Abstract: Based on an introduction to the background of technological automation progress in the rubber industry and the principle of vulcanization process, this paper discusses in detail the synchronous frequency conversion drive design technology based on Delta electromechanical products. Keywords: Rubber vulcanization, frequency converter, synchronous drive 1 Introduction The development of high technologies such as information technology and opto-mechatronics has powerfully promoted the technological progress of the rubber industry. Utilizing high technology to transform the traditional rubber industry and developing production technology towards high technology is the only way to build a strong rubber industry. At present, the rubber industry is still an industry with a lot of manual operation, especially for products with many parts such as tires and rubber shoes. The molding process alone involves more than a dozen steps, resulting in high labor intensity and low production efficiency, which seriously affects the development of the rubber industry. Developed industrial countries have focused on the molding process of rubber products and have made significant progress in automated production through computer technology, opto-mechatronics technology, and robotics. 2 Continuous Vulcanization Production Process Control 2.1 Vulcanization Molding Vulcanization molding is an important process in rubber processing. To improve the performance of rubber products, a series of processing steps are required for raw rubber in production. Under certain conditions, the raw rubber in the rubber compound reacts chemically with the vulcanizing agent, causing it to crosslink from linear macromolecules into three-dimensional network macromolecules, thus giving the rubber compound excellent properties such as high strength, high elasticity, high wear resistance, and corrosion resistance. This process is called rubber vulcanization. The vulcanization process is generally divided into four stages: induction, pre-vulcanization, positive vulcanization, and over-vulcanization. To achieve this reaction, external energy must be applied to reach a certain vulcanization temperature, and then the rubber is kept warm within the vulcanization temperature range to complete the entire vulcanization reaction. 2.2 Continuous vulcanization process control (1) Microwave rubber vulcanization equipment and production process. The basic process flow of microwave rubber vulcanization for rubber products with skeleton is as follows: the molded product extruded from the extruder is conveyed by a conveyor belt or roller conveyor and enters the microwave vulcanization device. Here, the rubber is rapidly heated to the vulcanization temperature, and then enters the hot air tank for secondary vulcanization to complete the foaming and vulcanization process of the product. The microwave rubber vulcanization production line consists of a wire feeding device, an extruder, a high-temperature shaping device, a microwave vulcanization device, a hot air vulcanization device, a cooling section, a traction machine, a cutting machine, a punching machine, etc. (2) Process transmission control. After the wire feeding device and the wire feeding tension control are completed, the wire passes through the pre-forming roller frame and is heated. The rubber material extruded by the extruder is covered with a jacket. The wire covered with the rubber jacket enters the main speed traction device of the production line. After high-temperature vulcanization, the production speed per minute is controlled by the frequency converter. Then, it enters the post-processing stage through the auxiliary traction of the crawler. In the core metal breaking and forming device, the tension is detected by the tension frame as tension feedback. The speed is given by the main speed. The wire is fed at a uniform speed and constant tension. After being controlled by the meter counter, it is cut into shape. On the whole production line, the main traction and auxiliary traction control system works in the speed mode: including high-temperature treatment, microwave vulcanization, and post-heating speed series synchronization; and it is required that each level can be finely adjusted and the subsequent level can be synchronously adjusted. The steel strip feeding and forming control system operates in constant torque mode; torque fluctuations caused by speed mode are controlled by the torque control system, working together to ensure constant speed and tension. 3. Variable Frequency Drive Synchronous Drive System 3.1 Synchronous Drive System Principle Design On the entire production line, the main traction and auxiliary traction control systems operate in speed mode: including high-temperature treatment, microwave vulcanization, and post-heating speed series synchronization; and each stage is required to be fine-tuned and the subsequent stage to be synchronously adjusted. The solution to the speed synchronization problem is shown in Figure 1. Configuration Design: 3 x 5.7-inch 1711STN HITECH touchscreens; 1 x DVP12SA Delta PLC; 4 x VFD007B43A variable frequency drives. This configuration only involves the synchronization of four variable frequency drives on the production line. The entire production line is controlled by three HMIs and four frequency converters. The four frequency converters control the frequency of the assembly line, which is divided into four control segments. The project mainly utilizes the convenience of Delta's communication technology to read the frequency of the frequency converters anytime, anywhere via communication. If a change in the frequency of one frequency converter is detected, the subsequent frequency converters will adjust accordingly based on a certain ratio to handle the synchronization of the four speed segments and control the tension. The three HMIs form a master-slave configuration and are installed in each work segment. The interface of each HMI is made completely identical, and operation can be performed on any touch screen for the convenience of the operator. Previously, the customer used the HMI UP/DOWN method for fine-tuning, but the customer found it inconvenient. They also used a Delta four-channel synchronous controller. However, the customer's current requirement is to set the master frequency and ratio relationship on the HMI. However, the HMI distributor chose HITECH HMIs, which only have two communication ports, and both of these ports were already occupied, so the synchronous controller could not be used. [align=center] Figure 1 Solution to the speed synchronization problem[/align] 3.2 Synchronization control requirements analysis of four frequency converters. When the frequency of one frequency converter is changed (by analog quantity, or by setting the main frequency or proportional quantity), the frequency of the subsequent frequency converters will be automatically corrected to ensure synchronization. Moreover, when the frequency of two or more frequency converters is fine-tuned by analog quantity or by changing the proportional or main speed through human-machine interface, the first one shall be used as the reference, and the frequency value modification of the subsequent frequency converters must be masked. For example, if two operators on site simultaneously modify the analog quantity of the second and third frequency converters to fine-tune the frequency, the frequency modification value shall be based on the second one. 3.3 Design of assembly line transmission relationship (1) Frequency converter frequency setting source: frequency converter main frequency (communication setting) + 0-10V analog quantity superposition. (2) Synchronization relationship of frequency converters: the frequency value of the first frequency converter = the main speed setting (by human-machine interface setting) + the analog auxiliary frequency setting of the first frequency converter (by analog quantity setting). (3) Second frequency value = First frequency value * Proportion 1 (set via HMI) + Second analog auxiliary frequency setting (set via analog quantity). (4) Third frequency value = Second frequency value * Proportion 2 (set via HMI) + Third analog auxiliary frequency setting (set via analog quantity). (5) Fourth frequency value = Third frequency value * Proportion 3 (set via HMI) + Fourth analog auxiliary frequency setting (set via analog quantity). 3.4 Programming difficulties The frequency value is the main frequency and analog auxiliary frequency setting. It is unknown when the analog auxiliary frequency will change on site. Therefore, when writing the program, the frequency must be read every moment to understand the frequency value change of the frequency converter on site. Moreover, after the frequency is read, it is necessary to calculate according to the proportion based on the frequency change. The calculated frequency value is automatically written to the corresponding frequency converter via communication. Because the frequency is read every moment and the frequency is given from two sources, the difficulty lies in when to give the written comparison value to the register and then use this frequency value to compare with the read frequency as a reference value. Originally, we wanted to use A/D and D/A analog signal interfaces. Although this would make programming simpler, the production line was too long (50 to 60 meters long), and the analog signals for fine-tuning had to be close to each workstation. The wiring was difficult, and the analog signals would suffer from significant attenuation and interference on such a long line. Communication would be a better option. Therefore, we adopted a communication-only approach to meet the customer's synchronization requirements. This made the programming more complex, especially regarding when to provide the comparison value and how to shield the frequency changes of the subsequent units. 3.5 Programming Ideas (1) When the analog signal changes. After reading the frequencies of all frequency converters once (d190-d197), the frequency changes (when the analog signal changes), and this frequency change lasts for two seconds. Then, set m10 and trigger m1-m3 to calculate the corresponding frequency (the frequency value is placed in d2000-d2007). Then, start writing the frequency. After writing, time 100 milliseconds and then start reading the frequency again. After reading once, trigger m16 to record the value (D590-d597), and then start reading the frequency again in a cycle. (2) When the proportional value changes (m100 m101 m102 m103), firstly, when the main speed is modified (m100 is set), set m10, write the frequency of the first inverter, after writing, set m17 after 100ms, then read the frequency once, trigger m18, then according to the actual frequency read from the first inverter, according to the corresponding proportional value (d550-d555), trigger m10 again, write the frequency again, after writing, after 100ms, read the frequency again, after reading the frequency, trigger m16 and record the value. Secondly, when modifying the ratio (m101, m102, m103 set), the corresponding frequency is calculated based on the read value according to the ratio (frequency values ​​are placed in d2000-d2007). Then, the frequency is written. After writing, a timer is set for 100 milliseconds, and then the frequency is read again. After reading once, m16 is triggered, and the value is recorded (D590-d597). Then, the frequency reading cycle is repeated. Ratio values: D550, d552, d554; Frequency values: D2000, d2002, D2004, d2006. 3.6 Problems Encountered and Solutions During Debugging The main problem encountered during debugging was in the communication read/write process. Because multiple inverter parameters were read and written simultaneously, and all read/write operations were automatic, variables were used to switch station numbers during program writing to minimize the program size. Due to a problem with Delta's underlying program, occasional data misalignment occurred. However, in previous environments with low communication requirements, these momentary data misalignments had no impact on the equipment, and they were infrequent, usually occurring only every few hours and immediately resetting. In these less demanding environments, they were generally not noticed. This time, because several inverters were continuously being read, and after reading, a frequency change was detected through comparison, and the frequency was immediately calculated and automatically written to the other inverters to maintain synchronization, read errors were unacceptable; otherwise, the inverters would immediately overshoot and become inoperable. Therefore, after continuous testing, it was found that during communication read/write operations, the program must include the condition of storing the distinguished data after reading it from the communication (both D1070 and D1071 must be used). 4. Conclusion Synchronous drive is a fundamental technology of mechanized assembly lines. Since the advent of frequency converter drives, synchronous drive issues have increasingly become typical frequency converter application technologies. This project, through commissioning, met the automation requirements of key rubber processing processes, demonstrating Delta Electronics' engineering capabilities in promoting technological progress in the rubber industry.