Probe into the intelligent control of multi cylind

Discussion on the intelligent control of multi cylinder and electric heating synchronization of wide width flat plate vulcanizer

according to the market requirements, we have developed and designed a series of units of wide width flat plate vulcanizer, whose host requirements are 3.2 ~ it can completely replace glass fiber composites and improve the comprehensive performance of interior trim panels; In addition, it has a width of 6.4 meters, adopts detachable prestressed frame, multi cylinder upper and lower pressing, low-level material saving, ceramic electric heating, single high-pressure hydraulic station, middle cutting and framing, single/double-layer design, two-way wiring, etc. The unit is positioned to equip users of high-strength steel rope conveyor belts and sheet coils in the international, domestic and renewable rubber utilization markets. In order to protect intellectual property rights, the key technology of this series of units is proposed to apply for invention patents. One of the key points of this research and development project is that the multi cylinder synchronous and electrothermal synchronous intelligence is surrounded by a rim made of solid polymer

1. The demand for Synchronous Intelligent Control

generally, the lower up pressure or upper down pressure of column and frame flat belt vulcanizers adopts the way of step-by-step oil supply large-diameter hydraulic cylinder. In these ways, due to the pressure of 1.5 ~ 3Mpa (4MPa from foreign manufacturers) on the vulcanization green belt during the vulcanization process, the hydraulic cylinder and the machine body are huge, the total amount of consumables is amazing, and the cost remains high. Different from the previous design, this research and development design adopts the anti traditional multi cylinder upper and lower pressure, while the multi cylinder hollow stroke part adopts the gas-liquid compensation, the work pressure maintaining part adopts the thin single acting high-pressure jack, and the crotch opening return journey adopts the reverse same type high-pressure Jack. In the process of research and development, although mechanical synchronization, forced intermittent oil supply by a single high-pressure pump station and the control of electrohydraulic servo valves of the same model are designed, and all electrohydraulic servo valves have the same basic input signal to maintain basic synchronization, the synchronization error is eliminated by adjusting the input signal of electrohydraulic servo valve to control the oil input. However, due to the requirements of semi closed-loop servo control, we have attached a magnetostatic grating cylinder stroke detector to each cylinder. This is a new type of cylinder external position sensor, which has many functions, such as position display, closed-loop control and communication conversion. This kind of electro-hydraulic position control needs to consider intelligent control

secondly, different from the double channel hot plate heating method of steam superheated water, electric heating oil or electric heating tube plus cooling water, we use CO fired ceramic electrothermal components to heat the hot plate, which uses high thermal conductivity ceramics - alumina ceramics as the matrix, and heat-resistant refractory metal as the internal electrode to form a heating circuit. Through a series of special processes, two pieces of alumina green ceramics are co fired (sheet elements), which has the following advantages: 1) simple structure; 2) Rapid temperature rise; 3) High power density; 4) The heating temperature is higher than 400 ℃; 5) High thermal efficiency; 6) Heating evenly; 7) No open fire, safe to use; 8) It can realize complex planar heating; 9) The heating circuit is isolated from the air, and the components are resistant to acid, alkali and other corrosive substances, with long service life; 10) The component itself and its production process meet the requirements of environmental protection (RoHS) and have international SGS certification. The use of ceramic electric heating elements has obvious effects on material saving, water saving and consumption reduction. It can accurately control the temperature of the heating area, stabilize the vulcanization effect, and even have flexibility for the coated vulcanization flat belt of different materials. Similarly, this kind of electric heating control also needs to consider the intelligent control

in the vulcanization process, vulcanization pressure and temperature are extremely important parameters. Due to different uses of products, vulcanization materials and formulas are different, and vulcanization process parameters are also variable. Even minor changes need to be considered prospectively and comprehensively in the R & D and design of equipment manufacturers. The integration thinking of the above two kinds of intelligent control is the cause of this paper

2. Multi cylinder synchronous control

in the multi cylinder configuration, the travel position of the reference cylinder is used to calibrate the zero point of the position sensor of the remaining pressurized cylinders, while the pressure equalizing rib of the dynamic/fixed heat plate adopts the FEA optimization design, and the mechanical synchronization, manufacturing and use errors adopt the traditional lead pressing method to compensate the cold and hot static value, so as to determine the original zero point of the machinery. However, when the thickness deviation of the product exceeds the standard, it is necessary to check the origin again

the synchronous control process is as follows: the synchronous error of the position of each non reference cylinder and the position of the reference cylinder in the magnetostatic grating cylinder stroke detection is collected to PLC or computer through a/d conversion, and processed under the software algorithm with the advantages of preset control intelligence, including the increase of sag under high power transmission, and then the digital control quantity is output, and then converted into analog voltage signal by d/a, By adjusting the input signal of the electro-hydraulic servo valve, the oil inlet of the differential oil cylinder is controlled to eliminate the synchronization error, and the electro-hydraulic subsystem is controlled to drive each oil cylinder to realize the synchronous movement. When the error reaches the tolerance balance value, the pressurization system enters the pressure maintaining state, and the high-pressure pump station stops. Since the manufacturing accuracy of the seal and the oil cylinder is unified, it is certain that the error caused by the subsequent leakage is basically controlled within the same tolerance range

3. Synchronous control of electric heating

as the co fired ceramic electric heating components may cause regional temperature difference on the area of a single piece and differential temperature difference between pieces in the manufacturing process, the design adopts clamped aluminum soaking plate, and the temperature measurement adopts drilling holes on the back surface of the hot plate opposite to each Co fired ceramic electric heating component to place several thermocouples, and the co fired ceramic electric heating components also control the power supply respectively. The calibration temperature measurement method is the same as the traditional method, and the single reference temperature is directly set in HMI

the process of temperature synchronous control is as follows: the temperature error of each co fired ceramic electrothermal component is collected to PLC or computer through a/d conversion, processed under the preset intelligent software algorithm, and then the switching value signal of the relative co fired ceramic electrothermal component is output. Through the on-off signal, the thyristor is controlled to turn on and generate heat to realize synchronous temperature control. When the temperature is close to the required temperature, the power is cut off and the temperature is gradually supplemented. Similar duty cycle methods ensure that the temperature fluctuation is limited to the range of tolerance equilibrium value, so cooling water is not needed, but the local anti vulcanization water-cooling device at the end is still needed, because the steel hot plate will be homogenized with time, which may cause scorching of the joint lap and sulfur, affecting the flat strip quality

4. The most critical part of synchronous control system is the selection and optimization of intelligent control scheme. Different control schemes have their own characteristics, and they can achieve the expected purpose through some adjustment methods and principles. After comparison and analysis, Fuzzy-PID Compound Control is adopted for the above synchronization

fuzzy control does not establish a mathematical model and has good robustness, but its control action is not delicate and its steady-state accuracy is not good. Due to the use of a PLC or IPC for control, it is necessary to take into account the requirements of control temperature and control position. Fuzzy control can be used for temperature synchronization control here. At the same time, fuzzy control can also be used for multi cylinder position synchronization before the end of the stroke is close to the end, and PID control is better when it is close to the end to stabilize the error, Therefore, we can integrate the advantages of the above two controls and introduce Fuzzy-PID Compound Control to improve the comprehensive performance of the control system

the scheme of combining fuzzy control and PID control is: set a domain value, and when the error is outside the domain value, use fuzzy control to obtain better transient performance; When the error falls within the domain value, PID control is used to obtain better steady-state performance. The control strategy combining fuzzy control and PID control is fuzzy PID compound control

fuzzy PID composite control chart

in the specific control program, the same control intelligent module software algorithm is used, but relative to multi cylinder synchronization and temperature synchronization, the error value of a/d conversion is converted into equal order error data, and the output results are d/a and switching values, respectively. The two synchronization items are controlled respectively. In actual operation, these two kinds of control generally do not occur at the same time with the vulcanization process steps, Manual intervention or polling can be avoided. At the same time, the sum of data collection volume and points in Germany's wacksdorf technology capability Center (TCC) has different requirements for the development and industrialization of new syringes, and the coherent advantages of a/d conversion module, so segmented control is also imperative

5. Conclusion

flat belt and plate vulcanizer is a mature equipment product with a long history of production. The difference between domestic models and foreign models lies in the level of control and stability. The positioning of R & D of new machines is to narrow the gap. Therefore, when we develop a wide flat belt vulcanizer, we have made an integrated discussion on its key technology, multi cylinder synchronization and electrothermal synchronization intelligent Fuzzy-PID composite control. Its method is an innovative attempt. At the same time, it also provides a reference idea for R & D technicians in the same industry. Its purpose is to jointly promote the progress of China's rubber machine equipment manufacturing level towards the world. (end)