Classification of gear forging

There are many ways to forge gears. Gear forging can be classified as follows:

According to different gear forging tools and production processes, it can be divided into free forging, die forging and special forging. Free forging is a processing method that uses simple universal tools to produce plastic deformation of metal (mostly heated metal) on forging equipment to obtain forgings with size, shape and performance meeting the requirements. It can be divided into manual free forging and its free forging.

The main forming methods of die forging are open, closed, extrusion and upsetting. Open die forging refers to the flow of metal in the incompletely restricted die cavity to generate gear forgings with the same shape as the die cavity. It has high forming consistency, but there are transverse flash. Closed die forging and closed upsetting are similar to open die forging, but due to the absence of flash, the utilization rate of materials is higher, After forging, one or several processes can complete the finishing of complex gear forgings. Die forging requires expensive molds, which is only suitable for product trial production or mass production.

Special gear forging refers to the use of special forging equipment to meet various requirements of gear forgings. Special gear forging machinery has strong specificity. It can only produce a certain type of products by gear forging, which is suitable for the production of large quantities of parts.

2 according to the temperature required for gear forging, gear forging can be divided into hot forging, warm forging and cold forging. Hot forging, that is, gear forging is carried out when the temperature is higher than the recrystallization temperature of the blank metal. At this temperature, the material fluidity is enhanced, and the gear forging can be completed under small impulse pressure. The material utilization rate is low, the die is easy to be damaged, and the accuracy is not high.

Warm forging: when the temperature is kept below the recrystallization temperature of the blank metal but higher than the room temperature for gear forging, the metal fluidity is reduced, and the gear forging needs to be completed under large impulse pressure. The material utilization rate is higher than hot forging, and the utilization rate is higher than hot forging. Compared with cold forging, the die is easy to be damaged, and the accuracy is between hot forging and cold forging.

Cold forging is generally gear forging at room temperature. The metal fluidity is the worst, the required punching pressure is the largest, the material utilization rate is the highest, the service life of the die is the highest and the precision is the highest.

3 according to the accuracy, gear forging can be divided into ordinary forging and precision forging. Ordinary forging has low requirements, low precision of die and low precision of gear forging size and shape. Now most forging products are still in the ordinary forging level.

Precision gear forging refers to forging with die forging process on the press, and the shape, dimensional tolerance, surface quality and other indicators are higher than those of ordinary gear forging. After the gear is forged and formed, it only needs a small amount of processing or no processing to meet the requirements. At present, there are many precision forging processes that have been applied to production, including hot precision forging, warm precision forging, cold precision forging, compound precision forging Isothermal precision forging, etc. in the process of precision forging, the deformation resistance of forgings is greater than that of general gear forging, and the die life is longer. Precision forging is the development trend of forging.

Open or closed die forging is mostly used for gear forging. According to the die conditions, hot forging, warm forging or cold forging process can be adopted. The gear forging process of pre forging with hot forging or warm forging and then tooth profile finishing with cold forging can reduce the tonnage of press required for early deformation and ensure the gear accuracy in the finishing process.

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