How to choose a bending mandrel

      First, when choosing a copper tube bending mandrel, you need to consider the following key factors:

      Bending radius and wall thickness: Choose a suitable mandrel according to the bending radius and wall thickness of the copper tube. For example, when the ratio of the bending radius to the outer diameter of the copper tube R/D is greater than or equal to 3, and the ratio of the wall thickness to the outer diameter S/D is greater than or equal to 0.05, you can choose a coreless bending tube. For copper tubes with a small bending radius or thin wall thickness, you need to use a hard or soft mandrel to bend the tube.

      Mandrel type: Choose a suitable mandrel type according to the material and bending requirements of the copper tube. Hard mandrels are suitable for general bending requirements, while soft mandrels are more suitable for copper tubes with small bending radius or thin wall thickness. Soft mandrels can adapt to different bending requirements more flexibly.

     Mandrel diameter and gap: The diameter of the mandrel and the gap between it and the inner diameter of the copper tube will also affect the quality and effect of the bending tube. The diameter of the mandrel needs to be appropriate. Too small may cause wrinkles on the inside of the copper tube, while too large or not smooth enough may damage the tube wall. Usually, the diameter of the mandrel should be slightly smaller than the inner diameter of the copper tube to ensure that the copper tube will not be excessively damaged during the bending process.

Lubrication: During the bending process, fully lubricating the mandrel and the inner wall of the copper tube is also an important step to improve the quality of the bending. Proper lubrication can reduce friction, make the bending process smoother, and avoid damage to the inner wall of the copper tube.

      Choosing a suitable copper tube bending mandrel through the above points can ensure the quality of the bent pipe fittings and meet specific engineering or product requirements. When choosing, you can consider the specific bending requirements and the material, wall thickness and other factors of the copper tube and choose the most suitable mandrel type and specification.

     Again, when choosing copper tube, aluminum tube or stainless steel tube bending mandrel, you can follow the following suggestions:

     In particular, in the production and manufacturing of air conditioning refrigeration heat exchangers, copper tubes or aluminum tubes with the following outer diameters are generally bent: Φ5mm, Φ6.35mm, Φ7mm, Φ7.94mm, Φ9mm, Φ9.52mm, Φ12mm, Φ12.7mm, Φ14.5mm, Φ15.88mm, etc. The specifications of stainless steel tubes for bending heat exchangers are generally these: Φ7mm, Φ9.52mm, Φ12.7mm, Φ15.88mm, etc. Whether copper tubes, aluminum tubes or stainless steel tubes, there are long U-shaped bends and U-shaped elbow bends. For long U-shaped copper tubes, universal mandrels are generally used for bending. For small-diameter long U-shaped copper tubes such as Φ5mm, Φ6.35mm, and Φ7mm, a dull mandrel or thumb-shaped mandrel is generally used for bending. For U-shaped copper tube elbows, one-way mandrels are generally used for bending, and dull mandrels or thumb-shaped mandrels can also be used for bending. At present, many manufacturers have begun to use aluminum tubes instead of copper tubes in refrigeration heat exchangers. Generally speaking, the aluminum tube bending mandrel is the same as the copper tube bending mandrel, but because the aluminum tube has strong viscosity and high requirements for the surface of the bending mandrel, all bending mandrels need to be PVD treated. The mandrel treated in this way has a very good bending effect. For stainless steel heat exchangers in special environments, stainless steel tubes must be bent. The stainless steel bending mandrel is different from the copper and aluminum tube bending mandrels. It needs to be made of cemented carbide materials or special PVD processing technology. Of course, in the manufacturing process of air-conditioning heat exchangers, whether copper tubes, aluminum tubes or stainless steel tubes, there are many process pipe fittings that need to be bent, and the choice of bending mandrel is the same as the above.