The present invention relates to a method of manufacturing a reinforced
component of a motor vehicle tire carcass, in particular, a body ply and/or tread
In known tire manufacturing plants, reinforced components, such as
a body ply or tread ply, are usually formed from textile cords which, after undergoing
a series of processing operations, are arranged parallel to form the axial warp
of a textile strip.
Said processing usually consists in a calendering operation, whereby
both sides of the textile strip are coated with rubber to produce a rubber-coated
strip in which the cords are arranged axially. The rubber-coated strip is then
subjected to a cutting and splicing operation, whereby it is cut into portions,
the cutting direction being substantially perpendicular to the axial warp for
body plies, and at an angle of other than 90° to the axial warp for the tread plies.
Said portions are then turned through 90° and the original lateral ends spliced
to form a composite strip constituting the required reinforced component, in which
the cords are arranged transversely or at a given angle in relation to the longitudinal
axis of the composite strip.
By virtue of the number of operations required for producing said
composite strip, the above method of manufacturing said reinforced component clearly
involves considerable cost. Moreover, said composite strip presents a number of
transverse splices which may result in unacceptable vibration of the finished tire.
A further drawback of known reinforced components of the aforementioned
type is that each cord portion inside the component originates from a respective
cord of ideally infinite length fed on to the press and having its own "history"
independent of that of the adjacent cords. In other words, by virtue of containing
a large number of independent cord portions in terms of age, composition (which
cannot be absolutely identical for all the cords), humidity, elasticity, size,
etc., known reinforced components of the aforementioned type contain numerous
independent, at times uncontrollable, variables making consistent results extremely
difficult to achieve.
The aim of the present invention is to provide a method of manufacturing
a reinforced component of a motor vehicle tire carcass, in particular a body ply
and/or tread ply, designed to overcome the above drawbacks. With this aim in view,
according to the present invention, there is provided a method of manufacturing
a reinforced component of a motor vehicle tire carcass, in particular a body ply
and/or tread ply, characterised by the fact that it comprises stages consisting
in feeding at least one elongated reinforcing element on to a surface along a
substantially sinusoidal path, to form a reinforcing layer defined by a succession
of straight, substantially parallel portions of said elongated reinforcing element,
said straight portions of the same element being joined successively by curved
end portions; moving said reinforcing layer substantially transversely in relation
to said straight portions, so as to cooperate with an extrusion unit; and applying,
by means of said extrusion unit, a covering layer of uncured elastomeric material
on to at least one side of said reinforcing layer, to produce said reinforced
component; said covering layer preferably consisting of a shaped covering layer
varying in thickness in the direction of said portions of said elongated reinforcing
According to a preferred embodiment of the above method, said elongated
reinforcing element is preferably a cord coated with uncured elastomeric material.
Said extrusion unit preferably comprises at least one extruder of
A non-limiting embodiment of the present invention will be described
by way of example with reference to the accompanying drawings, in which:
- Fig.1 shows a schematic view in perspective of a manufacturing machine implementing
the method according to the present invention for producing a first type of reinforcing
- Fig.2 shows an axial section of part of the Fig.1 machine;
- Fig.3 shows an end view of the machine portion in Fig.2;
- Fig.4 shows a plan view of the machine portion in Fig.2, with parts removed
- Fig.5 shows a cross section of a first reinforcing element produced on the
Fig.1 and 4 machine operating in the Fig.4 mode;
- Fig.6 shows a plan view, similar to Fig.4, of the Fig.1 and 3 machine in a
further operating mode;
- Fig.7 shows a cross section of a second reinforcing element produced on the
Fig.1 and 4 machine operating in the Fig.6 mode.
Number 1 in Fig.1 indicates a machine for manufacturing reinforced
components of motor vehicle tires, such as a body ply 2 (Fig.5) and/or a tread
ply 3 (Fig.7).
Machine 1 comprises a known feeding device 4 for feeding a cord 5,
preferably coated with uncured elastomeric material, to a distributing device 6,
which feeds cord 5 on to a surface defined by the top branch 7 of the belt 8 of
a conveyor 9. Belt 8 is looped about two rollers 10 and 11 fitted on to respective
parallel horizontal shafts 12 and 13, shaft 12 being powered so as to turn about
its axis (clockwise in Fig.1) and feed belt 8 at a given constant speed in the
direction of arrow 14 and perpendicular to the axes of shafts 12 and 13.
As shown more clearly in Fig.s 2, 3 and 6, distributing device 6
comprises a block 15 having two horizontal through holes 16 and 17. Hole 16 is
a smooth cylindrical hole engaged in sliding manner by a guide rod 18 supported
on a mobile support (not shown) enabling rod 18 to be oriented between a horizontal
position perpendicular to the direction of arrow 14 (Fig.4) and a horizontal position
(not shown) at an angle of about 60° to the direction of arrow 14. Hole 17 is a
threaded hole connected, via a screw-nut screw coupling, to a screw 19 constituting
the output member of an actuating device 20 (Fig.1) orientable with rod 18 and
designed to slide block 15 back and forth along rod 18 and over substantially
the entire width of belt 8.
Block 15 presents a further through hole 21 perpendicular to branch
7 of belt 8 and communicating, at the top, with a funnel 22 for feeding cord 5
inside hole 21 and, at the bottom, with an output piece 23 facing branch 7.
As shown in Fig.s 4 and 6, the outer surface of belt 8 presents two
rows 24 and 25 of appendixes 26. Rows 24 and 25 are located close to the opposite
longitudinal edges of belt 8, the appendixes 26 in one row being offset, in the
direction of arrow 14, in relation to those of the other.
Consequently, by feeding belt 8 at a given constant speed in the
direction of arrow 14 while at the same time operating block 15 at such a second
speed as to move back and forth in the time taken by belt 8 to feed appendixes
26 one step forward, cord 5 may be fed on to branch 7 along a substantially sinusoidal
path defined by a series of straight cord portions 27 substantially parallel to
one another and to guide rod 18, and by two series of curved cord portions 28,
each looped about a respective appendix 26 and blending two adjacent straight
Portions 27 and 28 combine to define a reinforcing layer 29, which
is fed by conveyor 9 to a second conveyor 30 substantially coplanar with branch
7 of belt 8 and blending with conveyor 9 via a triangular plate 31 having a horizontal
upper surface 32 coplanar with branch 7, and a lower surface 33 sloping upwards
towards conveyor 30 and blending with surface 32.
Machine 1 also comprises an extrusion unit 34 consisting, in the
example shown, of two extruders 35 and 36 of variable shape, located respectively
over and beneath the end portion of conveyor 9 facing plate 31. According to a
variation not shown, and providing cord 5 is coated with uncured elastomeric material,
unit 34 may consist solely of upper extruder 35.
Extruders 35 and 36 are of the type described and claimed in USA
Patent n.4.744.745, the content of which is fully incorporated herein in the interest
of full disclosure, and are designed to produce respective layers 37 and 38 of
elastomeric material, each of which may be flat or of any shape varying transversely
in relation to the feed direction. In the Fig.5 and 7 example, layers 37 and 38
of body ply 2 present variable profiles, each having two thicker intermediate
longitudinal portions 39, whereas, on tread ply 3 in Fig.7, said layers, numbered
37a and 38a, are flat.
As shown in Fig.2, top layer 37 comes out of extruder 35 at substantially
the same speed as conveyor 9, and is fed, in the direction of arrow 40, towards
surface 32 of plate 31 over which a feed roller 41, mounted in idle manner on
a shaft 42 parallel to shafts 11 and 12, feeds layer 37 on to the upper surface
of reinforcing layer 29.
As shown also in Fig.2, bottom layer 38 comes out of extruder 36
at substantially the same speed as conveyor 9, and is fed, in the direction of
arrow 43, towards surface 33 of plate 31 beneath which two feed rollers 44 and
45, mounted in idle manner on respective shafts 46 and 47 parallel to shaft 42,
feed layer 38 first on to surface 33 and then on to the bottom surface of reinforcing
This completes the formation of body ply 2, which is then fed on
conveyor 30 through an optional cutting station 48 comprising two disc cutters
49 for cutting off respective lateral strips 50 of body ply 2 (Fig.1) and, if
so desired, removing curved portions 28 of cord 5 to obtain a body ply 2 of predetermined
width. If strips 50 are not removed, body ply 2 is of course formed initially
to a predetermined width.
From the foregoing description, machine 1 clearly provides for producing
simply and rapidly a continuous body ply 2 and/or tread ply 3 with no splices,
of any cross section, and having a reinforcing layer 29 formed from a single cord
5, thus eliminating the structural drawbacks mentioned previously.
According to a variation not shown, to increase the output speed
of reinforcing layer 29, two, three or a relatively limited number of cords 5 may
obviously be used, each being fed on to conveyor 9 by a respective distributing