Fuel Injection Valve Sintered Magnetic Metal Element

The patent applies preliminary action by performing press working on a green compact (unsintered state) rather than on the final sintered valve element. This preliminary shaping is done when the material is most compliant and can be formed without inducing deformation, as the green compact has not yet undergone the volumetric changes that occur during sintering. The pressing force is applied before the sintering process, avoiding the dimensional instability that would occur if pressing were applied to the sintered material.

The patent implements beforehand cushioning by using a green compact with controlled porosity (3-7%) as a cushioning medium during press working. This porous green compact structure absorbs and distributes the pressing force uniformly, preventing localized deformation and swelling. The porosity acts as a cushion that allows the material to be shaped while accommodating volume changes during subsequent sintering without compromising dimensional stability.

The patent applies self-service by designing the valve element so that the green compact structure itself provides the necessary smooth movement characteristics during sintering. The controlled porosity (3-7%) and the resulting expansion behavior during sintering create a self-smoothing effect that eliminates the need for separate finish machining operations. The material essentially finishes itself through the controlled sintering process, achieving the required surface smoothness and dimensional stability without additional machining steps.

The patent utilizes parameter changes by controlling the porosity parameter of the green compact (3-7%) to achieve the desired final properties. By adjusting this critical parameter during the green compact formation, the sintering process produces a valve element with optimal dimensional stability and smooth movement characteristics. This parameter control allows the material properties to change predictably during sintering, eliminating the need for post-machining operations.

The patent applies preliminary action by performing all necessary shaping and forming operations on the green compact before sintering. The press working is done while the material is still in its unsintered state, allowing the geometry to be established without the constraint of maintaining a dense, stress-prone sintered structure. This sequence prevents deformation by eliminating the need to apply pressing forces to already-sintered material that would induce residual stresses.

The patent implements beforehand cushioning by using the porous green compact structure as a cushion during the press working operation. The controlled porosity (3-7%) provides a compliant medium that absorbs and distributes pressing forces uniformly, preventing the induction of residual stresses in the final sintered structure. This cushioning effect is only possible in the green compact state, not in the dense sintered material.