Spindle forgings are important forgings in hydraulic power station equipment, the quality requirements are very strict, whether to avoid problems in the forging process is directly related to its quality. According to the actual production experience, this paper made a detailed analysis of the appearance of the concave core of the end face before forging, and optimized the forging process.
1. Spindle forgings shape characteristics
Spindle forging shape characteristics: nozzle end flange diameter is large, the middle part of the diameter is small, diameter drop is large, nozzle end a circle diameter, small length.
2. Forging process before optimization
The original deformation process of forging process is: press jaw, cut nozzle discard & RARR; The first upsetting, KD drawing length → The second upsetting, KD drawing length → The finished product is finished by drawing and cutting material. The disadvantages in the forging process are as follows: the drawing and cutting fire times, the concave core of the end face is serious when the first round of the nozzle end is being cut, which leads to the insufficient length of the first round of the nozzle end after the concave core is removed, and the drawing and lengthening need to be re-cut from the large circle, resulting in the waste of raw materials and the reduction of the effective utilization rate of the ingot. In addition, the finished forging fire times increased.
3. Cause analysis
(1) the finished flange diameter is larger, a second upsetting, restricted by high diameter ratio, KD long pull of a smaller reduction billet shuikou face no effective drum belly, flat end face, long pull under way, with a round nozzle end and feeding are relatively less, pressure cannot be passed to the core, makes the nozzle end face form hollow heart.
(2) The anvil used for drawing and cutting material is not clearly specified in the process. The width of the flat anvil is 1200mm and 850mm usually used in our 150MN hydraulic press. The amount of fire deformation of the finished product is large.
(3) When the temperature of the billet is close to the lower limit of forging temperature range, the amount of pressing down will be reduced to prevent the billet from cracking. In this case, the formation of concave core on the end face will be aggravated by drawing and blanking.
4. Process optimization
Aiming at the above problems, we optimized the forging process. The optimized process is as follows:
Clamp mouth, water cut & RARR; Special upsetting machine cover upsetting, 1200mm flat V drawing length, rising end blanking & RARR; 850mm upper and lower V drawing long discharge finished product.
(1) Design special upsetting cover plate, the new cover plate has a hole in the center, the contact surface with the blank is an arc transition, and the contact surface with the cover plate is a large drum belly when the blank is upsetting, which can effectively avoid the concave core phenomenon of the blank end face after drawing.
(2) After upsetting for the second time, it directly uses 1200mm V-shaped anvil to draw the length, and the cutting end of the riser is drawn to a suitable size, so as to ensure that the small flange of the riser end of the finished product has enough deformation, to avoid the large deformation of the finished product and the low temperature of the cutting material, and to ensure that the finished product is forged in the first time.
(3) For the firing of the finished product, the V-shaped anvil of 850mm is used to draw and cut the material, and the length of the cutting material at the nozzle end meets H /D≥ 0.3 (h is the cutting length, D is the blank diameter) and H /L≥ 2/3, (h is the cutting length, L is the hammer head width), select a relatively narrow 850mm V-shaped anvil, the relative feed is increased, ensure that there is no obvious concave core at the nozzle end, the cutting length of the nozzle end is reduced by about 300mm.