A A honed seamless tube is a high-precision steel tube manufactured through cold drawing or hot rolling, followed by a honing process on the inner surface. It features no oxidation layer, high dimensional accuracy, high surface finish, and the ability to withstand high pressure without leakage. It resists cold bending deformation and cracking during expansion or flattening. These properties make it ideal for producing hydraulic and pneumatic cylinder barrels and other precision mechanical components.

A The process begins with selecting qualified carbon or alloy structural steel bars. Steps include: raw material preparation, piercing and hot rolling to form a seamless tube blank, annealing heat treatment, straightening, deep hole drilling if necessary, honing the inner bore with abrasive stones to achieve required dimensions and finish, and finally turning and polishing the outer diameter and end faces to specification. Each finished tube then undergoes rigorous dimensional checks, pressure testing, and leak testing.

A Roller burnishing is a chipless cold-working process that plastically deforms the inner surface to achieve both finishing and strengthening simultaneously. It leaves a beneficial residual compressive stress layer that helps close micro-cracks and hinders corrosion propagation, thereby improving fatigue strength. The process also forms a cold-work hardened layer that reduces elastic and plastic deformation, enhances wear resistance, and avoids grinding burns. It is a highly efficient method that grinding alone cannot replicate.

A Roller burnishing uses hardened rollers to apply pressure on the tube’s inner surface at room temperature. The metal flows plastically from surface peaks into adjacent valleys, significantly reducing surface roughness. This plastic deformation creates a cold-worked, hardened layer with refined, fiber-like grain structure and residual compressive stress. As a result, the surface achieves higher hardness, improved wear resistance, better corrosion resistance, and enhanced fatigue strength, while also improving the fitting characteristics of the bore.

A Advantages include high precision and improved shape accuracy of the bore. The honed surface has a cross-hatch pattern that retains lubricating oil, providing excellent load-bearing capacity and wear resistance. The process can machine a wide range of cylindrical holes—through holes, blind holes, keyway bores, and stepped holes. It removes minimal stock while achieving desired accuracy. Honing also possesses strong error-correction ability, improving roundness, straightness, cylindricity, and surface roughness of the bore.

A Honing is a precision abrasive machining process that uses a rotating and reciprocating tool with mounted abrasive stones. It improves the dimensional accuracy, roundness, straightness, and cylindricity of the bore while achieving a specified surface finish. The process creates a characteristic cross-hatch pattern ideal for oil retention. Because the honing tool is typically floated and self-centering, it can correct shape errors within the bore but cannot correct positional errors such as misalignment relative to other features.

A Heat treatment, including annealing, normalizing, quenching, and tempering, is essential to achieve the required mechanical properties. It refines the steel's microstructure, relieves internal stresses from previous cold working, and enhances strength, toughness, and fatigue resistance. Without proper heat treatment, the tube may suffer from poor machinability, dimensional instability, or insufficient mechanical performance under the complex stresses—tension, compression, bending, torsion—that it faces in service as structural or pressure-containing components.

A Quenching and tempering (Q&T) involves heating the steel to a high temperature, rapidly cooling it to form a hard martensitic structure, then reheating to between 500–650°C to temper it into a tougher structure called tempered sorbite. This treatment provides an excellent combination of high strength and good toughness, known as comprehensive mechanical properties. For components like shafts, connecting rods, and cylinder barrels that must endure dynamic loads, Q&T ensures long-term reliable performance under complex stress conditions.

A Annealing is performed to soften the tube after piercing or cold working, making it more formable and machinable for subsequent processing steps. Correct annealing temperature is crucial; if too high or too low, the desired material properties will not be achieved. After annealing, the tube is pickled in acid to remove scale, then coated with oil for lubrication and corrosion protection before further cold drawing or finishing operations. This cycle may be repeated multiple times to achieve the final dimensions.

A The production method includes heating the tube billet, hot piercing, annealing, hot rolling on a cold pilger mill, stress-relief annealing, acid pickling to remove scale, phosphating to create a zinc phosphate conversion coating, saponification for lubrication, cold drawing to final size, further heat treatment to reduce residual stress, honing on a CNC honing machine, and finally hot straightening. This sequence yields a high-strength tube with precise dimensions and a smooth internal threaded surface.