Company name: wuxi tianfeng metal products co. LTD
Address: no. 39, zhenze road, huazhuang street, economic development zone, wuxi city, jiangsu province (old factory area)
Address: no.210-2, chengnan road, wangzhuang industrial supporting area (new), new district, wuxi city, jiangsu province
Contact person: +86-1377 1199 895
How to solve the folding defect of shaft forgings?
In forgings, most of them are shaft forgings, and their forming molds are formed by the upper and lower parts. In forging, the forgings rotate around the axis and have no flash, such as clamping molds and aligning molds. The feature of die drop forming is to restrict the transverse flow of metal through the side pressure of the mold, so that the metal can be extended along the axis. Compared with the free forging forming, the elongation rate can be increased by 20% ~ 40%. At the same time, the stress condition can also prevent the longitudinal crack in the interior. It is found in the production that the folding defect often occurs in the step part when the step shaft forgings are forged by the general die.
1. Folding defects. The following is the process of half-axle forging, to illustrate the use of forming steps in the process of shaft defects, and the improvement of the solution. Half axis forming step is: (1) pressure shoulder diameter is 130mm; (2) pull both ends of the length to the diameter of 130mm, free forging forming; (3) one end pressure shoulder diameter 118mm; (4) pull the long end to the diameter of 115mm, free forging forming; (5) pressure shoulder diameter 108mm; 6 pull the other end to the diameter of 105mm, free forging forming; 7 trimming and straightening forming, straightening die. Use falling out of the mold, in the step (), (), (7), 7, are prone to fold defects, especially in the straight falling out of the mold this step is serious.
2. Problem analysis. Now take the step of straightening die drop as an example to analyze the cause of defects and process improvement. Steps are generated in different parts of the mold cavity, and the height is determined by combining the diameter difference, so that the steps are not severely deformed and the flow is not smooth in the forging process. When the upper and lower modules are closed, the rounded corner on the cavity is set to avoid the concentration of stress and smooth the flow, which will cause a step gap at the place where it contacts the step and further affect the metal flow. In this way, in the step part, except that most of the metals flow according to the tooling to produce steps, the rest of the metals flow because of the diameter change is not free, some of them flow into the gaps of the upper and lower modules, forming a "flash" like die forging. During the rotary forging of the forging piece, the remaining metal of this part will be stuck on the surface of the forging piece due to its thin thickness, which will be bent during the forging, and will get stuck in the forging piece and form a fold when it is further forged. There are two reasons for the folding defects in the ordinary die falling: one is the steps in the cavity with different diameters; The other is the rounded corners of the cavity. For the analysis of these two factors: (1) the round corner of the cavity can not be canceled; (2) folding began to appear at the junction of the modules, indicating that close to its contact site steps are the main cause of folding.
3. Problem solving. Modify the tooling to solve the folding problem of shaft forgings. At the step of die dropping, two tangents are set in the tangential direction of small diameter circular arc and the tangential Angle of large diameter circular arc. This partially eliminates the presence of steps in the contact parts of the module, slowing the shape change. When the modules are closed, a cavity is created in the rounded corner to accommodate the remaining metal, rather than the original step gap. Forging left over to the metal parts, no flash, and produce a prismatic block, when forging rotary forging, this part of the remaining metal because is prismatic due to its thickness after folding, so is not the first bending but after forging rough and forging and then melt into forging internal, as a whole, folding defects will not occur.