The manufacturing process of mechanical hollow shafts mainly includes forging process, cutting process, extrusion casting process, cross wedge rolling process, etc. The following is a detailed introduction:
1、 Forging process
Forging is a common method for manufacturing hollow shafts, which causes plastic deformation of metal materials through pressure and thermal effects, forming hollow shafts with specific shapes and properties. The main steps of forging process include:
Material preparation: Select suitable raw materials such as steel ingots, aluminum ingots, etc., and choose appropriate metal materials based on the required hollow shaft performance.
Preheating: Heating the raw materials to an appropriate forging temperature to reduce internal stress in the metal and improve plasticity.
Forging: Place the heated raw materials into forging equipment (such as forging hammers, presses, rolling mills, etc.), and use pressure to cause plastic deformation of the metal, forming the initial shape of a hollow shaft.
Overhauling and elongation: By hammering, rolling, or rolling, the diameter of the hollow shaft is increased or its length is elongated to obtain the desired size.
Forging: Forging the two ends of a hollow shaft to form a complete hollow shaft structure.
Cooling and heat treatment: During the forging process, it is necessary to cool the hollow shaft appropriately to obtain the desired microstructure and mechanical properties. Subsequently, heat treatment (such as normalizing, quenching, tempering, etc.) is carried out as needed to improve its mechanical properties and wear resistance.
Cutting and surface treatment: Cutting hollow shafts to remove surface defects and obtain precise dimensions and shapes. Then surface treatment (such as polishing, coating, spraying, etc.) is carried out to improve the wear resistance, corrosion resistance, and aesthetics of the hollow shaft.

2、 Cutting process technology
For some hollow shafts with high precision requirements, cutting technology is indispensable. The main steps of cutting processing technology include:
Cutting: Cut the raw materials to the required size.
Rough machining: rough machining of the outer circle, leaving sufficient machining allowance.
Drilling: A through hole is machined in the center of the shaft, and after drilling, it needs to be reamed to improve accuracy.
Precision machining: Precision machining of outer circles and inner holes to achieve the required dimensional accuracy and surface roughness.
Spline processing: Use a dedicated puller to process internal/external splines to meet transmission requirements.
Testing: Conduct size, appearance, and performance inspections on the processed hollow shaft to ensure that the product quality meets the requirements.

3、 Squeezing casting process
Squeeze casting is a forming process that falls between casting and forging, combining the advantages of both casting and forging. The main steps of squeeze casting process include:
Mold preparation: Prepare a suitable mold and pour liquid metal directly into the mold cavity.
Squeezing: Applying a certain mechanical pressure to liquid metal in a closed mold cavity through a punch (convex die or core), causing the liquid metal to crystallize, form, and undergo a small amount of plastic deformation under pressure.
Demolding and post-treatment: After the metal solidifies, demolding treatment is carried out, and necessary post-treatment (such as heat treatment, cutting, etc.) is performed on the casting.

4、 Wedge cross rolling process
The cross wedge rolling process has been widely used in forming solid shaft parts, with advantages such as high production efficiency and material utilization, stable forming quality, and good microstructure and properties. For the manufacturing of hollow shafts, the cross wedge rolling process also has its unique applications:
Non core rod rolling forming: suitable for manufacturing hollow shafts with low requirements for inner hole size accuracy.
Rolling forming with core rod: Through the rolling action of the core rod, the inner hole size can be controlled more accurately, which is suitable for the manufacturing of parts with requirements for inner hole size. At the same time, the rolling effect of the core rod can also improve the grain refinement of the rolled piece and enhance the mechanical properties of the parts.