PET high-skew cap inspection machine

I. Project Equipment Overview

• Project Name: PET Bottle Inspection System for Cap, Anti-theft Ring, Liquid Level, and Inkjet Printing

• Project Purpose: The system provides automated inspection and rejection of PET bottles with defects in cap placement, anti-theft ring integrity, liquid level, or inkjet code quality.

• Maximum Throughput: Up to 60,000 bottles per hour

• Applicable Container: PET bottles

• Product Volume Range: 200 mL – 2 L

II. Environmental Conditions

• Altitude: Suitable for operation between 5 and 3000 meters above sea level

• Temperature Range: 5°C – 40°C

• Relative Humidity: 50% – 65% RH

• Factory Requirements: The installation site must comply with relevant national standards regarding floor flatness, load-bearing capacity, and infrastructure conditions to guarantee stable machine operation.

• Storage Requirements: After delivery, equipment and components must be stored in facilities that meet national standards. During storage, routine lubrication and maintenance are required to prevent corrosion, damage, or deformation that could affect installation, commissioning, or future operation.

III. Equipment Operating Conditions

• Power Supply: 220 V, 50 Hz, single-phase (customer-supplied). For non-standard voltages, advance confirmation is necessary, as this may impact specifications, lead time, and cost.

• Total Power Consumption: Approximately 2.4 kW

• Control Voltage: 24 VDC

• Compressed Air Requirement: 4–12 Pa (customer to provide the air pipeline connection from the source to the equipment).

IV. Equipment Description

• Installation Location: Integrated into the production line at the designated inspection point.

• Inspection Functions:

• Missing cap

• Over-height cap

• Misaligned/tilted cap

• Broken or damaged anti-theft ring

• Low liquid level

• Missing inkjet code

• Excessive or irregular inkjet code

• Detection Method:

1. As each PET bottle passes the positioning sensor, the control unit logs its ID and synchronizes the data with the encoder signal.

2. The sensor activates the camera system, which captures images of the cap, liquid level, and inkjet code. These images are processed digitally, with results displayed in real time on the HMI and simultaneously transmitted to the PLC for defect assessment.

3. If a defect is detected, the control unit issues a command to the reject mechanism, which removes the identified bottle from the production line according to its recorded ID.

4. Equipment mechanical components

5. Electrical composition of the equipment

6. Testing cabinet structure diagram

Capping liquid level detection (capping liquid level detection at stations one and three)

Inkjet printing inspection (station 2, single-camera inkjet printing inspection)

7. Cap Inspection

This module uses three CCD cameras to capture images of bottles from different angles, reducing blind spots. Special optical lenses filter light from all directions to ensure efficient image acquisition. Its primary function is to detect defective bottles such as missing caps, overhanging caps, crooked caps, and broken caps.

8. Liquid Level Detection

This module uses a CCD camera to capture liquid level images from the front, ensuring that the liquid level in the bottle is nearly horizontal when the bottle is stationary. This module employs image processing principles that render the portion below the liquid level black in the image and the portion above the empty bottle white. A special method is used to distinguish between levels below and above the specified liquid level.

9. Inkjet Printing Inspection

This module uses a CCD camera to capture images of the inkjet printing on bottles and caps from the front. It then digitally analyzes the captured images and automatically and accurately rejects bottles with unqualified inkjet printing. It is compatible with both yellow caps with black ink and black caps with white ink.

10. Detection accuracy