The tube expander head is the core functional component of a tube expanding machine, directly determining the forming quality, connection tightness and service life of tube-tube sheet joints. Reasonable structural design, parameter matching and material selection are essential to achieve precise, stable and leak-free tube expansion processing. In industrial applications such as boilers, heat exchangers and pressure vessels, standardized design of expander heads is crucial for improving processing efficiency and product reliability.

Structural parameter optimization is the primary design focus of expander heads. A typical expander head consists of a tapered mandrel, rolling rollers and a limit collar, and all structural parameters need precise calibration. The taper angle of the rollers is a key indicator, and the optimal range is 9° to 12° to avoid excessive expansion force or self-locking failure during operation. The number of rollers, usually three to five, is configured according to tube specifications: more rollers ensure uniform force distribution for large-diameter tubes, while three-roller structures are suitable for small and medium-sized tubes to guarantee flexible operation. Meanwhile, the gap between the head outer diameter and the tube inner diameter must be controlled within 0.3 mm to prevent processing deviation and premature tool wear.

Material performance selection directly affects the durability and processing stability of expander heads. Working under continuous friction and extrusion stress, expander heads require high hardness, wear resistance and mechanical strength. High-strength alloy steel or cemented carbide is the preferred material, with the mandrel hardness maintained at HRC 60-62 and roller hardness at HRC 62-65. This hardness matching effectively avoids surface galling and structural deformation during repeated expansion. In addition, the thermal expansion coefficient of the head material must coordinate with the processed tube material to offset thermal deformation caused by friction heat and ensure processing accuracy under high-strain working conditions.

Accuracy control and structural stability design are also indispensable. The head must maintain high concentricity to ensure uniform radial expansion of the tube wall and avoid local thinning or cracking. The limit collar is designed to accurately position the rollers, adapting to different tube sheet thicknesses and standardizing expansion depth. Moreover, modular and adjustable structural design is adopted in modern expander heads, which can adapt to various tube diameters and improve tool versatility while ensuring processing tolerance within a precise range.

In conclusion, the design of tube expander heads requires comprehensive consideration of structural parameters, material properties and precision control. Scientific design optimization effectively improves tube joint tightness, prolongs tool service life and meets the high-precision processing requirements of industrial tube fitting operations.