Casting mould having a ventilation duct

Claim 2

A casting mold having a ventilation duct, a ventilation valve in the duct, a recess in communication with the mold cavity, a pressure-sensitive membrane forming part of the wall of the recess, and actuating means responsive to flexion of the membrane, under the influence of the pressure of casting material entering the recess, to initiate closure of the valve.

Claim 3

A mold as claimed in claim 1, in which the membrane being arranged in an extension of the ventilation duct.

Claim 4

A mold as claimed in claim 1, in which the membrane is held in a liquid-tight but movable manner at its periphery.

Claim 5

A mold as claimed in claim 1, including, adjacent to and spaced from the side of the membrane which is remote from the recess, a Rigid support surface for supporting the depressed membrane.

Claim 6

A mold as claimed in claim 1, in which the actuating means includes a displacement member adapted to be displaced by the membrane during deformation, the said member being adjacent to the side of the membrane which is remote from the recess.

Claim 7

A mold as claimed in claim 5, in which the actuating means further comprises a pneumatic control valve having a displaceable valve body arranged to be displaced by the displacement member.

Claim 8

A mold as claimed in claim 6, in which the valve body has the same direction of movement as the displacement member and is urged into the closed position against the action of the displacement member.

Claim 9

A mold as claimed in claim 1, in which the membrane, when not subjected to the pressure of the casting material, bulges into the recess.

Claim 10

A casting mold having a ventilation duct, a ventilation valve in the duct, a recess in communication with the mold cavity, a pressure-sensitive membrane forming part of the wall of the recess, and actuating means responsive to flexion of the membrane, under the influence of the pressure of casting material entering the recess, to initiate closure of the valve, the recess being in communication with the mold cavity via the ventilation duct, the ventilation duct has in the part between the recess and the valve outlet at least locally a smaller flow cross-section than at any point between the recess and the mold cavity.

Claim 11

A casting mold having a ventilation duct, a ventilation valve in the duct, a recess in communication with the mold cavity, a pressure-sensitive membrane forming part of the wall of the recess, and actuating means responsive to flexion of the membrane, under the influence of the pressure of casting material entering the recess, to initiate closure of the valve, the recess being in communication with the mold cavity via the ventilation duct, the ventilation duct has in the part between the recess and the valve outlet at least locally a smaller flow cross-section than at any point between the recess and the mold cavity.

Claim 12

A casting mold having a ventilation duct, a ventilation valve in the duct, a recess in communication with the mold cavity, a pressure-sensitive membrane forming part of the wall of the recess, and actuating means responsive to the flexion of the membrane, under the influence of the pressure of casting material entering the recess to initiate closure of the valve, wherein the mold is in two parts having a plane of separation, the recess being directly adjacent to this plane, and the membrane extending substantially parallel to this plane.

Claim 13

A casting mold having a ventilation duct, a ventilation valve in the duct, a recess in communication with the mold cavity, a pressure-sensitive membrane forming part of the wall of the recess, and actuating means responsive to the flexion of the membrane, under the influence of the pressure of casting material entering the recess to initiate closure of the valve, wherein the mold is in two parts having a plane of separation, the recess being directly adjacent to this plane, and the membrane extending substantially parallel to this plane.