Insufficient strength of the heat exchange tubes or side plates in the outermost channel of a tube-belt radiator can lead to deformation or cracking under assembly pressure, vibration, or accidental impact, which may eventually result in coolant leakage. This is a very common issue in engineering practice. So, how can it be fundamentally resolved?
I. Causes of Insufficient Strength in the Outermost Channel
1.Lack of Support: The inner heat exchange tubes are mutually supported by cooling fins, forming a stable integrated structure. In contrast, one side of the outermost channel is open, supported by only a single layer of contact points.
2.Stress Concentration: During assembly, the clamping force from the frame or gasket, along with operational vibration stress, concentrates on these outermost support points.
3.Manufacturing Weak Points: During brazing or welding, the outermost channel experiences the greatest thermal contraction. The joint area with the header tank may cool too rapidly, leading to incomplete soldering or cold solder joints, creating the weakest link in terms of strength.
II. Structural Design and Connection Reinforcement Measures
1.Increasing Side Plate Thickness and Width
Measure: Replace the outermost heat exchange tube with a dedicated "side plate" that is thicker and wider. Side plates are typically made from the same material as the tubes (e.g., brass, aluminum) but are 1.5 to 2 times thicker or more, with width also potentially increased.
Advantage: Directly increases the bending section modulus, making it the primary method for enhancing stiffness and strength.
Application: This is currently the most standard and widespread practice in mainstream radiator manufacturing.
2.Adding External Reinforcement Fins
Measure: Add a layer of special "support fins" or "reinforcement fins" between the outermost channel and the side plate. These fins feature taller crests, thicker material, or are designed with specific reinforcing rib structures.
Advantage: Provides elastic external support for the outermost channel, effectively distributing pressure and suppressing outward bulging and vibration. Offers significant effect with limited cost increase.
3.Optimizing the Connection Between Header Tank and Side Plate
Increase Overlap Area: Design the overlap area between the side plate and the header tank to be larger than that for standard tubes.
Use Reinforced Weld Fillets: Ensure that the weld or braze fillet at the side plate is full and continuous during welding/brazing, creating an effective "reinforcing rib" function.
4.Modifying Side Plate Design
Measure: Design the radiator's side plate with a "hemmed" or "flanged" structure that partially wraps around the outermost channel, providing lateral support.
Advantage: Provides strong mechanical constraint, preventing the outermost channel from being excessively crushed inward or bending during assembly.
III. Material and Process Enhancement Measures
1.Using Higher-Strength Materials
Measure: Employ higher-strength alloy materials for the outermost channel's side plate. For example, in aluminum radiators, while using 3003 aluminum alloy for standard tubes, use slightly stronger alloys like 3005 or 3105 for the side plate.
Advantage: Enhances strength at the material source.
Disadvantage: May lead to cost increases and require adjustments to welding/brazing processes.
2.Ensuring Welding/Brazing Quality
Cleanliness: Ensure absolute cleanliness in the assembly areas of the side plate and header tank, free from oil contamination and oxide layers.
Brazing Filler Application: Ensure a sufficient and uniform layer of brazing filler material is applied in the side plate area.
Furnace Temperature Profile: Optimize the brazing furnace temperature curve to ensure the side plate area (typically the coolest part of the radiator) also reaches the perfect brazing temperature, forming a high-quality brazed joint.
3.Designing the Outermost Channel as a Process Support Channel
Design the outermost flat tube as a sealed process support channel by welding it shut. This is the most direct and effective method, but it must also meet the radiator's thermal performance requirements.
In practical operation, close communication with the radiator manufacturer is essential. Conduct Finite Element Analysis (FEA) to simulate stress distribution, and validate the effectiveness of reinforcement measures through vibration tests and pressure pulse tests. This integrated approach helps identify the most economical and reliable solution.
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