GB1577154A - Pre-moulded retread assembly for the rebuilding of pneumatic tyres - Google Patents

Description

(54) PRE-MOULDED RETREAD ASSEMBLY FOR THE REBUILDING OF PNEUMATIC TYRES (71) We, MARANGONI R.T.S. RING TREAD SYSTEM - S.P.A. of Ferentino.

Frosinone, Italy, a Body Corporate organised under the Laws of Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be described in and by the following statement: - This invention relates to a pre-moulded retread assembly utilizable in the retreading of pneumatic tyres.

As well known, pneumatic tyres, especially if of large dimension, may be advantageously reutilized by the application on their carcass of a tread ring or band consisting of pre-moulded rubber.

The "cold-process' rebuilding methods, namely by pre-moulded material provide the use of a pre-moulded band or ring having a width correlated to that of the pneumatic tyre to be covered, being mounted on the pneumatic tyre having been formerly worked so as to cover the surface to be regenerated.

It is likewise well known that for a good regeneration of a pneumatic tyre is would be necessary that the covering layer would be suitably extended on the sides or flanks of the pneumatic tyre itself.

In this manner in fact there would be obtained an almost total rebuilding of the carcass as far as the proximity of the beads of the pneumatic tyre and hence as far as pneumatic tyre areas away from the points subjected to heating and stress.

In order to attain the aforesaid result, consequently, it would be necessary to make pre-moulded rings, provided with most extended flanks.

In practice, however, the building of such ring type of curved section, is practically impossible, especially in the case of large dimension pneumatic tyres, such as pnuematic tyres for aircraft or "earthmoving equipment".

As a matter of fact, by using premoulded closed rings, the difficulties arise in the execution of the same with extended flanks and subequent mounting on the already prepared pneumatic tyre.

Conversely, by using for the covering of the pneumatic tyre a pre-moulded flatsection band or strip, the edge of the band may get down very little on the flanks of pneumatic tyre.

This is due to the fact that the diameter of the pneumatic tyre varies considerably, starting from its larger section towards the flanks, whereas the flat section band, as being horizontally molded, shows a development of constant length.

According to the present invention there is provided a premoulded retread assembly for the retreading of worn pneumatic tyres, the assembly being adapted to cover both the crown surface and at least the upper portions of the side wall surfaces of the worn tyre and including two premoulded annular half-treads. each half-tread having an outer surface provided with tread grooves and an inner surface which is curved to enable the half-tread to be located on the tyre surface on a respective side of the plane cutting the tyre periphery through its largest diameter, the outer and inner surfaces of each half-tread defining therebetween a portion shaped to cover at least the radially outer portion of a side wall surface.

The two half-treads can, of course, be applied on two opposite sides of the pneumatic tyre.so as to touch with each other perfectly in the middle portion of the same.

Each half-tread, because of its particular structure does not involve any difficulties in assembly, since all diameters are degrading in one single Idirection.

Equally simple is their mounting on the surface of the pneumatic tyre surface to be covered, inasmuch as the rings themselves show a section defined by a curved segment with tangents of diverging extremities.

The pre-moulded half-treads can also be used to cover pneumatic tyres of equal diameter, but having a greater width. In such case, in fact, it just suffices to place between the two half-treads a ring of suitable width, grooved or not.

This possibility is most important in practice, inasmuch as it ensures to arrange a plurality of half-treads of a determined diameter for the fabrication and rebuilding of pneumatic tyres of equal diameter, but with different sections.

The subsequent treatments to which the pneumatic tyres covered with the retread assembly of this invention are subjected are the traditional ones, namely in autoclave, with loose pneumatic tyre; in autoclave with inflated pneumatic tyre separately, closed between circles and elastic hose in order to prevent air from filtering between the retread assembly and the carcass; under pressure by using heated moulds without grooving and with pneumatic tyre in inflated condition; at appropriate atmospheric pressure and temperature with the use of special putties, etc.These and further characteristic features of a functional and constructional nature of the pre-molded retread assembly with extended flanks for the full rebuilding and fabrication of pneumatic tyres according to the present invention could better be understood from the following detailed description, taken in conjunction with the figures on the accompanying drawings, in which: Fig. 1 shows in a perspective form the half-treads, removed from the pneumatic tyre; -Fig. 2 represents in a schematic form a section of the pneumatic tyre covered with the half-treads as given in Fig. 1; and -Fig. 3 depicts a pneumatic tyre similar to that given in the preceding figures, but of larger section, covered with two halftreads as per Fig. 1 with the interposition of an annular member.

Referring now particularly to the figures on the accompanying drawings, the premolded retread assembly for the rebuilding of pneumatic tyres is made up of two halftreads 1 and 1', consisting of rubber each having a curved section delimited on the inner surface by a circle arc'2.

Each half-tread 1 or 1' on the outer surface is provided with a suitable grooving 3 and shows the edge 4, elongated and extended downwardly so as to cover sufficiently part of the radially outer side walls 5 of the pneumatic tyre 6 to be rebuilt.

Between the two half-treads 1 and 1' providing the covering of the carcass of the pneumatic tyre 6 there may be interplaced a ring 7 of substantially rectangular section so as to fully cover the active surface of the retread assembly in case the two-half-treads are not properly in contact with each other.

The ring 7 may show a smooth surface or a grooved surface. From the foregoing and perusal of the figures on the accompanying drawings one may easily see the great functional character and practical application characterizing the pre-molded retread assembly for the rebuilding of pneumatic tyres according to the present invention.

Several changes and modifications may be introduced, of course. upon carrying out this invention without departing from the scope of the invention itself.

WHAT WE CLAIM IS: 1. Premoulded retread assembly for the retreading of worn pneumatic tyres, the assembly being adapted to cover both the crown surface and at least the upper portions of the side wall surfaces of the worn tyre and including two premoulded annular half-treads, each half-tread having an outer surface provided with tread grooves and an inner surface which is curved to enable the half-tread to be located on the tyre surface on a respective side of the plane cutting the tyre periphery through its largest diameter, the outer and inner surfaces of each half-tread defining therebetween a portion shaped to cover at least the radially outer portion of a side wall surface.

2. Assembly as claimed in claim 1 in which each half-tread has a surface opposite to the tyre flank covering portion, the surface being adapted for face to face relationship with the corresponding surface of the other half-tread.

3. Assembly as claimed in claim 1 in which a ring is provided of substantially rectangular section for location between the two half-tread.

4. Premoulded retread assembly for the retreading of worn pneumatic tyres substantially as hereinbefore described with reference to any of Figures 1, 2 or 3.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. covered, inasmuch as the rings themselves show a section defined by a curved segment with tangents of diverging extremities. The pre-moulded half-treads can also be used to cover pneumatic tyres of equal diameter, but having a greater width. In such case, in fact, it just suffices to place between the two half-treads a ring of suitable width, grooved or not. This possibility is most important in practice, inasmuch as it ensures to arrange a plurality of half-treads of a determined diameter for the fabrication and rebuilding of pneumatic tyres of equal diameter, but with different sections. The subsequent treatments to which the pneumatic tyres covered with the retread assembly of this invention are subjected are the traditional ones, namely in autoclave, with loose pneumatic tyre; in autoclave with inflated pneumatic tyre separately, closed between circles and elastic hose in order to prevent air from filtering between the retread assembly and the carcass; under pressure by using heated moulds without grooving and with pneumatic tyre in inflated condition; at appropriate atmospheric pressure and temperature with the use of special putties, etc.These and further characteristic features of a functional and constructional nature of the pre-molded retread assembly with extended flanks for the full rebuilding and fabrication of pneumatic tyres according to the present invention could better be understood from the following detailed description, taken in conjunction with the figures on the accompanying drawings, in which: Fig. 1 shows in a perspective form the half-treads, removed from the pneumatic tyre; -Fig. 2 represents in a schematic form a section of the pneumatic tyre covered with the half-treads as given in Fig. 1; and -Fig. 3 depicts a pneumatic tyre similar to that given in the preceding figures, but of larger section, covered with two halftreads as per Fig. 1 with the interposition of an annular member. Referring now particularly to the figures on the accompanying drawings, the premolded retread assembly for the rebuilding of pneumatic tyres is made up of two halftreads 1 and 1', consisting of rubber each having a curved section delimited on the inner surface by a circle arc'2. Each half-tread 1 or 1' on the outer surface is provided with a suitable grooving 3 and shows the edge 4, elongated and extended downwardly so as to cover sufficiently part of the radially outer side walls 5 of the pneumatic tyre 6 to be rebuilt. Between the two half-treads 1 and 1' providing the covering of the carcass of the pneumatic tyre 6 there may be interplaced a ring 7 of substantially rectangular section so as to fully cover the active surface of the retread assembly in case the two-half-treads are not properly in contact with each other. The ring 7 may show a smooth surface or a grooved surface. From the foregoing and perusal of the figures on the accompanying drawings one may easily see the great functional character and practical application characterizing the pre-molded retread assembly for the rebuilding of pneumatic tyres according to the present invention. Several changes and modifications may be introduced, of course. upon carrying out this invention without departing from the scope of the invention itself. WHAT WE CLAIM IS:

1. Premoulded retread assembly for the retreading of worn pneumatic tyres, the assembly being adapted to cover both the crown surface and at least the upper portions of the side wall surfaces of the worn tyre and including two premoulded annular half-treads, each half-tread having an outer surface provided with tread grooves and an inner surface which is curved to enable the half-tread to be located on the tyre surface on a respective side of the plane cutting the tyre periphery through its largest diameter, the outer and inner surfaces of each half-tread defining therebetween a portion shaped to cover at least the radially outer portion of a side wall surface.

2. Assembly as claimed in claim 1 in which each half-tread has a surface opposite to the tyre flank covering portion, the surface being adapted for face to face relationship with the corresponding surface of the other half-tread.

3. Assembly as claimed in claim 1 in which a ring is provided of substantially rectangular section for location between the two half-tread.

4. Premoulded retread assembly for the retreading of worn pneumatic tyres substantially as hereinbefore described with reference to any of Figures 1, 2 or 3.