faults
The adjustment system comprises filling and pressure adjustments.
Adjustment Failure: Unresponsive handwheel adjustments are typically due to loose screws or a jammed worm gear. Tightening screws and lubricating the worm gear can resolve this.
Unstable Filling: Uneven granulation, poor material flow, or worn punches can cause unstable filling. Ensuring adequate filling behind the feeder by addressing punch wear can resolve this.
2.4 Guide Rail Part
The guide rail ensures the punches move along the curve. Common faults due to insufficient lubrication include:
Guide Rail Wear: Punches moving with sliding friction can wear the guide rail. The guide rail is divided into upper and lower components.
Damage to Lower Guide Rail Bridge Plate: This can impact the guide rail. If lightly worn, repair with petroleum; if severely damaged, replace the plate.
Loose Guide Rail Components: Continuous operation can loosen guide rail components. Design and manufacture of the transition section should ensure smooth operation, and regular reinforcement is necessary.
2.5 Overload Protection System
Analyzing faults in the overload protection system reveals frequent alarms due to small spring pressure settings or excessive tablet pressure. Adjusting the pressure handwheel to increase spring pressure or reducing tablet pressure can address this.
3. Common Electrical Faults and Solutions
Electrical faults are also common, including:
Machine Stops Shortly After Starting: Usually caused by excessive pressure triggering overload protection. Reducing pressure and restarting can resolve this.
Oil Pump Issues: Excessive oiling contaminates tablets, while insufficient oiling causes lubrication issues. This is often due to incorrect variable frequency drive settings, which need reconfiguration.
Auxiliary Power Failure: Typically caused by circuit issues, thorough inspection and repair of the circuit are required.
Component Failures: Key failures such as unresponsive buttons, broken panels, burned-out lights, broken alarm lights, rectifier bridge failure, damaged axial fans, non-functioning counters, and speed indicators should be addressed by replacing faulty components and inspecting the circuits.
4. Other Common Issues and Solutions
4.1 Abnormal Noise
Abnormal noise may result from:
Lack of Lubrication: Friction in the reduction gearbox due to oil deficiency requires regular lubrication checks.
Turntable and Tablet Scraper Friction: Adjust the gap between the turntable and scraper.
Damaged or Dry Bearings: Replace or lubricate damaged bearings.
4.2 Weight Variation in Tablets
Weight variation can be due to:
Material Issues: Variations in tablet density due to particle uniformity and moisture require adjustment of the material formula.
Filling Amount: Ensure consistent filling by adjusting the feeder at appropriate speeds.
Punch and Die Variations: Check punch and die shapes and sizes before use to prevent mixing different sets.
5. Conclusion
In summary, maintenance, repair, and upkeep are fundamental management tasks for equipment. Therefore, personnel must continuously explore and summarize their daily work to enrich the above content, thereby extending the equipment's operational life and enhancing economic efficiency for the enterprise.