Plastic soft packaging infusion leak detection technology and equipment working principle

Leak testing requirements for infusion products are very strict, because leaks can cause viruses and airborne viruses to enter (bags), which can lead to contamination and deterioration of the liquid. Infusion bottles (bags) are micropores caused by temperature or pressure, generally 10-1 micron, which cannot be detected by the naked eye, so the detection method is extremely critical.

There are generally four types of detection methods: staining test, high pressure test, discharge test, and vacuum test. Dyeing inspection will pollute products, including qualified products, which are basically not used now; pressure testing can detect leaks, but it takes a long time for micro-leakage, and leakage is not easy to be found; vacuum inspection has the advantage of comprehensive inspection of inspection products, shortcomings The speed is slow, the equipment cost is expensive; the discharge inspection speed is fast, the price is relatively moderate, and the disadvantage is that only a few special parts can be inspected.

Based on years of experience in the use and maintenance of imported leak detectors, a company has developed a test of plastic bottle infusion continuous leak detectors (high-voltage power) after two years of development, making up for the shortcomings of the other four types of equipment. After 5 years of use, the performance is reliable and works well.

1. Working principle:

The factory provides 220V50Hz mains power through the variable frequency power supply and then boosts it through the transformer. As the detection power supply, the sensor judges whether it is qualified or not, and transmits it to the industrial computer for signal processing and drives the actuator to execute. As shown in Figure 1.

The detection electrode is used to inspect the weld of the inlet portion of the plastic infusion soft bottle that needs to be tested. When the high voltage is added, the system equivalent circuit is based on Ohm's law:

For qualified products: I1=V/(R1+r+R2)

For non-conforming products: I2=V/(r+R2)

I1: Qualified product current I2: non-conforming product current
V: voltage R1: mouth impedance
r: liquid internal resistance R2: bottom impedance
If the mouth weld leaks, it is equivalent to the short-circuit impedance of the R1 port, and the difference between the test current and the non-conforming product is used as the criterion.

ΔI=I2-I1

2. Outline structure

3. Operation mode and function
3.1 Machine continuous automatic operation, industrial computer control, with manual control operation.

3.2 conveying part
The Lexno engineering plastic ball chain plate can reduce the frictional resistance and protect the plastic bottle from being scratched by friction. The friction strips of polymer materials are on both sides, and the width can be adjusted to different specifications. The conveyor can be connected with the conveyor on the front, and then separated and positioned by the servo motor controlled cylinder dial, and automatically sent to the positioning part of the leak detector. This part is made of stainless steel and engineering plastic. When replacing different specifications, only Need to replace the small positioning rod, easy to replace, the entire machine is completely replaced with different specifications of the product in a quarter of an hour.

3.3 Inspection section
Check the product mouth twice and check the bottom once.

The mouth part inspection part is specially designed. The patent application is completely different from the previous traditional leak detector electrode. The stainless steel plate is precision-cut and the wheel corresponding to the size of the bottle mouth is welded. It has the previous mouth. The acicular discharge structure of the electrode is inspected and is elastic, which can more accurately ensure that the size of the detecting electrode from the inspection site is guaranteed to be in the range of 0.5 mm. The transmission is a gear made of a polymer material that is behind, and the gear can isolate the high pressure from the machine.

II The detection distance of this part can be very small, and the detection voltage can also be reduced from the original 30 kV to 22 kV, which has the same detection effect.

III This part is also not affected by the deformation of the bottle body during the infusion sterilization process. Similarly, the detection electrode does not scratch at the seal like the conventional leak detector.

The IV conventional leak detector cannot achieve high speed due to noise problems. This part of the noise is very small, so it can reach a very fast speed. Even if the mechanical transmission part reaches 160 bottles/min, the noise is still small.

This part of V is a multi-position inspection at the same time, which can ensure that the detection time is above 0.2 seconds, which is also an important reason for improving the detection speed.

3.4 culling part: The unqualified product that has been inspected is removed by the action of the cylinder placed on the side of the conveyor. Checking the qualified product will automatically enter the following conveying mechanism to enter the following process.

4. Electrical device
4.1 Variable frequency power supply: The power supply is specially made. The input voltage is 220V/50Hz, the positive and negative wave AC power, the output is the carrier wave type, the frequency is 50Hz, the 500-700Hz adjustable wave type is loaded, and the voltage is steplessly adjusted from 0-150V.

The frequency setting and reality are completed on the panel, the working current is displayed, and three different sets of voltages can be set and displayed for convenient selection.

4.2 High-voltage transformer: special iron core and special structure are more suitable for this inspection method. The core is made of microcrystalline material, that is, microcrystalline foil with a thickness of 20 microns, which is superimposed into a 20*20 core rod. Adapting to the shape and frequency of the shape, the primary coil and the secondary coil are wound on such a rod-shaped iron core, and only the required voltage is generated, and no excessive current is passed, so even a high voltage is very safe. The life of the transformer is very high.

4.3 Detection circuit: The precision sensor is used to determine the leakage current. It contains a specially designed circuit, which can filter out the interference generated by high frequency and judge whether it is qualified more accurately and reliably.

5. Control device:

5.1PLC: Japan's Mitsubishi brand, strong anti-interference ability
5.2 touch screen: Taiwan brand, ten inches and 256 colors. Almost all display, setting and operation are completed on this touch screen including automatic operation, manual operation, jog, adjustment, setting of machine operation parameters, automatic recording and detection of product quantity, quantity of qualified products, quantity of non-conforming products, and each The number of unqualified parts was detected. The result is displayed on the touch screen and the fault alarm indication is displayed on the touch screen.

Fault alarm indication is displayed on the touch screen
5.3 Low-voltage electrical appliances: domestic Siemens brand
6. Safety protection: The high-voltage part of the machine has a protection function. When the protective door is opened abnormally, it has a self-locking function. The machine will automatically cut off the high-voltage power supply and alarm, and prompt the alarm information.
7. The detection rate of non-conforming products is 99.999%, and the false detection rate is <0.5%.