Optimization of forging process for spindle forgings

Spindle forgings are important forgings in hydraulic power plant equipment, and have very strict quality requirements. Whether problems can be avoided in the forging process is directly related to its quality. Based on the actual production experience, this paper makes a careful analysis of the concave center in the end face of the forge and optimizes the forging process.

1. Shape characteristics of spindle forgings

Spindle forging shape characteristics: nozzle end flange diameter is large, the middle part diameter is small, diameter drop is large, nozzle end a circle diameter is large, length is small.

2. Optimize the forging process before

The deformation process of the original forging process is as follows: pressing jaw, cutting mouth & RARR; The first upsetting, KD pulling → The second upsetting, KD pulling → Pull out the finished product. There are drawbacks in the forging process: drawing long discharging fire times, when the spout end is a round discharging, the end face concave center is serious, resulting in the length of the spout end is not enough after the concave center is removed, and it is necessary to draw long from the big circle discharging, resulting in waste of raw materials and reduced effective utilization rate of steel ingot. In addition, 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 process is not clear about the type anvil used for drawing and blanking. Our 150MN hydraulic press usually uses two kinds of flat anvil widths of 1200mm and 850mm, and the fire deformation of the finished product is large. He uses the 1200mm wide anvil to draw the length of the fast speed, which aggravates the formation of the end face concave.

(3) The fire deformation of the finished product is large and the time is long. When the billet temperature is close to the lower limit of the forging temperature range, in order to prevent the billet cracking, the amount of pressure down will be reduced. At this time, the drawing and discharging will also aggravate the formation of the end face concave.

4. Process optimization

Aiming at the above problems, we optimized the forging process, and the optimized process is as follows:

Pressure clamp mouth, cutting mouth & RARR; Special upsetting machine cover upsetting, 1200mm upper and lower V drawing length, riser end cutting & RARR; 850mm upper and lower V pull long material out of the finished product.

(1) The special upsetting cover plate is designed. The center of the new cover plate has a hole, and the contact surface with the billet is an arc transition. The contact surface of the billet upsetting with the cover plate is in a large bulging shape, which effectively avoids the concave phenomenon in the subsequent drawing of the billet end face.

(2) After the second upsetting, the upper and lower V-shaped anvil of 1200mm shall be directly used to draw the length, and the riser end shall be drawn to an appropriate size to ensure that the small flange of the riser end of the finished product has enough deformation, to avoid the end face concave of the finished product due to the large deformation of the finished product and the low temperature of the blanking material, so as to ensure that the finished product can be forged in one fire.

(3) The finished product fire time is 850mm on the flat bottom v-shaped anvil drawing length, and the feeding length at the nozzle end should meet h/D≥ 0.3 (h is blanking length, D is blank diameter) and H /L≥ Under the condition of 2/3, (h is the feeding length, L is the hammer head width), a relatively narrow 850mm v-shaped anvil is selected to increase the relative feed, and on the premise that there is no obvious concave center at the nozzle end, the feeding length at the nozzle end is reduced by about 300mm than the original.