I. Overview:
The NOEGR1400/2 large-roll hydraulic transmission dyeing machine, manufactured by the Portuguese company NOEGR, is valued at over one million yuan per unit. It is suitable for small-batch, multi-variety flat-width fabrics undergoing processes such as sizing, dyeing, washing, pattern making, and stripping under normal temperature and pressure. It is an indispensable piece of technical equipment for large-scale textile printing and dyeing enterprises . Many domestic printing and dyeing companies own this model. The core technology of this machine is maintaining constant linear speed and fabric tension of the winding rollers during operation while handling a large fabric capacity (800-6000 meters). The electrical automatic control computer originally used a Z8 single-chip microcomputer controller from the Italian company Termoelectronica (the manufacturer no longer produces it); it integrated control, display, and parameter setting; it was difficult to procure domestically.
II. Reasons for the renovation:
With increasing service life , the humid production environment in the dyeing and printing workshop causes the main control computer to experience aging connectors, poor contact, severe corrosion of circuit boards, easy loss of parameters, and system crashes. This easily leads to abnormal control actions, signal distortion , and affects the normal operation (or damages) of speed and tension control devices. On the other hand , the mechanical connection components (mechanical seals) of the synchronous closed-loop speed feedback sensor in the original design are prone to wear due to contact with the dye liquor, resulting in easy damage (even causing sensor damage) , which in turn affects the stability of linear speed and tension, causing color differences in the fabric. Furthermore, the system requires numerous input parameters , has cumbersome operating procedures , requires significant equipment maintenance , and spare computer parts are unavailable domestically, impacting production progress. It is difficult to meet the needs of modern industrial production.
In response to the aforementioned unfavorable factors, we proposed a corresponding transformation plan, replacing the original Z8 microcontroller-based dedicated control computer with a more advanced technology platform—the general-purpose programmable logic controller (PLC) series and human-machine interface (touch screen) products.
III. System Composition:
The hydraulic transmission system of this equipment (the hydraulic components are from Bosch, Germany) is advanced in design , leading the domestic market for large-roll dyeing machines and remaining largely intact. Therefore, the improvement principle is to not modify the main control circuit of the hydraulic transmission , but only to modify the original electrical computer automatic control system. The original electrical components will be used, and the design and drawings will be rewritten , with corresponding application programs developed according to the characteristics of the roll dyeing process. A general-purpose PLC and touch screen system will be used to systematically replace the human-machine interface and automatic control of this equipment. The overall control system structure is shown in Figure 1.
Control commands are centrally operated via the system's touchscreen. The system outputs control signals based on operator commands and calculates the required speed and tension values based on closed-loop data. It then controls the flow rate of the hydraulic valves, driving the rotation of the hydraulic motor to achieve constant linear speeds of the A and B winding rollers under constant tension. This completes the dyeing process, including multiple transfer dyeing stages in the dyeing vat.
In the design of the core application, the winding roller linear speed is used as the "primary" control variable , and tension is used as the "secondary" control variable. These two variables are controlled alternately, and each control employs an online rule-based self-adjusting PID control function. This fundamentally solves the problem of "constant linear speed" and "constant tension" in the entire system, greatly improving the reliability and stability of system operation. Furthermore, it eliminates the need for a synchronous closed-loop speed feedback sensor ; the closed-loop feedback is calculated by the application program based on the collected data.
The flowchart is as follows :
IV. Main Technical Features:
The required application program has been modified and improved online according to the process operation requirements, which has made the machine's linear speed and tension more constant, improved the machine's automation level, made its performance more stable and reliable, enhanced its functions, made its operation simple and intuitive, reduced labor intensity, and greatly improved production efficiency.
1. Applicable to applications using hydraulic, AC frequency conversion, and DC motor transmission methods.
2. Reduced operation steps and no need to input parameters enable operators to quickly become familiar with and proficient in operating the machine.
3. It can be improved or practical functions can be added in real time according to process requirements, and spare parts are easy to purchase.
4. The diameter of the winding roller changes dynamically , while the linear speed of the main and auxiliary winding rollers and the fabric tension remain constant.
5. The system has a high degree of integration, and its electrical structure is simple, intuitive, and easy to inspect, thus reducing the failure rate.
V. Main Functions:
1. The entire interface is in Chinese with a touch screen, and it is easy to operate with a user-friendly and intuitive interface.
2. Select between manual and automatic machine modes.
3. Single-button control for direction selection.
4. The winding amount of rollers A and B is collected and displayed in real time by sensors on the winding rollers.
5. Manual/automatic reversing function.
6. Speed setting range: 0-150 meters.
7. "Swing" function --- operates at the end of the fabric transfer stage between rollers A and B, and is used in the process preparation stage.
8. Real-time recording and display function of total fabric transfer path.
9. Indirect and direct dual constant temperature control system for dyeing tank.
10. Fast or slow feeding options.
11. Choose the amount of ingredients to add.
12. Liquid level indicator in dyeing tank.
13. Zeroing function for winding amount of A and B rollers.
14. The initial fabric feed on the winding roller is 5 meters.
15. Sampling function: Automatically stops the machine to sample based on the settings of sampling points on rollers A and B.
16. "Passage Count Setting" function --- When the set value for the number of passes required for fabric transfer on rollers A and B in each process is reached, it automatically enters the "swing" state.
17. The running time for each stage is displayed in real time , making it convenient to determine the dyeing time.
18. The given speed and actual speed are displayed in real time without needing to be switched.
19. Real-time date and clock display function.
20. All function control buttons are centrally located on the touchscreen for easy operation.
VI. Economic Evaluation of the Scheme Application:
Anhui Huawan Carbon Fiber (Group) Co. , Ltd. purchased four of these machines in 1996. Computer malfunctions frequently occurred during dyeing production , significantly impacting the smooth completion of the dyeing process . Statistics showed that annual maintenance costs and product downgrade losses amounted to approximately 50,000 yuan . After an upgrade in 2003, the computer malfunction rate was zero. Production volume, quality, and efficiency improved significantly , and the upgrade was well-received.
Practice has proven that after two years of use, the touch screen and PLC control system has demonstrated stable hardware and software operation , reliable overall machine operation, and a highly successful transformation plan. Production quality has stabilized, output has increased, labor intensity and production costs have significantly decreased , resulting in substantial economic benefits. The excellent performance of the touch screen and PLC control system makes it suitable for a wide range of applications in industrial electrical automation.
VII. Technology Promotion:
Since industrialized countries successively developed PLCs, and with the widespread application of microcomputer technology , the functions of PLCs have been continuously enhanced , and their applications have become increasingly widespread. It represents a leap forward in modern control technology, possessing characteristics such as stable performance, good versatility, small size, powerful functions, ease of use, easy modification of control processes, and energy saving. Furthermore, its integration with information technology, particularly in system monitoring and management, has led to its increasing application in modern industrial automatic control systems, making it an inevitable development direction for the upgrading and renewal of automation technology in today's manufacturing enterprises.
