Round‑Outer Hex‑Inner Steel Pipe: Ideal for Torque Transmission

Round outer and hexagonal inner steel pipe is a high‑precision special‑shaped profile tube with a circular outer surface and a hexagonal inner bore. It combines the excellent bending resistance of round tubes and the high torque‑transmission stability of hexagonal structures, making it widely used in precision machinery, automotive, aerospace, automation, and other industrial fields.

The core advantage of this pipe lies in its unique cross‑section. The round outer diameter ensures easy installation, rolling support, and uniform stress distribution, while the inner hexagonal bore enables zero‑slip torque transmission, precise positioning, and stable fitting with hexagonal shafts, screws, or transmission parts. Compared with conventional round inner pipes, it greatly improves transmission efficiency, reduces assembly clearance, and enhances overall structural rigidity and anti‑twisting capacity.

Main Functions

1. High‑Efficiency Torque TransmissionThe hexagonal inner bore provides large contact area and even force distribution, effectively preventing slipping during rotation. It is ideal for drive shafts, couplings, and power‑transmission components.
2. Precise Positioning and Anti‑RotationIt locks the relative position of matching parts, avoiding radial rotation and ensuring stable operation under vibration or shock loads.
3. High Strength and Lightweight StructureWith good bending, torsion, and pressure resistance, it can replace solid bars or welded components to reduce weight while maintaining strength.
4. Stable Connection and Easy AssemblyThe round outer surface is compatible with standard fixtures, bearings, and mounting structures, while the inner hexagon simplifies fast assembly and disassembly.

Typical Applications

• Automotive & Machinery: Camshaft sleeves, drive shafts, universal joints, hydraulic cylinder piston rods
• Industrial Robots: Joint shafts, transmission tubes, precision actuators
• Aerospace: Landing gear parts, high‑pressure hydraulic lines, engine components
• Agricultural Machinery: Transmission shafts, assembly connectors for tillers and harvesters
• Power Tools & Hand Tools: High‑torque tool shanks, handles, and extension bars
• New Energy Equipment: Solar tracker drives, wind turbine transmission parts