Pressing method of powder molding press

1. Unidirectional pressing

During the pressing process of the powder forming hydraulic press, the female die and the lower punch do not move, and only the upper punch applies the pressing pressure to the powder. Unidirectional pressing is generally suitable for products with a height-to-diameter ratio H/D≤1 or sleeve parts with a height-to-wall thickness ratio H/T≤3.

2. Bidirectional pressing

During the bidirectional pressing of the powder forming hydraulic press, the female die (female die) is fixed, and the upper and lower punches (convex dies) press with a certain magnitude and opposite pressure. According to whether the pressure is applied simultaneously, it can be divided into simultaneous bidirectional pressing and non-simultaneous bidirectional pressing (post-pressing). In the former, the upper and lower punches apply equal pressure to the powder at the same time, and in the latter, after completing a unidirectional pressing, a unidirectional pressing is performed at the low-density end.

3. Floating pressing

During the pressing process of the powder forming hydraulic press, the upper punch presses the powder, the lower punch does not move, and the female die can float up and down through appropriate support such as springs or cylinders, oil cylinders, etc. During pressing, the upper die is pressurized, and as the powder is compressed, the friction between the female die wall and the powder gradually increases. When the friction force is greater than the supporting force (floating force) of the spring, the female die and the upper punch fall together, which is equivalent to the lower punch rising and pressing in the opposite direction to play the role of two-way pressing. In floating pressing, in addition to the floating female die, the core rod can also float. At this time, the density distribution is the same as that of two-way pressing. If the female die floats and the core rod does not move, the compact is close to the female die and is similar to two-way pressing, with the lowest density in the middle; the compact is close to the core rod, which is similar to the one-way pressing of the upper punch moving downward, with the lowest density at the bottom. Floating pressing is suitable for parts with H/T≤6 or H/D≥2.

4. Pull-down pressing

5. Friction core rod pressing

When the powder forming hydraulic press is pressed, the female die and the lower punch are fixed, and the upper punch forces the core rod to move down together, and the core rod moving down speed is greater than the powder moving down speed. The friction between the core rod and the powder can drive the powder to move down, thereby improving the uneven density distribution along the height direction of the compact. This method is suitable for pressing slender and thin-walled parts with H/T>6-10. It is also called pull-down pressing and strong dynamic pressing. At the beginning of the pressing, the upper punch is pressed down a certain distance, and then it descends together with the female die (the female die is forced to be pulled down). The speed of the female die's descent can be adjusted, and the distance it is pulled down is equivalent to the floating distance. At the end of the pressing, the upper punch rises back, and the female die is further pulled down to allow the compact to escape. The characteristics are similar to engineering and floating pressing. Some powders have low friction and cannot be pressed in a floating manner, so this pressing method can also be used.

Dongguan Shengshi Weiye Machinery Technology Co.The main equipment produced are: Liquid Die Forging Machine, low-pressure Casting Machine, Gravity Casting Machine, cold forging machine, hot forging machine, etc