The cup offset printing machine is a device specially used for high-quality printing on the surface of cups. It is widely used in packaging printing in the food, beverage, cosmetics and other industries. Offset printing is an indirect printing method. Its basic principle is to use the incompatibility of oil and water to transfer the image information to the rubber blanket through the printing plate, and then transfer the image to the surface of the substrate (cup) by the rubber blanket. In cup printing, offset printing technology can achieve fine image restoration and multi-color overprinting to meet various complex printing needs. The cup offset printing machine is the key equipment to achieve this process.
1. Basic principles of offset printing
The core principle of offset printing is that oil and water are incompatible. The printing plate is divided into the image part and the blank part. The image part is oleophilic and hydrophobic, and the blank part is hydrophilic and oleophobic. During the printing process, the fountain solution is first supplied to the printing plate to form a water film on the blank part, and then the ink is supplied to the printing plate. The ink only adheres to the image part. The printing plate usually uses PS plate, which is characterized by high image precision and strong printing resistance. The function of the rubber blanket is to transfer the ink on the printing plate to the substrate, and at the same time compensate for the uneven surface of the substrate.
2. Structure and composition of cup offset printing machine
The cup offset printing machine is mainly composed of a cup feeding system, a printing unit, an ink path system, a water path system, a drying system, and a cup collection system.
Cup feeding system: The automatic cup feeding technology is adopted to ensure that the cup enters the printing unit accurately and stably. Common cup feeding methods include robot grabbing, vacuum adsorption, etc.
Printing unit: It includes a plate cylinder, a rubber cloth cylinder and an impression cylinder. The plate cylinder is installed with the printing plate, the rubber cloth cylinder is installed with the rubber cloth, and the impression cylinder cooperates with the rubber cloth cylinder to complete the ink transfer.
Ink path system: Responsible for the supply, uniformity and ink distribution of ink. The ink supply part transports the ink from the ink fountain to the uniform ink roller, the uniform ink roller evenly applies the ink on the ink distribution roller, and the ink distribution roller transfers the ink to the printing plate.
Water path system: Responsible for the supply and control of the fountain solution. The function of the dampening solution is to keep the blank part of the printing plate moist and prevent the ink from adhering.
Drying system: UV drying or hot air drying technology is used to quickly dry and solidify the ink. UV drying uses ultraviolet rays to solidify UV ink, and hot air drying uses hot air to dry ordinary ink.
Cup collection system: responsible for collecting and sorting the printed cups.
3. Cup offset printing machine workflow
The workflow of the cup offset printing machine mainly includes cup feeding, dampening, inking, transfer, drying, and cup collection.
Cup feeding: The cup is accurately fed into the printing unit through the cup feeding system.
Dampening: The dampening solution forms a water film on the printing plate to keep the blank part moist.
Inking: The ink is transferred to the image part of the printing plate.
Transfer: The image on the printing plate is transferred to the surface of the cup through the rubber cloth.
Drying: The ink is quickly solidified by UV drying or hot air drying.
Cup collection: The printed cups are collected.
4. Key technologies of cup offset printing machine
Curved surface printing technology: By adjusting the curvature of the plate cylinder and the rubber cloth cylinder, the printed image and text can fit perfectly with the surface of the cup.
Multi-color overprinting technology: Through the precise coordination of multiple printing units, accurate overprinting of multi-color images and texts can be achieved.
Automation control technology: The PLC control system is used to realize automatic control and monitoring of the printing process.
UV curing technology: UV ink has fast curing speed, good curing effect, and is environmentally friendly.
5. Common problems and solutions of cup offset printing machine
Printing quality problems: such as ghosting, plate sticking, color difference, etc., can be solved by adjusting parameters such as printing pressure, ink viscosity, and fountain solution concentration.
Equipment maintenance problems: Daily maintenance includes cleaning the printing plate, rubber cloth, ink roller, etc., and regular inspection and replacement of wearing parts.
Troubleshooting: Common faults include cup feeding jam, printing unit jam, drying system failure, etc., which can be eliminated by checking mechanical parts, electrical circuits, control systems, etc.
6. In conclusion
The cup offset printing machine uses the principle of offset printing, combined with advanced automatic control and drying technology, to achieve high-quality printing on the surface of the cup. With the continuous advancement of technology, the cup offset printing machine will develop in the direction of high speed, high efficiency and high precision, bringing more innovation and value to the packaging and printing industry.