To solve large and complex Medical titanium rod The forming of forgings provides a feasible method. This method has been widely used in the production of titanium rods. One of the effective ways to improve the fluidity of titanium rod and reduce the deformation resistance Z is to increase the preheating temperature of the die. Isothermal die forging and hot die forging developed in recent twenty or thirty years at home and abroad.

Under the same condition of unit pressure and hammer die forging, when forging with a press. The blank heating temperature can be reduced by 50100 ℃. In this way, the interaction between the heated metal and the periodic gas, as well as the temperature difference between the blank and the die, will also be reduced accordingly, thus improving the uniformity of deformation, the uniformity of the structure of the die forgings will also be greatly improved, and the consistency of mechanical properties will also be improved. The deformation speed is reduced, and the numerical value is increased. The surface shrinkage rate is sensitive to the microstructure defect Z caused by overheating.

The friction with the tool is large and the contact surface of the blank cools too fast. In order to improve the fluidity of titanium rod and increase the service life of die. The usual method is to increase the die forging slope and fillet radius and use lubricant: the height of the burr bridge on the forging die is higher than that of the steel, and the deformation of the titanium bar is more difficult to flow into the deep and narrow die groove than that of the steel. This is because titanium has high deformation resistance. It is generally about 2mm larger. Sometimes, uneven burr grooves at the bridge part can be used to restrict or accelerate the flow of metal to a certain part of the groove. For example, to make the groove easy to fill. The front and rear side walls of a rectangular box forging (as shown in Figure 12) are thinner; The left and right side walls are thick. When the burr grooves shown in B-B are used around the box shaped parts, the metal flow to the thinner front and rear side walls is difficult due to the small resistance of metal flowing into the left and right side walls, and the filling is insufficient. Later, the front and rear sidewalls still use the burr grooves as shown in B-B, while the left and right sidewalls use the burr grooves as shown in A-A. Due to the wide size of the bridge and the obstruction of the damping groove, the front and rear thinner sidewalls are fully filled, and the metal is saved compared with the aforementioned burr grooves.

Due to the high pressure, the service life of titanium bars is reduced. Therefore, when titanium bars are forged by closed die forging, the volume of the original blank must be strictly limited by closed die forging, which complicates the material preparation process. Whether to adopt closed die forging should be considered from two aspects: interest and process feasibility. During open die forging, the rough edge loss accounts for 15% - 20% of the weight of the blank. The technological waste of the clamping part (if required according to the die forging conditions) accounts for 10% of the weight of the blank. The relative loss of the rough edge metal usually increases with the reduction of the blank weight. Some structural asymmetry, large sectional area difference and local forgings that are difficult to fill exist, The rough edge consumption can be as high as 50%. Although there is no rough edge loss in closed die forging, the blank making process is complex and more transition grooves need to be added, which will undoubtedly increase the auxiliary costs.

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