Analysis of the Application of Temperature Control System in Vulcanizing Machine
The temperature control system is a core component of the vulcanizing machine, directly affecting the vulcanization quality of rubber, production efficiency and equipment service life. It ensures the stability and consistency of the vulcanization process by precisely controlling the heating temperature, optimizing the heat transfer process and providing real-time feedback regulation. The following is an analysis of the functions, key technologies, application scenarios and optimization directions of the temperature control system.
First, the core function of the temperature control system
Precise temperature control
Objective: To stabilize the vulcanization temperature within ±1℃ of the process requirements (for example, natural rubber is usually 145-155℃).
Implementation method: The heating power is dynamically adjusted through the PID (proportional-integral-Derivative) algorithm to avoid overmodulation or undermodulation. For example, when the temperature approaches the set value, the PID controller will gradually reduce the heating power to prevent temperature fluctuations.
Multi-segment temperature programming
Segmented vulcanization process: Supports setting different temperature curves according to the vulcanization stage. For example, the pre-vulcanization stage (low temperature for a short time), the main vulcanization stage (high temperature for a long time), and the cooling stage (cooling and setting).
Application scenario: In the vulcanization of thick products, internal stress is reduced by stepwise heating to avoid delamination or bubbles.
Temperature uniformity guarantee
Thermal balance technology: By optimizing the structure of the heating plate (such as zonal heating and the design of the flow guide groove) and the material of the insulation layer, it is ensured that the surface temperature difference of the heating plate is ≤2℃.
Case: In the vulcanization of large conveyor belts, if the temperature difference between the center and the edge of the heating plate is too large, it will cause local under-vulcanization or over-vulcanization of the joint.
Second, key technologies of the temperature control system
Sensors and Data Acquisition
Thermocouple/thermal resistance: Used for real-time monitoring of the temperature inside heating plates, molds and rubber. For instance, the K-type thermocouple has a fast response speed and is suitable for dynamic temperature monitoring.
Infrared temperature measurement: Non-contact measurement of rubber surface temperature, avoiding interference to the vulcanization process caused by sensor contact.
Heating elements and drives
Electric heating tubes/ceramic heating plates: Control the heating power by adjusting the supply voltage or current. For instance, solid-state relays (SSR) are adopted to achieve contactless switches and extend their lifespan.
Heat transfer oil/steam circulation: In large vulcanizing machines, uniform heating is achieved by pumping the heat medium, and the temperature control system needs to coordinate the control of the medium temperature and flow rate.
Intelligent control algorithm
Adaptive PID: Dynamically adjust the PID parameters according to the vulcanization process to adapt to different rubber types and product thicknesses.
Fuzzy control: In systems with significant temperature lag (such as steam heating), it responds rapidly to temperature changes through fuzzy logic.
Third, the application scenarios of the temperature control system
Vulcanization of conveyor belts
Requirement: Ensure the bonding strength between the rubber and the steel wire rope and the canvas layer.
Key points of temperature control
When vulcanizing the joint, the temperature should be evenly diffused from the center to the edge to avoid local overheating causing bonding failure.
During the cooling stage, the temperature should be reduced slowly (≤5℃/min) to prevent thermal stress cracking.
Tire vulcanization
Requirement: Ensure the consistency of vulcanization on the tread, sidewall and bead.
Key points of temperature control
When using a dual-mode vulcanizing machine, the temperatures of the upper and lower molds need to be independently controlled to compensate for the difference in thermal inertia of the molds.
Monitor the tread temperature through infrared sensors and adjust the steam pressure or electric heating power in real time.
Vulcanization of seals
Requirement: Control the hardness and elasticity of rubber.
Key points of temperature control
Small-sized products have a short vulcanization time (usually ≤5 minutes), and the temperature control system needs to have a rapid response capability.
Reduce the temperature fluctuation at the initial stage of vulcanization by preheating the mold.
Fourth, Common problems and solutions of Temperature control systems
Temperature overshoot
Phenomenon: When heated, the temperature exceeds the set value, causing the rubber to be over-sulfurized.
Reason: The PID parameters are unreasonable and the power of the heating element is too high.
Solution: Optimize the PID parameters (such as reducing the proportional gain Kp), or adopt a segmented heating strategy.
Temperature lag
Phenomenon: The temperature change lags behind the control signal, resulting in an extended vulcanization time.
Reason: The heating plate has a large heat capacity and the medium circulation is slow.
Solution: Use materials with better thermal conductivity (such as copper alloy heating plates), or add a preheating stage.
Sensor failure
Phenomenon: Abnormal temperature display leads to unstable vulcanization quality.
Reason: Sensor aging and poor contact.
Solution: Regularly calibrate the sensors and adopt a redundant design (such as mutual backup of dual sensors).
Fifth, the optimization direction of the temperature control system
Intelligent upgrade
Internet of Things (IoT) integration: Remotely monitor the temperature data of the vulcanizing machine through the cloud platform to achieve fault early warning and process optimization.
Machine learning: Training models with historical data to predict the optimal vulcanization temperature curve and reduce trial-and-error costs.
Energy-saving technology
Waste heat recovery: Recover the waste heat from the heating plate during the cooling stage to preheat the next batch of products.
Dynamic power regulation: Adjust the heating power in real time according to the vulcanization progress to avoid ineffective heating.
High-precision control
Nanoscale sensors: Higher-precision temperature sensors (such as platinum resistance PT1000) are adopted to enhance the resolution of temperature measurement.
Multiphysics simulation: Simulate heat transfer during the vulcanization process through finite element analysis (FEA) and optimize the temperature control strategy.