Nitrogen-protected brazing method of aluminum water tank sandglass pipe

Abstract

The invention discloses a nitrogen-protected brazing method of an aluminum water tank sandglass pipe. According to the nitrogen-protected brazing method, an Al-Si brazing filler metal composite layer which is 3%-6% of the thickness of a material covers the inner part of the sandglass pipe; after a water tank core is assembled, sandglass positions are tightly contacted together under the effect of a clamping force of a brazing clamp; in a brazing process, a brazing flux is not added to braze after the inner part of the sandglass pipe is subjected to degreasing cleaning so that the sandglass pipes are firmly brazed together to form a reinforcing rib. The brazing process disclosed by the invention adopts a nitrogen-protected continuous furnace to braze and the production efficiency is high; the brazing flux does not need to be added into the pipe, thus the manufacturability is very good and the yield is high; the nitrogen-protected brazing method is particularly suitable for industrial batch production. According to the nitrogen-protected brazing method disclosed by the invention, a welding line is full after the brazing and the strength is high; in a static pressure bursting test, a water chamber is invalid after being pressed and sealed and the invalid pressure of a sandglass pipe water tank can be up to more than 0.5MPa. According to the nitrogen-protected brazing method, the brazing flux is not added into the water tank so that the inner cleanliness of a product can be improved and the adverse effects of the brazing flux on an anti-freezing solution can be prevented.

Description

technical field [0001] The invention relates to a brazing process for engine water tanks of medium-sized trucks, heavy trucks, engineering vehicles, etc., in particular to a flux-free brazing method for hourglass tubes of aluminum water tanks in a nitrogen protective atmosphere. Background technique [0002] The water tank, also known as the radiator, is used to cool the coolant of the engine and is a key component to ensure that the engine runs within the normal temperature range. The density of copper is more than three times that of aluminum alloy, and the price of copper is more than three times that of aluminum alloy, so the cost of aluminum water tank is about one tenth of that of copper water tank, and the composite aluminum material technology makes aluminum water tank more advanced than copper water tank. The process is easier. It is the general trend to replace copper water tanks with aluminum water tanks. With the improvement of the reliability and lightweight re...

AI Technical Summary

Problems solved by technology

However, it is very difficult to use the conventional Nocolock brazing process at the internal hourglass position under nitrogen protection. The main reason is that the internal height is only 1.3-1.5mm, and the length is 600-1000mm. It is difficult for Nocolock flux to fully enter the required Location

If there is not enough Nocolock flux, it will be difficult to remove the oxide film, resulting in poor brazing, and the reliability will be greatly reduced. However, it cannot be detected without destructive tests in the production process, which will bring a great risk of three-guarantee compensation.

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