锻造论文文献翻译
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- 锻造论文文献翻译
Bulk defirnnation of metals refers to various processes, such as forging, rolling, or extruding, where there is a controlled plastic flow or working of metals into useful shapes. The most well known of these processes is forging where deformation is accomplished by means of pressure, impact blows, or a combination of both.
Hammer Forging
Hanuner forging consists of striking the hot metal with a large semiautomatic hammer. If no dies are involved, the forging will be dependent mainly on the skill of the operator. If closed or impression dies are used, one blow is struck for each of several (lie cavities. A- gain, productivity and quality depend to a large degree on the skill of the hanimer operator and the tooling.
Press Forging
Press forging is characterized by a slow squeezing action. Again, open or closed dies may be used. The open dies are used chiefly for large, simple-geometry parts that are later machined to shape. Closed-die forging relies less on operator skill awl more on the design of the preform and forging dies.2 As an example of the versatility of the process, newer developments have made it possible to produce bevel gears with straight or helical teeth. Rotation of the die (luring penetration will press bevel gears with spiral teeth.
Open-die Forging
Open-die forging is distinguished by the fact that the metal is never completely confined as it is shaped by various dies. Most open-die forgings are produced on flat, V, or swaging dies. Round swaging (lies and V dies are used in pairs or with a flat die. The top (lie is attached to the ram of the press, and the bottom die is attached to the hammer anvil or, in the case of press open-die forging, to the press bed.
As the workpiece is hammered or pressed, it is repeatedly manipulated between the dies until hot working forces the metal to the final dimensions, as-shown in Fig. 1. After forging, the part is rough- and finished-machined. As an example of the amount of material allowed for machining, a 6.5 in. diameter shaft would have to be forged to 7.4 in. dianieter.
In open-die forging of steel, a rule of thumb says that 50 lb of falling weight is required for each square inch of cross section.
Impression-die Forging
In the simplest example of impression-die forging, two dies are brought together, and the workpiece undergoes plastic deformation until its enlarged sides touch the side walls of the die (Fig. 2). A small amount of material is forced outside the die impression, forming flash that is gradually thinned. The flash cools rapidly and presents increased resistance to deformation, effectively becoming a part of the tool, and helps build up l)ressUre inside the bulk of the work- piece that aids material flow into unfilled impressions....
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