plastic forming

Today, let's take a look at plastic forming, one of the eight major metal forming processes

Plastic forming: refers to the process of using the plasticity of materials to process parts with little or no cutting under the external force of tools and molds. There are many types of it, mainly including forging, rolling, extrusion, drawing, stamping, etc.

(1) Forging and forging: It is a processing method that uses forging machinery to apply pressure to metal billets, causing plastic deformation to obtain forgings with certain mechanical properties, shapes, and sizes.

According to the forming mechanism, forging can be divided into free forging, die forging, ring rolling, and special forging.

Free forging: Generally, it is a machining method that uses simple tools to hammer metal ingots or blocks into the desired shape and size on a hammer forging or hydraulic press.

Die forging: It is formed using a mold on a die forging hammer or hot die forging press.

Ring rolling: refers to the production of circular parts with different diameters using specialized equipment ring rolling machines, and is also used to produce wheel shaped parts such as car wheels and train wheels.

Special forging: including roll forging, cross wedge rolling, radial forging, liquid die forging and other forging methods, these methods are more suitable for producing certain special shaped parts. Process flow: forging billet heating → roll forging preparation billet → die forging forming → edge cutting → punching → correction → intermediate inspection → forging heat treatment → cleaning → correction → inspection

Technical characteristics: 1) The quality of forgings is higher than that of castings, and they can withstand a greater impact force. The plasticity, toughness, and other mechanical properties are also higher than those of castings or even higher than those of rolled parts. 2) Save raw materials and shorten processing hours. 3) Examples of high production efficiency. 4) Free forging is suitable for single piece small batch production and has greater flexibility.

Application: The rollers and herringbone gears of large steel mills, the rotors, impellers, and retaining rings of steam turbine generators, the huge working cylinders and columns of hydraulic presses, locomotive shafts, crankshafts and connecting rods of automobiles and tractors, etc.

2) Rolling: A pressure processing method in which metal billets pass through the gaps (various shapes) of a pair of rotating rollers, and are compressed and formed by the rollers, resulting in a reduction in material cross-section and an increase in length.

Rolling classification: According to the movement of rolled parts, there are longitudinal rolling, transverse rolling, and oblique rolling.

Longitudinal rolling: refers to the process in which metal passes between two rolls with opposite directions of rotation and undergoes plastic deformation between them. Cross rolling: The movement direction of the rolled piece after deformation is consistent with the axis direction of the rolling roller. Cross rolling: The rolled piece moves in a spiral motion, and the axis between the rolled piece and the roll is not at a specific angle. Application: Mainly used in metal profiles, plates, pipes, and other non-metallic materials such as plastic and glass products.

(3) Squeeze extrusion: The processing method in which the billet is extruded from the hole or gap of the mold under three uneven compressive stresses, reducing its cross-sectional area and increasing its length, to become the desired product is called extrusion. This processing of the billet is called extrusion forming.

Process flow: preparation before extrusion → heating of casting rod → extrusion → stretching, twisting, straightening → sawing (fixed length) → sampling inspection → manual aging → packaging and warehousing

Advantages: 1) Wide production range, multiple product specifications and varieties; 2) High production flexibility, suitable for small batch production; 3) The product has high dimensional accuracy and good surface quality; 4) Low equipment investment, small factory area, and easy to achieve automated production.

Disadvantages: 1) Large loss of geometric waste; 2) Uneven metal flow; 3) Low extrusion speed and long auxiliary time; 4) High tool wear and tear, high cost.

Production scope: mainly used for manufacturing long rods, deep holes, thin-walled, and special-shaped cross-sectional parts.