What are the manufacturing processes for ring forgings?

Ring forgings are a product of the forging industry and a type of forging. They are formed by applying external force to a metal billet (not sheet metal) through plastic deformation to form a ring-shaped object with appropriate compressive strength. This force is typically applied using a hammer or a press. The forging process creates a refined grain structure and improves the physical properties of the metal. Ring forgings are a ubiquitous industrial product.

1. Raw Material Selection: Typically, the raw material for ring forgings is steel or alloy steel billet. When selecting the raw material, consider its properties, strength, toughness, wear resistance, and intended use to ensure that the ring forging meets the requirements.

2. Preparatory Processing: Before manufacturing ring forgings, the raw material requires certain preparatory processes, such as removing surface oxide scale and residual impurities, and cutting to the appropriate size for ease of processing and forging.

3. Heating: Before forging, the raw material must be heated to an appropriate temperature, generally above its tempering temperature. The heating temperature should be determined based on factors such as the raw material material and specifications, the shape and size of the ring forging, and the forging method. 

4. Forging: The heated raw material is fed into a hammer press or hydraulic forging machine for forging, forming it into a ring shape. The forging process requires careful attention to factors such as temperature control, hammer force, and frequency. After forging, a slow cooling treatment is required to prevent intergranular corrosion and carburization.

5. Post-Processing: After forging, the ring forging undergoes post-processing, including cutting, trimming, drilling, and surface treatment. This post-processing ensures that the ring forging perfectly meets design requirements.

This process is characterized by rotating tools and continuous deformation, i.e., rolling the ring blank. Rolling expansion generally involves a small reduction, resulting in surface deformation. Ring rolling is a continuous, localized forming process that integrates rolling and mechanical manufacturing technologies. Compared to traditional open-die forging and die forging processes, it offers significant technical and economic advantages.

Magang expansion is primarily used for open-die forging of Custom ring forgings. The stress-strain characteristics of Masteel hole expansion are similar to stretching, but differ from long-axis stretching in that it involves circumferential stretching of the ring forging blank, resulting in localized loading and overall stress.

During Masteel hole expansion, the metal in the deformation zone flows tangentially and widthwise. During Magang hole expansion, the metal in the deformation zone primarily flows tangentially, increasing the inner and outer diameters. Forgings expanded with Magang holes generally have thinner walls, resulting in much less resistance to tangential flow in the outer deformation zone than in the width direction. The curved contact surface between Masteel and the ring forging facilitates tangential flow.

Thus, the dimensional changes in the forging during Magang hole expansion are a reduction in wall thickness, an increase in inner and outer diameters, and a slight increase in width (height). Therefore, for small-batch, small-size rings, Masteel top expansion is more suitable. In summary, the production process of ring forgings includes multiple links such as raw material selection, preparatory processing, heating, forging, and post-processing. The process parameters of each step need to be strictly controlled to ensure that the produced ring forgings have the characteristics of high strength, high toughness, and high wear resistance.