1. Loading method of pad printing machine
Loading with vibration plate:
The vibration plate is mainly composed of hopper, chassis, controller, linear feeder and other parts. The controller makes the electromagnet of the vibration plate generate an alternating magnetic field, driving the hopper to vibrate in the vertical direction, and the hopper also has torsional vibration around its vertical axis. These vibrations make the parts rise along the spiral track in the hopper. The parts are screened and sorted during the rising process, and finally sent to the designated position in an orderly manner through the linear feeder for the next step of processing or assembly.
Automatic feeding with robotic arms
It is to use robotic arms to complete the grabbing and conveying of materials and realize the automatic loading process. The robotic arms generally have multiple joints and can move flexibly. When working, the parameters such as the movement path, speed, and grabbing action of the robotic arms are pre-programmed. It can use the end effector (such as suction cups, grippers, etc.) to accurately grab materials according to the set program.
Push plate feeding mechanism:
For regular products, you can first use the stacking method to store the products, and then use the push plate mechanism to push the products one by one to the printing position. The so-called feeding device is to change the disordered state of the product into an ordered state to achieve continuous pad printing of the product.
2. Pre-press device of pad printer
• Flame treatment device: The flame treatment device oxidizes the polyolefin product by igniting the flame generated by the mixture of combustible gas and compressed air, introduces polar groups, and improves the adhesion of the ink.
• Plasma treatment device: Oxygen and nitrogen in the air will produce plasma under high frequency and high pressure conditions. Plasma has high energy and reacts physically and chemically with the substances on the surface of the product to remove oil and impurities, increase surface roughness and activity, and improve ink adsorption.
• Electrostatic dust removal device: Some products are prone to adsorb dust in the air due to static electricity. The electrostatic dust removal device can adsorb dust and impurities on the surface of the substrate, which can effectively improve the clarity and integrity of the printed pattern.
• Pre-coating device: Some products may need to be coated with a layer of chemical coating first to isolate the inert substances on the surface of the product, improve the surface properties of the substrate, and make the ink adhere and dry better. Suitable for some special materials or substrates with special requirements for printing effects. For example, PP water wiping device.
3. Printing system of pad printer:
1) Control interface
Pad printers commonly have microcomputer operation panels and touch screen operation panels. The microcomputer panel is mainly composed of various function buttons, and the touch screen operates the pad printer in a human-computer interactive input manner. If the structure of the pad printer is relatively simple, the microcomputer operation panel is preferred. If the structure and action of the pad printer are relatively complex, the touch screen operation panel can be used. Generally speaking, the program of the microcomputer operation panel has been pre-written and cannot be changed, but the program of the touch screen will contain multiple pages, which can be modified and updated later.
2) Ink supply and scraper system
The printing ink layer of the pad printer is relatively thin. In order to improve the hiding power, the pad printing ink usually requires a pigment with a very high color concentration. The high color concentration will affect the penetration of ultraviolet light. Therefore, for a long time, the development of UV pad printing ink has been slow. The ink used by the pad printer has always been mainly solvent-based ink.
The pad printer has two ink supply systems:
Ink tray ink supply system
The oil basin ink supply system is mainly composed of an ink tray and a scraper. The ink basin is a container open to the air for holding ink. The ink will be applied to the steel plate by the ink roller, and the scraper is used to remove the ink outside the image area of the steel plate. The ink is exposed to the air and has a certain impact on the environment.
Ink cup ink supply system
The oil cup ink supply system mainly includes an oil cup and a push cylinder. The oil cup is a closed or semi-closed container for holding ink. There is an opening at the bottom that contacts the printing plate. The sliding of the oil cup on the steel plate plays the role of supplying ink to the image area of the printing plate and scraping ink to the non-image area. The oil cup seals the ink in a small space, which can effectively reduce the volatilization of solvents, thereby reducing the amount of ink used, and has a certain effect on environmental protection. Therefore, it is often sold to developed countries in Europe and the United States.
3) Pad head cleaning device
The pad printing machine pad head cleaning device is mainly used to clean the pad head of the pad printing machine to ensure the printing quality.
The most commonly used cleaning device is to install a tape pulled by a motor in the area where the pad head moves. The pad printing pad passes over the tape and is pressed down on the tape to simulate the printing action under the command of the operation panel. The ink remaining on the surface of the pad head will be removed by the tape, which plays a role in cleaning the pad head.
4. Drying device of pad printing machine:
Hot air drying device
• Working principle: The air is heated by the heating element to form hot air, and then the hot air is blown to the surface of the printed matter by the fan to make the solvent in the ink evaporate quickly.
Infrared drying device
• Working principle: The infrared rays emitted by the infrared radiator are directly irradiated onto the ink on the surface of the printed matter, so that the ink molecules absorb the energy of the infrared rays, generate thermal vibrations, accelerate the volatilization of the solvent in the ink, and achieve drying.
Ultraviolet drying device
• Working principle: The ultraviolet drying device is mainly composed of ultraviolet lamps, reflectors and power supplies. When the ultraviolet lamp emits ultraviolet rays, the photoinitiator in the ink absorbs the energy of ultraviolet rays, generates free radicals, and triggers the polymerization reaction of the monomers in the ink, so that the ink is quickly solidified and dried. When using UV pad printing ink and UVLED pad printing ink, an ultraviolet drying device should be configured.
5. Pad printing machine unloading method:
Conveyor belt unloading
• Method description: The pad printing machine is connected to the conveyor belt, and the printed products are conveyed to the designated location through the conveyor belt. The speed of the conveyor belt can be adjusted according to the working efficiency of the pad printing machine, and the conveying process is relatively smooth.
Robot arm unloading
• Method description: Use a robotic arm to grab the printed product and place it in the designated unloading area. The robot's movements can be precisely programmed to accommodate different product shapes and placement requirements.
