Die-casting machine with injection assembly with a shut-off valve
An injection assembly ( 2 ) of a hydraulic machine for diecasting is provided with a main shut-off valve ( 50 ) suitable to prevent the return of fluid from the main pressure chamber ( 30 ). The main valve ( 50 ) comprise a containment case ( 541 ), in which a return spring ( 540 ) is housed, suitable to retain any rupture fragments thereof.
1. An injection assembly of a hydraulic machine for die-casting, comprising an injection piston, a main inlet for inputting a fluid under pressure, a main pressure chamber upstream of the injection piston and a main shut-off valve normally in a closed configuration, operating between the main inlet and the main pressure chamber and adapted to prevent the fluid from returning from the main pressure chamber to the main inlet, wherein:
the main shut-off valve comprises a shutter and a spring adapted to operate permanently on the shutter towards the closed configuration, and containment means adapted to create a barrier to prevent spring break-up fragments from passing to the main pressure chamber;
the containment means comprise a containment case adapted to accommodate the spring and contain any spring break-up fragments thereof; and
the containment case comprises a movable shell integral with the shutter and a fixed shell, fixed relative to the shutter.
2. An injection assembly according to claim 1 , wherein the movable shell comprises a movable bottom, placed in axial abutment to a shutter abutment wall, and a movable annular containment wall, projecting from the movable bottom, which surrounds a part of the spring.
3. An injection assembly according to claim 2 , wherein a spring end stands on the movable bottom.
4. An injection assembly according to claim 1 , wherein the fixed shell comprises a fixed bottom and a fixed annular containment wall, projecting from the fixed bottom, which surrounds a part of the spring.
5. An injection assembly according to claim 4 , wherein a spring end stands on the fixed bottom.
6. An injection assembly according to claim 4 , wherein the fixed annular containment wall and a movable containment wall axially overlap by a length, leaving a free cavity for passage of fluid from inside of the containment case to outside of the containment case and vice versa.
7. An injection assembly according to claim 1 , wherein the containment case comprises slots adapted to allow passage of fluid from inside of the containment case to the outside of the containment case.
8. An injection assembly according to claim 7 , wherein a movable shell of the containment case comprises a plurality of slots made through a movable containment wall.
9. An injection assembly according to claim 7 , wherein a fixed shell of the containment case comprises a plurality of slots made through a fixed containment wall.
10. An injection assembly according to claim 1 , wherein the main shut-off valve is provided with an inlet opening towards a main inlet, and wherein the shutter comprises a head adapted to close the inlet opening and a shaft projecting from the head opposite to said inlet opening.
11. An injection assembly according to claim 10 , wherein the head has a main surface, facing the inlet opening, consisting of a truncated-cone surface with a rounded vertex.
12. An injection assembly according to claim 10 , wherein the main shut-off valve comprises an outer casing, wherein the outer casing comprises an upstream body, provided with the inlet opening, and a downstream body, provided with outlet openings, with said bodies beings coupled so as to create an inner compartment wherein the shutter is translated.
13. An injection assembly according to claim 12 , wherein the outer casing comprises a bottom base having said outlet openings and comprising a guide for translatably guiding the shutter.