Spacer type cooling water channel
In injection mold cooling system design, septum-type cooling channels are widely used in the molding of complex plastic parts due to their efficient heat dissipation capabilities. Traditional straight-through cooling channels struggle to adapt to the curved surfaces or deep cavities of irregularly shaped plastic parts, resulting in uneven cooling. Septum-type cooling channels, however, employ septums within the channels to divide the channels into multiple independent flow paths. This creates turbulent coolant flow and significantly improves heat exchange efficiency. This design is particularly suitable for large, complex plastic parts such as automotive bumpers and appliance housings, effectively shortening cooling time and reducing defects such as warping and sink marks caused by uneven cooling.
The structural design of the septum-type cooling water channel requires precise planning based on the shape and wall thickness distribution of the plastic part. The number and arrangement of the septums directly impacts the cooling effect. Typically, the spacing between the septums is 1-1.5 times the water channel diameter and must maintain a uniform distance from the plastic part surface, generally controlled between 5-10mm. For example, for a curved plastic part with a wall thickness of 3mm, the septum-type water channel can be designed with a diameter of 8mm and a septum spacing of 8mm. This creates strong turbulence in the coolant flow channel, ensuring that the cooling rate deviation in various parts of the plastic part does not exceed 5%. In addition, the connection between the septum and the water channel wall must use an arc transition to avoid increased coolant flow resistance and local dead angles caused by the right-angle structure.
The material selection and processing technology of the spacer-type cooling water channel are crucial to the cooling performance. The mold material is usually made of alloy tool steel with a high thermal conductivity coefficient, such as P20, 718H, etc. These materials can not only transfer heat quickly, but also ensure the structural strength of the spacer. In terms of processing, in the early days, electric spark wire cutting or milling processes were mostly used to make spacers, but the precision was difficult to control, and gaps were easily formed between the spacer and the water channel wall, affecting the cooling effect. With the development of 3D printing technology, the use of selective laser melting (SLM) technology can directly print integrated spacer-type water channels, avoiding the splicing errors of traditional processing, and increasing the connection strength between the spacer and the water channel wall by more than 30%, and the heat exchange efficiency by 15%-20%.
The design of coolant flow parameters is key to the effectiveness of spacer-type cooling channels. The coolant flow rate must be controlled between 1.5 and 3 m/s. A flow rate that is too low will lead to laminar flow in the channel, resulting in inefficient heat exchange. A flow rate that is too high will increase power consumption and may cause erosion and wear on the spacers. At the same time, the temperature difference between the coolant inlet and outlet should be controlled within 5°C. By adjusting the flow rate and temperature, the plastic part is ensured to maintain a uniform temperature field during the cooling process. For example, for large automotive instrument panel molds, a parallel spacer water channel design can be adopted. The coolant flow rate of each independent channel is individually controlled by a valve, ensuring that the cooling rate of the edge and center of the instrument panel is consistent, reducing the cooling time to 60% of the original.
The maintenance and optimization of spacer-type cooling water channels need to be continuously improved in conjunction with production practices. During long-term use, impurities in the coolant may form scale on the surface of the spacers, resulting in a decrease in heat exchange efficiency. Therefore, the water channels need to be cleaned regularly, and chemical cleaning is generally performed every 5,000 molds to remove scale and oil stains. In addition, CAE cooling simulation software can monitor the flow state and temperature distribution of the coolant in real time, and the number and arrangement of spacers can be adjusted based on the simulation results. For example, to address the uneven cooling problem of a certain mobile phone casing mold, by adding two spacers and adjusting the flow channel direction, the cooling time of the plastic part was shortened from 45 seconds to 32 seconds, and the qualified rate was increased from 82% to 98%. In the future, with the application of intelligent sensing technology, spacer-type water channels can be integrated with temperature sensors to achieve real-time dynamic adjustment of the coolant flow rate, further improving cooling accuracy.
