Analysis of Squeeze-Type Internal Pressure Testing Technology for Herbal Tea Cans

On the assembly line, rows of herbal tea cans advance at a constant speed. Belts on both sides gently squeeze the cans, and pressure sensors transmit data in real time. This system can inspect 72,000 cans per hour, with a rejection rate of up to 99.9%.

In the beverage industry, especially for products like herbal tea that often require secondary sterilization, internal pressure testing of cans is directly related to product quality and safety. Squeeze-type pressure testing technology, as an efficient and accurate online testing solution, plays an indispensable role in this field.

This contact-based testing method effectively identifies products with abnormal pressures due to poor sealing or improper sterilization processes, ensuring that only qualified products enter the market.

1. Inspecting Principle and Technical Advantages

The core of squeeze-type internal pressure inspecting technology lies in the precise integration of mechanics and sensing. The equipment uses double-sided belts to squeeze the moving cans. Pressure sensors behind the belts capture real-time pressure feedback signals from the cans during the squeezing process.

The control center analyzes the pressure data and compares it with a preset acceptable range. If the pressure inside the can is abnormal (too high or too low), the system immediately issues a command, triggering the rejection mechanism to separate defective products from the production line.

The greatest advantage of this contact-based inspection method over non-contact inspection is its ability to accurately identify abnormal can pressures after secondary sterilization. For products such as herbal tea that require secondary sterilization, the sterilization process can cause changes in can pressure due to factors such as temperature and sealing. Squeeze-type inspection systems can effectively detect these changes.

Common pressure issues in herbal tea cans typically stem from several factors:

• Inaccurate liquid nitrogen filling

• Poor sealing

• Inappropriate secondary sterilization process parameters

These issues can cause can pressure to deviate from safe ranges, potentially causing product deterioration or can deformation.

2. Core Components of Inspection Equipment

A complete squeeze-type pressure inspection system consists of three core components: a human-machine interface (HMI), a pressure detection unit, and a rejection actuator.

The HMI is the interface between the operator and the equipment. It typically uses a color touchscreen with a bilingual Chinese and English menu for convenient parameter setting and data monitoring. Tower lights and an operator interface provide intuitive equipment status displays, allowing production line personnel to quickly understand equipment operating conditions.

The pressure detection unit, the core of the system, utilizes high-precision dynamic tracking sensors capable of detecting minute pressure changes. These sensors transmit real-time data to a PLC (programmable logic controller) for analysis and judgment.

The rejector, the system's actuator, is typically driven by a pneumatic cylinder. Upon receiving a rejection signal, it accurately knocks defective cans off the production line, achieving a rejection accuracy rate of 99.9%.

The equipment's technical specifications demonstrate its high performance: it can inspect up to 72,000 cans per hour, consumes only 0.5 kW of power, operates in an operating environment of 0-45°C, and can even operate stably at altitudes exceeding 3,000 meters.

3. Workflow and Key Operational Points

The standardized operating procedure for the squeeze-type internal pressure tester begins with equipment preparation and parameter setting. Operators must configure the corresponding pressure acceptance range, inspection speed, and other parameters on the human-machine interface based on the specifications of the herbal tea cans.

During the inspection process, cans are smoothly fed into the inspection area by a conveyor belt, where double-sided belts apply constant pressure to the cans. This squeezing action requires precise control, ensuring effective sensing of the can's internal pressure while avoiding excessive pressure that could cause deformation.

The sensor reading pressure data is a critical step in the entire process. As each can passes through, the system records its pressure value and compares it to a preset standard. This fully automated process enables real-time monitoring of each product.

When a product with abnormal pressure is detected, the system accurately records its location. When the can reaches the rejection position, the rejector immediately activates, knocking the defective product off the production line. This synchronized rejection mechanism ensures continuous production line operation.

Operators are required to regularly check the equipment's operating status, including sensor sensitivity and rejector accuracy. Comprehensive data logging capabilities enable the storage of multiple sets of rejection data, providing a basis for quality traceability and process optimization.

4. Quality Assurance and Industry Applications

Controlling the internal pressure of herbal tea cans directly impacts product safety and shelf life. Appropriate internal pressure maintains the can's shape, prevents deformation caused by external impact, and inhibits microbial growth, ensuring a consistent flavor.

From a mechanical perspective, thin-walled cans exhibit specific stress distribution patterns. According to the principles of material mechanics, hoop stress is twice as great as axial stress (σ₁ = pr/t, σ₂ = pr/2t). This characteristic makes the can body more susceptible to circumferential deformation.

Internal pressure testing is crucial for quality assurance in several ways:

Preventing defective products: Promptly identifying and rejecting products with abnormal pressures to avoid market complaints.

Process monitoring: Consecutive instances of defective products can alert front-end equipment (such as liquid nitrogen filling machines) to malfunctions.

Quality data statistics: Long-term pressure data provides a basis for production process improvements.

In the herbal tea production industry, extrusion pressure testing machines have become a key quality control point on the production line. They enable 100% in-line testing in high-speed production environments, significantly improving product quality.

With the development of Industry 4.0 technologies, modern internal pressure testing equipment also supports network remote control, enabling remote data monitoring and fault diagnosis, laying the foundation for the development of smart factories.

With the advancement of intelligent manufacturing technology, the new generation of internal pressure testing equipment is integrating more data collection and analysis capabilities. In the future, we can expect inspection systems to not only eliminate substandard products but also provide real-time feedback to adjust front-end production processes, achieving more precise quality control.

For herbal tea manufacturers, investing in advanced extrusion internal pressure testing technology is not only a necessary measure to ensure product quality, but also a strategic choice to enhance brand credibility and mitigate market risks. In the increasingly competitive beverage market, excellent quality control remains the cornerstone of winning consumer trust.