Internal Mixer Research Report

Introduction

In the field of polymer material processing, the internal mixer, as a key piece of equipment, is widely used in the plasticating and mixing processes of materials such as rubber and plastics. Its efficient mixing performance and controllable process conditions make the internal mixer an important tool for improving material processing quality and production efficiency. This article aims to explore the working principle, structural characteristics, operation methods, and applications of internal mixers in polymer material processing, in order to provide valuable references for researchers and practitioners in related fields.

Theoretical Basis and Conceptual Framework of Internal Mixers

An internal mixer is a machine that plasticates and mixes polymer materials intermittently under adjustable temperature and pressure in a closed state through a pair of rotors with specific shapes that rotate relative to each other. The working principle of the internal mixer is mainly based on the shearing, tearing, and squeezing actions of the rotors on the material, as well as the repeated circulation and mixing process of the material in the mixing chamber.

Development History of Internal Mixers

The history of internal mixers can be traced back to the early 20th century, when engineers began to research and create prototypes of internal mixers. After continuous improvement and refinement, in 1916, British engineer Banbury invented the "Banbury Mixer" with an upper ram and a drop-down discharge door. Since then, internal mixers have been widely used in the mixing and processing of rubber and plastics. Subsequently, a series of improvements were made to the feeding, discharging, cooling, and pressing devices of the internal mixer, making its operation safer and more efficient, and significantly improving product quality and the working environment.

Structural Characteristics of Internal Mixers

Internal mixers are mainly composed of a mixing chamber, rotors, upper ram, lower ram, temperature measurement system, heating and cooling system, exhaust system, safety device, discharge device, and recording device. Among them, the rotor is the core component of the internal mixer, and its surface usually has spiral protrusions used to exert strong shearing and squeezing actions on the material. The shape and size of the mixing chamber can be designed according to the material properties and process requirements to meet the mixing needs of different materials.

Working Principle of Internal Mixers

During the operation of the internal mixer, after the material is added from the feed port, it first falls into the upper part of the two relatively rotating rotors. Under the pressure and frictional force of the upper ram, the material is brought into the gap between the two rotors and subjected to strong shearing and squeezing actions. Then, the material is separated by the protrusions of the lower ram, and it passes through the gap between the rotor surface and the mixing chamber wall along with the rotation of the rotor, again undergoing strong mechanical shearing and kneading actions. This cycle is repeated until the material reaches the required mixing degree.

Previous Research Findings and Current Research Gaps

Previous research on internal mixers has mainly focused on the following aspects: rotor structural optimization, mixing mechanism exploration, process parameter optimization, and automated control of internal mixers. These studies have provided valuable experience and theoretical basis for the design, manufacturing, and use of internal mixers.

However, there are still some gaps or unresolved issues in current research. For example, how to further improve the mixing efficiency and uniformity of internal mixers? How to optimize process parameters to reduce energy consumption and production costs? How to achieve intelligent control and remote monitoring of internal mixers? These issues need to be addressed to promote the continuous progress and wide application of internal mixer technology.

Research Design and Methods

This study uses a combination of experimental research and theoretical analysis to conduct an in-depth exploration of the working performance, structural characteristics, and application effects of internal mixers.

Experimental Design

The experiment uses different types of internal mixers to conduct co-blending experiments of polypropylene and polyethylene. By adjusting process parameters (such as temperature, speed, and filling factor), the mixing process, torque changes, temperature curves, and pressure curves of the material are observed and recorded. At the same time, the mixed material is subjected to performance testing to evaluate the mixing effect and product quality of the internal mixer.

Data Collection and Analysis

Experimental data is mainly collected through sensors and recording devices built into the internal mixer, including torque sensors, temperature sensors, and pressure sensors. The collected data is organized and analyzed using professional software to extract key information and patterns. At the same time, combined with theoretical analysis, the experimental results are explained and verified.

Research Results and Analysis

Torque Changes and Mixing Effects

The experimental results show that as the speed of the internal mixer increases, the torque value gradually increases, indicating that the shearing and squeezing actions on the material in the mixing chamber are enhanced. At the same time, the change in torque value also reflects the change in material viscosity, which can be used to judge the mixing degree and uniformity of the material. By comparing the torque curves and mixing effects under different speeds, it is found that appropriately increasing the speed is beneficial to improving mixing efficiency and uniformity.

Temperature Curves and Energy Consumption Analysis

The temperature curve shows the change in material temperature in the mixing chamber. The experimental results show that as the mixing time increases, the material temperature gradually increases. By adjusting the parameters of the heating and cooling system, the change range of the material temperature can be controlled to meet the mixing requirements of different materials. At the same time, energy consumption analysis shows that appropriately reducing the speed and filling factor can reduce energy consumption and production costs.

Pressure Curves and Material Flow

The pressure curve reflects the change in material pressure in the mixing chamber. The experimental results show that the pressure on the material in the mixing chamber increases with the increase in speed and filling factor. By optimizing the structure and process parameters of the internal mixer, the flowability and mixing effect of the material can be improved. At the same time, the analysis of the pressure curve also helps to understand the stress and deformation of the material during the mixing process.

Research Conclusions and Outlook

Research Conclusions

This study uses a combination of experimental research and theoretical analysis to conduct an in-depth exploration of the working performance, structural characteristics, and application effects of internal mixers. The research results show:

1. The torque change of the internal mixer is closely related to the mixing effect, and appropriately increasing the speed is beneficial to improving mixing efficiency and uniformity.
2. Temperature curves and energy consumption analysis provide important basis for optimizing process parameters, and appropriately reducing the speed and filling factor can reduce energy consumption and production costs.
3. The pressure curve reflects the stress and deformation of the material during the mixing process, and has guiding significance for optimizing the structure and process parameters of the internal mixer.

Future Research Directions

Based on the results of this study and the gaps in current research, future studies can further explore the following questions:

1. How can the rotor structure and process parameters of the intensive mixer be further optimized to improve mixing efficiency and uniformity?
2. How can intelligent control and remote monitoring of the intensive mixer be achieved to improve production efficiency and safety?
3. How can the intensive mixer be combined with other processing equipment to form a complete polymer material processing production line to achieve automated and continuous production?

These questions will be important directions for future research, and are expected to promote the continuous progress and wide application of intensive mixer technology. At the same time, Wuxi Dingyu Rubber and Plastics Machinery Co., Ltd. also looks forward to more researchers and practitioners participating in the research and application of intensive mixer technology, jointly promoting the development and innovation of the polymer materials processing industry.