Application of ME Series Inverters in Low-Temperature One-Step Rubber Compounding Systems
2017-02-24
Abstract: This paper introduces the ME series frequency converters used in conjunction with a low-temperature single-stage rubber compounding system, enabling automation of the compounding process and enhancing production efficiency. It also elaborates on the process characteristics of low-temperature single-stage rubber compounding. Furthermore, it describes the control methods and speed-regulation features of the ME series frequency converters during the rubber compounding process.
Keywords: Low-temperature one-step rubber processing, ME series frequency converters, open-loop vector control
Overview
The rubber compounding process is a major energy consumer in the entire tire manufacturing process. Improving the efficiency of rubber compounding and reducing its energy consumption have long been important research topics in the industry. The low-temperature one-step rubber compounding technology replaces the traditional multi-stage mixing process with a single-stage mixing approach. This technology enables continuous mixing production, allowing for the direct acquisition of finished rubber compound in one step, with a high degree of automation and significantly improved production efficiency. It also reduces the number of operators required and ensures greater stability in rubber compound quality. Consequently, the low-temperature one-step rubber compounding system places extremely high demands on automated control and drive systems.
A large tire manufacturer in Guangdong has commissioned two low-temperature one-step rubber compounding systems. The ME-series dedicated frequency converters from STEP have been selected as the drive frequency converters for these two systems, thanks to their specialization, stability, and convenient communication features.
Process Introduction
The low-temperature one-step rubber compounding process involves first feeding the rubber compound discharged from the internal mixer into the No. 0 compounding unit, where it undergoes brief mixing to cool down and form sheets, making it easier to transport. The compound is then automatically queued via a programmed sequence and conveyed to one of the units numbered 1 through 6. In this specific unit, the compound completes cooling, further mixing, sulfurization, refining, and finally is discharged onto an open-roll mill for sheet formation. Lastly, the rubber sheets are cooled and stacked on a dedicated cooling line, thereby completing the entire compounding process for one batch of rubber. Throughout this process, after being discharged from the internal mixer, the rubber compound does not require any intermediate storage or waiting periods—instead, it directly proceeds to the open-roll mill for final compounding. This system employs six sulfurizing compounding units, and by precisely coordinating the operational cycles of each unit with those of the internal mixer, it ensures maximum production capacity.
Product Configuration
3.1 System Drive Diagram
Figure 1: Drive Diagram of the Low-Temperature One-Step Rubber Processing System
This project utilizes 11 ME-series variable-frequency drives in its low-temperature one-step rubber compounding system: two for the internal mixer and nine for the open mill. The system’s control bus adopts the Profinet communication protocol, which offers higher implementation flexibility. As an Ethernet-based bus protocol, Profinet can simultaneously transmit TCP or IT data, making factory automation easier to achieve.
3.2 Features of the Open Mill Driven by the ME500 Low-Voltage Variable Frequency Drive
Figure 2: Block Diagram of Open-Loop Vector Control Principle
1. The ME500 low-voltage frequency converter employs advanced motor model control and utilizes open-loop vector control on-site, enabling rapid response to sudden load changes and meeting the load-drive requirements of open-mill machines.
2. Precise rotor flux-oriented control capability ensures rapid response and stable operation even under sudden changes in load torque at 0 Hz.
3.0.1s full-load acceleration, fast torque response, minimal speed overshoot—boosting production efficiency.
4. Communication bus control—more convenient to operate and with stronger anti-interference capability.
Summary
The ME-series dedicated frequency converters have been successfully applied to low-temperature single-step rubber compounding systems. The entire compounding system achieves energy savings of approximately 10% to 15% compared to traditional DC speed-regulating systems, providing a new direction for factories to conserve energy and reduce emissions.
Figure 3-4: On-site commissioning of the inverter cabinet
Figure 5-6: Process Diagram of the Series-Type Internal Mixer and Single-Stage Open Mill (No. 0, No. 7)
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