Industrie Pirelli S.p.a.

Societa' Pneumatici Pirelli

Achille Gallizia

Paolo Bandel

Giorgio Tangorra

A process and a device for forming a tennis ball by the formation of two semispherical bowls in crude elastomeric material each having on its border a structural shape that is deformed by compression when the two semispherical bowls are pressed one against the other while a depressurization is effected in the joining zone of the two semispherical bowls on the outside of them.

Device for manufacturing closed hollow bodies in elastomeric material

An extruder head for extruding an elastomeric composition to form a reinforced elastomer article such as a conveyor belt has a substantially rectangular die opening and a guide member disposed in the opening of the die for directing the reinforcing elements into the composition as it is shaped by the die. A device is provided for restricting the streams of composition, which flow on opposite sides of the guide member, to have said flow meet said reinforcement along two parallel fronts.

Flat extruder head

The invention provides a process for the injection molding of treads on a tire carcass which comprises feeding an elastomeric composition for molding the tire's tread to a plurality of equalization spaces symmetrically arranged with respect to the injection cavity of the mold where the tread is formed, the mix moving to the injection cavity from each of the spaces through a plurality of injection passages, the mix being fed to each of the spaces through at least one feeding passage and the ratio between average sliding gradients .gamma..sub.i of the injection passages and gradients .gamma..sub.a of the feeding passages being not lower than 8. The invention also provides an apparatus for the injection molding of a tread on a tire body having a plurality of feeding channels symmetrically arranged around the injection cavity, a plurality of equalization chambers arranged with the same symmetry and into which the feeding channels flow, and a plurality of injection orifices which connect each chamber with the cavity, the ratio between the sections of the injection orifices and the section of the feeding channels and the number of injection orifices where the delivery of each feeding channel spreads, being such that, when a fluid mix for molding the tread is flowing through them, the ratio between respective gradients .gamma. of average sliding is not lower than 8.

Equipment for the injection molding of motor vehicle tire treads

A mold for molding a boot or similar footwear from an elastomeric composition and simultaneously lining the footwear with a fabric, has first and second shells each having a cavity which complements the cavity of the other to form a large cavity which corresponds to the upstanding sides of the footwear and a third shell which has a cavity corresponding to the sole thereof. The three shells are assembled together with a rigid core member enclosed therein which defines the inside of the boot. The core member has an elastically expandable casing. Conduits are arranged in the core member for conveying a fluid under pressure to expand the casing.

Device for manufacturing boots and the like of elastomeric material

A process and a device are disclosed for forming a tennis ball which comprises the formation of two semispherical bowls in crude elastomeric material each having on its border a structural shape that is deformed by compression when the two semispherical bowls are pressed one against the other while a depressurization is effected in the joining zone of the two semispherical bowls on the outside of them.

Process for manufacturing closed hollow bodies in elastomeric material

An apparatus is provided for injection molding a pneumatic tire having corresponding symmetrical parts such as the sidewalls of the tire which are geometrically symmetrical and have substantially the same physical characteristics. The apparatus involves means for providing a feed stream of suitable plastic or elastomeric compound such as rubber, separating the feed stream into intermediate streams and remixing the intermediate stream before injection into the mold. The compound is injected into the mold cavities at uniformly spaced points along at least one of the annular zones of the cavity. The feed stream is preferably separated into two streams, one of which comes primarily from the outer portion of the stream and the other predominantly from near the center of the stream and then these streams are intermixed to provide a stream which is substantially uniform in composition throughout. Similarly prepared streams are injected into the two parts of the mold cavity which form a pair of symmetrical parts of the tire such as the two sidewalls.

Apparatus for the injection molding of pneumatic tires having

The invention provides a process for the injection molding of treads on a tire carcass which comprises feeding an elastomeric composition for molding the tire's tread to a plurality of equalization spaces symmetrically arranged with respect to the injection cavity of the mold where the tread is formed, the mix moving to the injection cavity from each of the spaces through a plurality of injection passages, the mix being fed to each of the spaces through at least one feeding passage and the ratio between average sliding gradients .gamma..sub.i of the injection passages and gradients .gamma..sub.a of the feeding passages being not lower than 8. The invention also provides an apparatus for the injection molding of a tread on a tire body having a plurality of feeding channels symmetrically arranged around the injection cavity, a plurality of equalization chambers arranged with the same symmetry and into which the feeding channels flow, and a plurality of injection orifices which connect each chamber with the cavity, the ratio between the sections of the injection orifices and the section of the feeding channels and the number of injection orifices where the delivery of each feeding channel spreads, being such that, when a fluid mix for molding the tread is flowing through them, the ratio between respective gradients .gamma. of average sliding is now lower than 8.

Process for the injection molding of motor vehicle tire treads

A process is provided for molding a tread on a vehicle tire body in which a tire body requiring a tread is supported in a mold which combines with the surface of the tire body to form a cavity conforming to the configuration and dimensions of the tread. The cavity is filled with a flowable vulcanizable elastomeric composition by injection at equally spaced points around the equatorial axis of the mold of measured volumes of material which will combine to fill the cavity and develop a low pressure in the mold cavity to insure flow of material until the cavity is completely filled. The invention also provides an injection molding apparatus having a mold which combines with a tire body supported therein to form a cavity corresponding to the configuration and dimensions of a tire tread. A series of equally spaced openings are provided around the equatorial axis of the mold for injection of molding composition and openings are provided around the sides of the mold cavity for the escape of air from the cavity as it is filled with composition.

Process for injection molding a vehicle tire tread

A process and apparatus are provided for injection molding a pneumatic tire having corresponding symmetrical parts such as the sidewalls of the tire which are geometrical symmetrical and have substantially the same physical characteristics. The process involves providing a feed stream of suitable plastic or elastomeric compound such as rubber, separating the feed stream into intermediate streams and remixing the intermediate stream before injection into the mold. The compound is injected into the mold cavities at uniformly spaced points along at least one of the annular zones of the cavity. The feed stream is preferably separated into two streams, one of which comes primarily from the outer portion of the stream and the other predominantly from near the center of the stream and then these streams are intermixed to provide a stream which is substantially uniform in composition throughout. Similarly prepared streams are injected into the two parts of the mold cavity which form a pair of symmetrical parts of the tire such as the two sidewalls. An apparatus for dividing a feed stream into the intermediate streams and mixing them to form a stream for injection into the mold cavities is also provided.

Process for the injection molding of pneumatic tires having symmetrical

A process for injection molding a crown of a vehicle tire from one composition and the sidewalls from a different composition involves the steps of shaping the reinforcing structure in the mold, injecting a first composition over one side of the reinforcing structure to form a crown with a tread and injecting a second composition to form the sidewalls with an interface within the proximity of the edges of the reinforcing structure. In a preferred embodiment, the tire has the configuration of the one disclosed in U.S. Pat. No. 3,805,868. The annular reinforcing structure is shaped to be generally convex but concave towards the tread along its edges.

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Milan, Italy

Achille Gallizia