Shaftless printing

Shaftless printing has become a hot topic in the industry for a while. It seems that every flexo printer manufacturer must provide shaftless printing technology. Why is there so much discussion? What are the advantages of shaftless printing technology?
Since the development of flexographic technology, printers have had to face the inherent drawbacks of mechanical components, especially gears. The idea of ​​producing a flexo press without gears was proposed decades ago. However, the manufacturing of shaftless transmission systems that did not use gears only a few years ago was formally listed as an R&D project. With the concept of independent transmission and the A/C servo and flux vector drive systems being applied to the paper packaging processing industry and the printing industry, the shaftless printing press was finally available.
The transmission accuracy of the new drive system is indeed extraordinary, and its encoder resolution reaches more than 4 million pulses per revolution, which can greatly improve the accuracy of registration and print quality. Servo and vector drive systems are extremely accurate and can perform very accurate position control, proportional control and speed control. Because this new type of control system uses intelligent transmission technology and ultra-fast microprocessors, the concept of electronic transmission shafts, ie, segmented independent transmissions, has become a reality. The electronic transmission shaft technology is an advanced control technology. Ultra-high resolution encoders (in the motor) and high-speed microprocessors are used to transmit the position information of each axis in the system and accurately control the position.
Eliminating mechanical transmission components has many important implications for the flexographic press production revolution. Printing machines, which generally use gears, are generally equipped with a large-scale active motor, pulleys and belts, power shafts, transmissions, plate gears, embossing gears, and anilox roller gears; and large-gear gears are also used on satellite flexographic presses. Torsional instability of the power shaft and backlash can often affect the accuracy of registration, especially in the unstable state of acceleration and deceleration will affect the accuracy of registration. The longer the power shaft, the more gears, the greater the error. What is even more unfavorable is that as the gears and Other mechanical components begin to wear gradually under normal operating conditions, the error becomes larger and larger, the accuracy of registration gradually decreases, and finally the fatal misregistration error appears on the printed matter.
The absence of gears can clearly and completely eliminate errors caused by gears that often occur in today's printing production processes. Another advantage of not using gears is that there is no need to worry about the standard equal spacing determined by the gear pitch. As long as the printing plate is adjusted to the perimeter required by the customer and the new repeat length data is transmitted to the control center, infinitely variable repetitive printing sizes can be obtained.
In addition to further improving the printing quality, electronic transmission shaft technology and servo transmission technology have other advantages. Common geared printers require a large drive motor because all mechanical components increase friction. The use of segmented independent transmission technology not only eliminates the mechanical friction force, but also reduces the power consumption due to the use of some motors with smaller total power. It also reduces parts inventory and downtime and reduces maintenance costs. The brushless design of the A/C servo and vector motor eliminates the inherent limitations and friction of the commutator, eliminating the need for regular overhaul and replacement of brushes. The new motor has extremely stable torque throughout the operating range. Since the inertia is small, the correction speed is also faster because the circumference required for the fixed power and the magnet size are further reduced. All of this means that the rate of rejects can be reduced during acceleration and deceleration, thereby increasing economic efficiency (especially when printing short-lived jobs).
The intelligent transmission system can accurately guide each axis in the system to a predetermined position. This feature is used to automatically guide the plate in advance to the specified position when adjusting the machine. After the start of the job is completed, the accurate encoder readings are stored in the computer. The relevant data can be called up immediately when the next job is printed. Pre-registering (or “automated tuning”) can reduce commissioning time and greatly increase the economic benefits of short-run printing.
There are two types of registering without axis printing: position registration and optical dynamic registration. Positional registration is mainly a layer-to-layer register control technique used in standard non-axis flexographic printing machines, and its advantages are simple and easy. Position register technology relies on highly accurate servo drive systems and electronic drive shaft systems to achieve register alignment. In the controller, a virtual main motor is arranged facing all the motors in the independent drive system. The main motor is then programmed according to the required printer speed so that all motors in the system can be accurately controlled by the virtual main motor. This makes register accuracy high even when accelerating or decelerating.
Optical dynamic registration (for preprinted webs) has historically been difficult. This registration technique is used to apply a cold seal or anti-fog coating to the backside of the web in registration with the front print register. In the process of dynamic registration, high-speed optical sensors and reference marks on the surface of the printed web are used. The encoder used by the drive controller is mounted on a part of the work surface facing the operator. The encoder is usually mounted on a central impression drum or on a cooling roller at the outlet end of the drying device when performing the conversion. Feedback from the encoder provides speed reference data for the control system. In the technical transformation of the existing gear printing machine, a floating device needs to be installed to reduce the inherent tension and speed variation of the old system. The high-speed sensor is installed in front of or behind the printing device or coating device to provide the final control point reference position to ensure the registration accuracy. The rapid phase shifting process initiated by the controller occurs in the motor and corrects the registration error. The servo motor can immediately and accurately correct the error, eventually achieving a very high registration accuracy, and quickly restore the pull position. The Trending positioning control software based on fuzzy logic and artificial intelligence programming technology can be used to further regulate the dynamic control accuracy. The use of Trending software allows the printer to maintain a stable and consistent registration accuracy over its useful life.
Dynamic register technology can be used to expand the range of press control by precisely controlling one press with another press, or one printer behind another press. Quasi-control. In addition, it is also possible for the preprinted web to be partially coated, specially coated or otherwise processed by the printing press for the second time.
The electronic drive shaft system uses powerful industrial computers as well as many other advantages, the most important of which is to reduce the operator's workload. The graphical user interface (GUI) simplifies the complex equipment system and makes the operation of the press easy to grasp. Windows control software (similar to the ones used on home computers) allows printers without prior computer control experience to easily operate. Although experienced operators are less willing to actively adapt to new types of computer-controlled devices, they will still find the new device easier to operate if done properly. Printer manufacturers should let operators know in advance about the status of the control screen before shipping new presses, so that operators have the opportunity to ask questions or require some improvements to the control screen. The control screen can even be tailored to the specific needs of each printer.
The human-machine interface has become more efficient and practical. A computer touch screen can combine all control functions in one place, allowing the press operator to concentrate on the entire print production process. The role of the control screen is to focus the information presented to the operator on the print job around them.
The live data display screen can greatly shorten the time for tuning, so that the quality of each shift is very stable and consistent with each other. All control requirements are concentrated on one platform. Tension and temperature control, electronic drive shaft data, input/output and register data are processed by the host computer. Computer touch screens reduce the technical requirements of operators, so companies can train new operators faster and easier. The automation technology with process control function also allows equipment operators to have more time to observe the operation in time and effectively improve the quality of the final product. The alarm output data is stored in the central computer, and the operator's working intensity is effectively reduced by constantly querying the machine for errors and unsafe hidden dangers. Since the entire process parameters can be observed from the touch screen, the operator can concentrate better on looking at the entire printing process and take immediate corrective action when problems arise.
Each press operator has a special code that makes it easy to keep track of each job. When problems arise, they can be identified in a timely manner, which is conducive to training operators to continuously improve their productivity. The security protocol allows the operator to understand the programming functions of the computer at different levels. Usually the operator is only responsible for a single level of job conditions, setting job parameters, and monitoring job conditions. They can modify all the necessary functions of tuning preparation and equipment operation. And the management personnel can change the comprehensive equipment function and parameter through the advanced agreement, adopt the most recently registered password table.
Computer automation integrated process control technology is no longer a lot of manual wiring and buttons that are easily worn due to frequent use, so printers equipped with this control technology can easily adapt to changing production needs or future process needs. The latest technical parameters can be directly input to the user equipment from the original equipment manufacturer's control laboratory through the modem interface and the telephone line. This on-line transient programming technology has enabled equipment maintenance response speeds to unprecedented levels. In many cases, time-consuming telephone calls can be eliminated and production interruptions can be minimized. Man-machine interface technologies such as online assistance screens and modem diagnostics also help improve time utilization. At present, the original equipment manufacturer can access the fault diagnosis module from its headquarters through the host computer on the user's equipment to make the 24-hour technical service a reality.
Statistical process control techniques are also used on the operating platform. With dynamic data exchange software, statistical data about real-time operating conditions is automatically entered into the spreadsheet program. In this way, it is possible to continuously supervise valuable production data that are important for improving product quality and production. Next, the collected data can be analyzed and the operating parameters can be re-determined to maximize product quality and yield. At present, the enterprise IT department can easily monitor the business activities in the production plant, which will also have a greater impact on production, procurement and sales business arrangements. Some new presses can even bring real-time communication capabilities to customers through satellite equipment. Really omnipotent.
The technology we have long dreamed of has now finally become a reality. Shaftless printing and integrated process control technologies can dramatically change the face of the printing industry. However, each of us has the responsibility and obligation to make full use of this advanced technology. After all, computers are just tools. Human factors - how to use tools - can really make our printing companies and the entire printing industry reach an unprecedented level of advanced development. (US) Matthew Tilkemeyer