Patent ID: 12208588

DETAILED DESCRIPTION

FIGS.1to3show an exemplary embodiment of a mould which is designated10as a whole, and intended for curing or vulcanisation of a tyre (not shown) for an agricultural vehicle. After moulding, the tyre is annular in form and comprises a cylindrical tread extended by first and second opposite side walls.

On the figures, the mould10is illustrated in an assumed vertical position. Axis X-X′ of the mould10coincides with the axis of revolution of the tyre.

As illustrated more clearly onFIG.3, the mould10comprises a lower portion12, an upper portion14and a ring of central sectors16axially interposed between the lower and upper portions. In the closed position of the mould illustrated inFIG.3, the lower12and upper portions14and the plurality of sectors16jointly delimit a moulding cavity18of the tyre. The closed position of the mould10corresponds to the tyre moulding position.

The lower12and upper portions14and the sectors16are centred on axis X-X′. The sectors16are circumferentially distributed around said axis. The sectors16are mutually identical. The sectors16bear one against the other in the circumferential direction. The lower12and upper portions14and the sectors16may be made of metallic material, in particular steel. The sectors16may comprise an aluminium moulding insert.

As will be described in more detail below, the mould10furthermore comprises, for each sector16, a pair of lower20and upper coupling members22for obtaining a displacement of said sector in a particular movement sequence from its moulding position on opening of the mould, and a reverse displacement on closure of said mould. The sectors16are movable jointly.

The lower12and upper portions14of the mould are identical and symmetrical with respect to a radial median plane of the mould10perpendicular to axis X-X′.

The lower portion12comprises an annular lower shell26and an annular lower ring28radially surrounding the shell26. The shell26and the ring28partially delimit the mould cavity18. The shell26ensures moulding of one of the side walls of the tyre, while the ring28ensures moulding of a side portion of the tyre tread adjacent to said side wall. The shell26comprises an annular lower face26afor moulding the side wall of the tyre. The ring28comprises an annular inner face28afor moulding the side portion of the tread.

The lower portion12also comprises an annular lug30for moulding one of the side beads of the tyre. In the exemplary embodiment illustrated, the shell26, the ring28and the lug30are produced as one block. Alternatively, the shell26, the ring28and the lug30may be separate parts. The shell26and the ring28may be fixed to a common plate.

The upper portion14is identical to the lower portion12, so will not be described in detail. In a similar fashion to the lower portion12, the upper portion14comprises an upper shell36provided with an inner moulding face36a, a lower ring38provided with an inner moulding face38a, and a lug40.

In the closed position of the mould10, each sector16is axially interposed between the rings28,38of the lower and upper portions. Each sector16ensures the moulding of a zone of the central portion of the tyre tread. Each sector16has an inner face16afor moulding this zone of the central portion of the tread. The inner faces16aof the sectors and the inner faces28a,38aof the rings of the lower12and upper portions14ensure the moulding of the tyre tread. These inner faces16a,28aand38aallow the moulding of the profiles of the tyre tread.FIG.3does not show the imprint for the profiles of the tread on the inner face16aof the sector, nor the inner faces28a,38aof the rings.

As illustrated more clearly onFIG.4, each sector16comprises two opposite radial lower and upper front faces16b,16cwhich axially delimit the inner face16a. Each sector16also comprises an outer face16dof tapered form, which lies opposite the inner face16ain the radial direction.

In the closed position of the mould10, the ring28of the lower portion comes to bear axially against the lower front face16bof each sector, and the ring38of the upper portion comes to bear axially against the upper front face16cof each sector. Each ring28,38is also radially engaged against the outer face16dof each sector.

Each ring28,38comprises a radial support face28b,38bwhich radially extends the inner moulding face28a,38aand comes to bear axially against the front face16b,16cof each sector. Each ring28,38also comprises a tapered holding face28c,38cwhich extends the support face28b,38bradially towards the inside and axially towards the outside. The holding face28c,38cof each ring28,38comes to bear radially against the complementary outer face16dof each sector.

Each sector16also comprises a fixing flange16eradially extending the outer face16dtowards the outside. The flange16eprotrudes radially towards the outside relative to the rings28,38. Each sector16is also equipped with two support uprights42fixed on either side of the flange16ein the circumferential direction. The uprights42are situated at a distance from the rings28,38.

Each sector16also comprises first and second guide fingers44,46extending transversely between the uprights42. The fingers44,46are axially arranged on either side of the flange16eof the sector. The fingers44,46extend perpendicularly relative to the axial and radial directions of the mould.

As indicated above, coupling members20,22are associated with each sector16for ensuring the movable mounting of said sector relative to the rings28,38.

The upper coupling member22is fixed to the upper portion14. The coupling member22is fixed to the ring38of the upper portion. The coupling member22is fixed to the outer surface (not designated) of the ring38. The coupling member22comprises a guide groove48, inside which the first finger44of the associated sector extends. The groove48comprises a vertical, rectilinear, axial portion48awhich is extended at a lower end by an oblique portion48bthat extends downward on the side opposite the ring38. The groove48is oblong. The grooves48here passes through the thickness of the upper coupling member22. The groove48is delimited in the width direction by two mutually facing opposite side walls, and in the length direction by two opposite end walls that are here of rounded form.

In the closed position of the mould10, the finger44of each sector is housed in the axial portion48aof the groove and comes to stop axially against the end wall of said axial portion. A metal plate50is fixed to the upper coupling member22so as to ensure the locking of the associated sector during the opening and closing phases of the mould, as will be described in more detail below. The plate50is here fixed to the coupling member22on the side of the ring38of the upper portion. To ensure this locking of each sector16with the associated coupling member22, magnets (not shown) are fixed to the fixing flange16eand to the uprights42of said sector.

The lower coupling member20is fixed to the lower portion12. The coupling member20is fixed to the ring28of the lower portion. The coupling member20is fixed to the outer surface (not designated) of the ring28. The coupling member20comprises a guide groove52, inside which the second finger46of the associated sector extends. The groove52comprises a vertical, rectilinear, axial portion52awhich is extended at an upper end by an oblique portion52bthat extends upward on the side opposite the ring28. The end of the oblique portion52bof the groove is open towards the outside. The groove52is oblong. The groove52is delimited in the width direction by two mutually facing opposite side walls, and in the length direction by an end wall situated at the level of the axial portion52a.

In the closed position of the mould10, the finger46of each sector is housed in the axial portion52aof the groove and comes to stop axially against the end wall of said axial portion. The lower coupling member20also comprises a protruding portion54extending obliquely towards the outside, which extends the lower side wall of the oblique portion52bof the groove.

With reference toFIGS.5to10, we will now describe the opening of the mould10. From the closed position of the mould10again illustrated inFIG.5, the lower12and upper portions14move axially away from one another.

As illustrated onFIG.6, during a first phase of this axial distancing movement, the fingers44,46of each sector slide axially inside the axial portions48a,52aof the grooves of the coupling members22,20. The axial dimension of the axial portions48a,52aof the grooves is provided so as to ensure the disengagement of the sectors16from the rings28,38of the lower and upper portions. When the fingers44,46are situated at the end of the axial portions48a,52aof the grooves, the axial distancing of the lower12and upper portions14is such that a first axial spacing exists between each sector16and the ring38, and a second axial spacing between each sector and the ring28.

During this first phase of the axial distancing movement of the lower12and upper portions14, no movement of the sectors16takes place. Each sector16is still in its moulding position.

Then in a following second phase of the axial distancing movement of the lower12and upper portions14, the fingers44,46of each sector slide inside the oblique portions48b,52bof the grooves of the coupling members22,20, as illustrated inFIG.7. During this second phase, a radial displacement of each sector16takes place towards the outside from its moulding position. Each sector16is thus movable in the radial direction from its moulding position towards a retracted position. For information, the radial retraction of the sector16is of the order of 30 mm in the exemplary embodiment illustrated. It is naturally possible to provide other values for the radial displacement.

When the finger44of each sector bears against the end wall of the oblique portion48bof the groove of the coupling member22, the finger46of said sector is situated outside the open oblique portion52bof the groove of the coupling member20. In this position, each sector16is therefore no longer coupled to the lower portion12via the lower coupling member20.

Each lower coupling member20thus forms a member for temporary coupling of the associated sector16to the lower portion12of the mould, the upper coupling member22forming a member for permanent coupling of said sector to the upper portion14.

Then during the continued axial distancing movement of the lower12and upper portions14, in a third phase, each sector16pivots angularly towards the outside of the mould, as illustrated inFIG.8. The angular pivoting of each sector takes place around the finger44of said sector forming the pivot axis. The angular pivoting of each sector16is a rotation of said sector around the finger44in the counter-clockwise direction. For information, the angular pivoting of the sectors is of the order of 10° in the exemplary embodiment illustrated. Here too, it is also possible to provide other angular values for this pivoting.

The angular pivoting of each sector16becomes possible because the finger46of said sector is no longer engaged with the side walls delimiting the oblique portion52bof the grooves of the lower coupling member20. The angular pivoting of each sector16occurs insofar as before pivoting, the centre of gravity of the sector is radially offset towards the inside of the mould relative to the finger44.

In the exemplary embodiment illustrated, during the angular pivoting of each sector16in the counter-clockwise direction, the finger46of said sector moves along the protruding portion54of the associated lower coupling member20. This contact between the finger46of each sector and the associated coupling member20is not necessary for the angular pivoting of the sector16during this opening phase of the mould10, but allows the return of said sector to its retracted, unpivoted position during a closing phase of the mould10, as will be described in more detail below.

During pivoting of each sector16, the uprights42of said sector come to rest against the metal plate50of the associated upper coupling member22in the region of the magnets mounted on said sector. This causes the locking of the sector16in its pivoted position by the magnetic attraction of the magnets fixed to the uprights42and the flange16eof each sector.

The axial distancing of the lower12and upper portions14continues in a fourth phase, illustrated inFIG.9. Finally, in a fifth and final phase of opening of the mould10, illustrated inFIG.10, the upper portion14pivots angularly relative to the lower portion12in the counter-clockwise direction up to its maximum opening position.

With reference toFIGS.11to15, we will now describe the closure of the mould10from this maximum opening position.

In a first phase of closure of the mould10, illustrated inFIG.11, the upper portion14pivots angularly relative to the lower portion12clockwise, in order to return to a position in which the two portions face one another axially.

Then in a second phase of closure of the mould10, the lower12and upper portions14move axially closer together, as illustrated inFIG.12. In the position shown onFIG.12, the finger46of each sector comes into contact with the protruding portion54of the lower coupling member20associated with said sector.

Then, during the further of axial approaching movement of the lower12and upper portions14, in a third phase, each sector16pivots angularly towards the inside of the mould, as illustrated onFIG.13. The angular pivoting of each sector16takes place under the effect of contact between the finger46of said sector and the protruding portion54of the lower coupling member20. The angular pivoting of each sector16takes place in the clockwise direction around the finger44of said sector. Each sector16is thus returned to its retracted position with respect to its moulding position. During this phase of the axial approaching movement of the lower12and upper portions14, the angular pivoting of each sector16takes place as soon the reaction force exerted on the finger44by the protruding portion54of the coupling member20exceeds the magnetic attraction force of the magnets of the sector.

In a fourth phase of the axial approaching movement of the lower12and upper portions14, the fingers44,46of each sector slide inside the oblique portions48b,52bof the grooves of the coupling members22,20, as illustrated onFIG.14. During this phase, a radial displacement of each sector16takes place towards the inside from its retracted position up to its moulding position. Each sector16is in its retracted position when the fingers44,46of said sector are situated at the ends of the oblique portions48b,52bof the grooves connecting to the axial portions48a,52a.

Finally, during a fifth and final phase of the axial approaching movement of the lower12and upper portions14, the fingers44,46of each sector slide axially inside the axial portions48a,52aof the grooves of the coupling members22,20until the rings28,38come to bear axially against the sectors16in the closed position of the mould, illustrated inFIG.15.

During closure of the mould10, the sectors16thus move in a reverse movement sequence to that which occurs during opening of said mould.

Also, as indicated above, in the exemplary embodiment illustrated, during the opening phase when the finger44of each sector is situated at the end of the oblique portion48bof the groove of the coupling member22, the finger46of said sector is situated outside the open oblique portion52bof the groove52of the coupling member20. As a variant, it would be possible to provide an elongated oblique portion52bfor the groove52, while however ensuring that the side walls of this portion widen towards the outside so as not to later hinder the angular pivoting of the sector.

The invention has been described on the basis of a mould allowing moulding of a tyre for an agricultural vehicle. It is possible, without leaving the scope of the invention, to use such a mould with sectors for manufacture of a tyre for any land-based vehicle, including and without limitation vehicles of the types passenger vehicle, utility vehicle, heavy goods vehicle or also construction vehicle.