精密锻造成型工艺实操要点｜Impression Die Forging: Preform, Finish and What Controls Fill

摘要：锻件成型靠预锻与终锻两道工步完成。预锻分配金属体积、避免折叠，终锻保证尺寸且不过载；坯料温度、模具润滑、坯料体积、设备吨位四项条件直接决定能否充满型腔。
Abstract: Forming is a two-step operation: preform distributes the metal and prevents laps, finishing sets the dimensions without overloading the press. Billet temperature, die lubrication, billet volume and press capacity decide whether the die fills at all.

正文： 锻造成型依靠锻压机打击，让高温坯料金属流动充满模具型腔，得到目标形状锻件。分为预锻、终锻两道关键工步。
Main text: Forming uses press blows to make hot metal flow into the die cavity and take the required shape. It runs as two critical steps: preform and finish.

一、预锻：先把金属体积分配对
1. Preform: distribute the volume first

预锻型腔对坯料做初步变形，分配金属体积，减少终锻模具磨损，避免终锻出现折叠。形状复杂锻件必须设置预锻。预锻型腔设计要引导金属合理流动，避免金属剧烈对流产生折叠缺陷。
The preform impression does the initial deformation and distributes volume. That reduces wear on the finishing impression and prevents laps from forming in the final blow. Complex shapes cannot skip it. The preform cavity has to guide metal flow in an orderly way; violent convergence of metal streams is exactly what produces laps.

二、终锻：保证尺寸，但别把模具打过载
2. Finish: set the dimensions without overloading the die

终锻工艺：完成最终型腔充型，保证锻件尺寸。控制打击力、打击次数，不要过度打击造成模具过载。
The finishing impression completes cavity fill and sets the final dimensions. Control blow energy and the number of blows; extra blows load the die without improving the part.

三、影响成型的四个条件
3. Four conditions that decide whether it fills

• ① 坯料实际温度：温度过低金属流动性差，充不满型腔；
  1. Actual billet temperature. Too cold and flow stress is high enough that the cavity will not fill.
• ② 模具状态：模具温度、石墨润滑效果；润滑不良会粘模，金属流动受阻；
  2. Die condition. Die temperature and graphite lubrication: poor lubrication causes sticking and blocks metal flow.
• ③ 坯料体积：下料重量不足直接充不满；重量过大飞边太厚。
  3. Billet volume. Underweight billets simply cannot fill; overweight billets give excessive flash.
• ④ 设备打击能量：设备吨位不足会造成打不靠，锻件尺寸不合格。
  4. Press energy. Insufficient tonnage leaves the part not closed to the die faces, and the dimensions fail.

四、常见成型问题与实操
4. Common defects and the working routine

成型常见工艺问题：充型不足、金属回流折叠、锻件打不靠、模具开裂。
The recurring problems are incomplete fill, laps from back-flow, parts not closed to the die, and die cracking.

工艺实操：新产品投产，首件解剖查看金属流线；固化预锻终锻打击次数；同一产品批次保持坯料温度、润滑工艺稳定。
On the floor: for a new part, section the first piece and inspect the flow lines. Freeze the blow counts for preform and finish. Hold billet temperature and lubrication constant across the batch.

小结 精密锻造成型，重点做好预锻分配金属流量，管控坯料温度、模具润滑、设备打击能力，首件确认金属流线，避免折叠充型不良。
In short. In precision forging the work is in the preform: distribute the metal, hold billet temperature, die lubrication and press energy, and confirm the flow lines on the first piece. Laps and short fills follow from those four things.