1. Definition of cold forging
Cold forging, also known as cold volume forging, is a manufacturing process as well as a processing method. Basically the same as stamping process, cold forging process is composed of materials, molds and equipment. But the material in stamping processing is mainly plate, and the material in cold forging processing is mainly disk wire. Japan (JIS) called cold forging (cold forging), China (GB) called cold heading, outside screw factory like to call head.
2. Basic concepts of cold forging
Cold forging refers to the metal recrystallization temperature below the various volume forming. According to the theory of metalology, the recrystallization temperature of various metal materials is different. T = (0.3 ~ 0.5) T melt. Minimum recrystallization temperature of ferrous and non-ferrous metals. Even at room temperature or normal temperature, the forming process of lead and tin is not called cold forging, but hot forging. But iron, copper, aluminum forming processing at room temperature can be called cold forging.
In metallics, the forging of materials heated above the recrystallization temperature (about 700℃ for steel) is called hot forging.
For steel forgings, the recrystallization temperature below and higher than normal temperature forging is called warm forging.
Advantages of cold heading (extrusion)
In fastener forming, cold heading (extrusion) technology is a main processing technology. Cold heading (extrusion) belongs to the category of metal pressure processing. In production, at normal temperature, the metal is applied external force, so that the metal in the predetermined mold forming, this method is usually called cold heading.
The forming of any fastener is not only a deformation way of cold heading, it can be realized in the process of cold heading, in addition to upsetting deformation, but also accompanied by forward and back extrusion, composite extrusion, punching cutting, rolling and other deformation ways. Therefore, the name of cold heading in production is only a customary name, and should be called cold heading (squeeze) more accurately.
Cold heading (extrusion) has many advantages, it is suitable for the mass production of fasteners. Its main advantages mainly include the following aspects:
High utilization rate of steel, cold heading (squeeze) is a method of less, no cutting, such as processing rod, cylinder head hex socket screws, hex head bolt machining method, the utilization rate of steel in 25% ~ 35%, and only with cold heading (squeeze) method, and its utilization rate can be as high as 85% ~ 95%, is just a head, tail and hex head cut some of the consumption process.
High productivity: compared with general cutting, cold heading (extrusion) forming efficiency is dozens of times higher than.
Good mechanical properties: cold heading (extrusion) processing of parts, because the metal fiber is not cut, so the strength is much better than cutting.
Suitable for automatic production: fasteners (also including some special-shaped parts) suitable for cold heading (extrusion) production are basically symmetrical parts, suitable for high-speed automatic cold heading machine production, is also the main method of mass production.
In a word, the cold heading (extruding) method is a kind of processing method with high comprehensive economic benefit, which is widely used in the fastener industry. It is also an advanced processing method widely used at home and abroad with great development.
Post time: Oct-30-2021