1. Introduction There are four types of speed control methods for printing machinery: First, DC thyristor speed control, mainly used in larger roll-to-roll newspaper and book printing equipment, is still widely used. Second, some equipment uses three-phase AC commutator motors for speed control, but this is no longer used. Another method is using electromagnetic speed-regulating motors, commonly known as slip-ring motors. This speed control method is quite widely used in printing machinery, although some equipment may use fixed-speed transmission. In recent years, most newly developed products, especially those requiring variable speed or stepless transmission, have adopted frequency converter speed control, even for larger printing equipment. Enterprises have generally reached a consensus that using frequency converter speed control is a symbol of improved technology in printing machinery and also a choice for energy conservation. Printing machinery differs from other machinery in that it processes substrates of various thicknesses, including paper, cardboard, film, and even thin metal materials. Printing equipment employs various printing methods (relief, planographic, intaglio, perforation, and special printing) to accurately print various colors in proportion to the specified positions on the substrate, thus forming colorful printed materials including text and images. After printing, the semi-finished products undergo extensive post-printing equipment processing to complete folding, collating, cover application, and binding of books and periodicals into paperback and hardcover editions. After newspaper printing, it requires stacking, counting, inserting pages, bundling, and distribution equipment to meet mailing requirements. Packaging materials—cardboard boxes, paper bags, self-adhesive labels, etc.—require die-cutting, slotting, coding, box making, and bag making after printing to become finished products. Substrate processing machinery can perform cutting, slitting, cross-cutting, die-cutting, hot stamping, lamination, varnishing, embossing, and coating processes to create semi-finished or finished products of different sizes, shapes, decorations, and materials. Therefore, the vast family of printing machinery and equipment, the variety of types and the diversity of processes will be a broad market for frequency converters. 2. Simple classification of printing machinery and equipment (1) Prepress plate making equipment: laser imagesetters, cameras, plate exposure machines, digital direct plate making machines, film output machines, plate baking machines, automatic plate making machines, engraving machines, etc. (2) Printing equipment: Letterpress printing presses: letterpress printing press (obsolete), self-adhesive printing press (intermittent), flexographic printing press (photosensitive resin plate), pad printing press, corrugated paper printing slotting machine, etc.; Offset printing presses: sheet-fed printing press (specifications include full sheet, half sheet, quarter sheet, eighth sheet), roll-fed printing press (newspaper, book, commercial), form printing press, business card printing press, etc.; Gravure printing presses: sheet-fed gravure printing press, roll-fed gravure printing press, banknote printing press, stamp printing press, etc.; Screen printing presses: flat screen printing press, rotary screen printing press, irregular screen printing press, etc.; Special printing presses: inkjet printing press, thermal transfer printing press, printer, electrostatic printing press, Braille printing press, etc.; Digital printing presses: all-in-one machine, in-machine plate printing press, plateless printing press (electronic ink), digital printing press, etc. (3) Post-press equipment: Bookbinding equipment: saddle stitching machine (including collating machine, stapler, three-sided trimmer), perfect binding machine, hardcover binding machine, binding machine (including straight, disc, and oval binding machines), shell making machine, sewing machine, book cover attaching machine, flattening machine, folding machine, etc.; Newspaper post-press equipment: stacking and bundling machine, dryer, newspaper distribution equipment, inserting machine, paper feeder, paper conveying equipment (keel), etc.; Packaging post-press equipment: die-cutting machine (including flatbed, rotary, and rotary-flat die-cutting methods), paper cutter, slitting machine, cross-cutting machine, box making machine, varnishing machine, laminating machine, calender, envelope machine, hot stamping machine, etc. (4) Auxiliary equipment: CNC bending machine, grinding machine, punching machine, plate bending machine, paper feeder, dryer, cooler, etc. (5) Supporting products: magnetic powder brake, clutch, special bearings for printing presses (with eccentricity and adjustable center), temperature controller, tension control system, alignment device, ink remote control device, automatic registration device, speed measuring motor, infrared heater, ultraviolet heater, automatic registration device, CNC drive system, servo motor (including micro servo motor), frequency converter, PLC programmable controller, touch screen, numbering machine, photoelectric switch, CCD camera, etc. 3. Main motion characteristics of printing machinery The main motion characteristics of printing machinery: The processing object is various flexible printing substrates. In the processing process, it is necessary to ensure that the printing substrate moves according to the specified requirements, and to complete the printing of various colors or the processing of the substrate while the printing substrate is moving. This results in two motion chains of printing machinery: paper transfer motion and printing motion, which are coordinated with each other. Taking the roll-to-roll offset printing press as an example, in order to ensure the needs of variable speed operation and printing, many of these machines still use DC speed regulation to control the two motion chains of the whole machine. To complete the printing process, several movements need to be performed, such as ensuring the operation of the jogging (plate loading, cleaning cylinder, paper feeding) process. Coaxial with the DC motor is an AC motor and a cycloidal pinwheel reducer to achieve low-speed, jogging operation. Furthermore, the water and ink supply is directly related to the printing speed, so the water and ink delivery rollers are driven by two separate DC servo motors. Several other fixed-speed motors are responsible for adjusting the plate cylinder alignment, paper loading, and the left-right position of the paper roll. To ensure printing quality, the substrate requires a magnetic powder brake to control the paper feed force, a speed-measuring motor to guide the water and ink supply, and an alignment device to control the paper path. Different types of motors also participate in these mechanisms. Other printing presses and printing machinery also have similar or proprietary process characteristics. For printing presses using various printing methods, the movement of the equipment is primarily a variable speed movement, which includes the following during operation: (1) Before leaving the factory, the equipment needs to undergo a no-load test, which includes a working operation test and a high-speed rated operating speed test; (2) A printing press is an optoelectronic integrated device, and various functional matching adjustments need to be made during assembly, such as: paper feeding double-sheet infrared control, paper feeding positioning device adjustment, paper automatic lifting adjustment, paper handover adjustment, tension control adjustment, pneumatic device adjustment, etc., all of which require low-speed operation of the equipment; (3) After the equipment is put into use, it needs to perform jogging operations such as loading printing plates, wiping printing plates, and wiping blankets during printing; (4) Before the equipment officially starts full-speed printing, it needs to complete the adjustment of functions such as slow paper feeding, printing registration, and ink-water balance. Full-speed printing can only be carried out after the printed products meet various quality requirements; (5) The length of the motion chain also needs to be adjusted according to the number of colors required for the printed products. For equipment other than printing presses, there are also different processes and different speed requirements. 4. Currently, the main products for which frequency converters are used are printing machinery and equipment. The use of frequency converters began in the early 1980s. At that time, major domestic printing machinery companies developed new products with the aim of improving their technical level and began to use frequency converter speed control devices. In order to improve the stability and reliability of the equipment, printing machinery companies generally adopted imported frequency converters. Products using frequency converters include sheet-fed offset printing presses and roll-fed offset printing presses. Later, they were extended to equipment for various printing methods and different printing sizes. Later, they were also spread to post-press binding machinery, packaging machinery and other equipment. The main products used are: (1) Sheet-fed offset printing presses and post-press binding equipment of various specifications. Sheet-fed offset printing presses can be divided into full-sheet, half-sheet, quarter-sheet and eighth-sheet printing presses according to the size of the printed paper. They are used in packaging, books and periodicals, advertising and quick printing industries, respectively. In particular, color printing presses are the backbone equipment of the printing industry. For many years, the speed control system of the equipment has used electromagnetic speed control motors. In recent years, frequency conversion speed control has become fashionable. However, some foreign companies have already launched high-end multicolor printing presses. The paper feeding system is driven by a variable frequency motor, and the printing cylinder is driven by a servo motor. The coordination between the two movements is tracked and matched by the servo motor. The functional units of this equipment, such as the paper feeder, also use independent drives. Post-press binding equipment consists of independent single machines equipped with only one frequency converter, such as three-sided book trimmers, single-head or double-head book staplers, and disc binding machines. Some post-press equipment requires more than two frequency converters. For example, an oval binding machine with ten clips requires one frequency converter to control the page-breaking vibration table and another frequency converter to control the main movement of the equipment. Another type of saddle stitching production line also requires two frequency converters to control the entire binding process of collating, binding, and cutting into books. (2) Roll paper offset printing presses of various specifications and post-press counting and bundling equipment Roll paper offset printing presses are the backbone equipment for newspaper and book printing in my country. This equipment itself is a large-scale printing production line. While completing the printing process, it can also continuously complete multiple functions such as cutting, folding, counting, and bundling. With the development of equipment technology, roll paper printing machines have also added functions such as automatic paper feeding, drying, and varnishing. However, since its inception, this equipment has always used DC thyristor rectification speed regulation, and uses a long shaft to drive each functional unit to complete the printing process. In addition to the old products, the newly developed products have completed the transformation of frequency converter speed regulation, and some new products have completely eliminated the long shaft, with servo motors, drive systems and CNC systems driving each functional unit independently, thus bringing this equipment to a new level. On these devices, frequency converters are only used for some secondary functions, such as speed regulation of water and ink. (3) Roll paper gravure printing machines and post-printing packaging equipment of various specifications This equipment has the same working mode as roll paper offset printing machines. The difference is that the gravure printing machine has a simpler structure than the former, and has a wider range of printing materials. It can print various polyester films. The equipment uses frequency conversion speed regulation and independent drive processes in the same way. This type of post-press equipment includes rewinding machines, slitting machines, laminating machines, sheet cutting machines, die-cutting machines, etc., which can be connected in line or used separately to complete post-press processing. (4) Flexographic printing machine This type of equipment is a veritable production line composed of multiple printing methods and post-press processing, but the main printing unit is photosensitive resin plate (letter plate) as the main printing function. Its speed regulation development process is basically the same as that of roll paper printing machine. In short, the equipment that originally used DC speed regulation, electromagnetic motor speed regulation, gearbox stepped speed regulation and other stepless speed regulation can basically be transformed into frequency conversion speed regulation. At present, most of the larger printing machinery equipment, high-end printing machinery products and products exported abroad use imported or Sino-foreign joint venture frequency converters, while low-end products and small printing machinery equipment use domestic frequency converters. 5. Application prospects of frequency converters In 2004, the sales of printing machinery equipment in the whole industry were RMB 6.5-7 billion, with an annual growth rate of more than 15%, of which the export of printing machinery was US$262 million, an increase of more than 50% compared with 2003. my country's printing machinery imports totaled US$1.716 billion, equivalent to approximately RMB 16 billion. The total sales revenue of printing machinery in the Chinese market was between RMB 22.5 billion and 23 billion. Major enterprise groups included Beiren Group (RMB 1.4 billion in sales in 2004), Shanghai Electric Group Printing & Packaging Machinery Co., Ltd. (RMB 1.7 billion), Zhongjing Group (RMB 400 million), and Yingkou Guanhua (RMB 100 million). With the development of printing machinery technology, exports are expected to increase year by year, and the domestic market share will grow significantly, leading to a rising demand for frequency converters. Currently, there are approximately 450 printing machinery manufacturers in China, producing over 200 different types and specifications of printing machinery. Based on current sales figures, approximately 30,000 units of equipment using frequency converters are used annually. The main motor power of equipment using frequency converters ranges from 0.4 to 82 kW. 6. Hoping for Domestic Frequency Converters to Enter the Printing Machinery Industry. According to statistics from the frequency converter industry, in the mid-1990s, there were 50 companies in China producing and selling frequency converters. Among them, 29 companies had 33 specifications of products recommended by four national ministries. Although in recent years, the products of Shenzhen Huawei, Chengdu Jialing, and Yantai Huifeng have reached a certain technical level, the market share of domestic frequency converters in China is no more than 10%. Very few manufacturers in the printing machinery industry use domestic frequency converters. The main products purchased are foreign brands such as Mitsubishi, Fuji, Yaskawa, and Hitachi from Japan, Siemens from Germany, Schneider Electric, Omron, and ABB from France. Some printing equipment manufacturers have begun to choose domestic frequency converters for their small-scale printing equipment. For example, a manufacturer of flatbed screen printing machines uses a 1.5KW frequency converter from Shanghai Delta Electronics; Huainan Xinsheng Company uses a 220V frequency converter from Shanghai Jiachuan for its double-head stapler; a folding machine manufacturer in Xinshao, Hunan uses a 1.5KW LS600 frequency converter; and three other manufacturers of straight-line wrapping machines and oval wrapping machines use frequency converters from Wuxi Taian Technology, HOLIP, and TVERTER, respectively.