FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13) 1. Title of the invention: CURING A GREEN TIRE
2. Applicants)

NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai - Maharashtra 400030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter relates, in general, to vehicle tires and,
particularly but not exclusively, to techniques of curing involved in manufacturing of tires.
BACKGROUND
[0002] Tires are a crucial component of an automobile. In an automobile, a tire
may be responsible for a plurality of functions. A tire may be required to conform to a plurality of industry and safety standards, owing to which, the steps involved in any tyre manufacturing process may be considered crucial. A plurality of different components may be designed and attached together to form a preliminary uncured tyre, which is referred to as green tire. The processed green tire, once obtained, may then be cured in a curing apparatus, as a final step for tire manufacturing process. During curing, the green tire may be subjected to high pressure in a mould, and heat may be applied, which in turn enables the chemical reactions between the rubber and other materials of the tire, and subsequently, the tire may be imprinted with tread pattern and side wall letter engraving.
BRIEF DESCRIPTION OF DRAWINGS
[0003] The detailed description is described with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the figure
in which the reference number first appears. The same numbers are used throughout
the drawings to reference like features and components.
[0004] Figure 1 illustrates a cross sectional view of a curing apparatus for curing
a green tire, in accordance with an implementation of the present subject matter.
[0005] Figure 2 illustrates a method for curing a green tire, in accordance with an
implementation of the present subject matter.
[0006] The figures are not necessarily to scale, and the size of some parts may be
exaggerated to more clearly illustrate the example shown. Moreover, the drawings

provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.
DETAILED DESCRIPTION
[0007] As would be generally understood, a tire is one of the most essential and
critical component of a vehicle. During vehicle operation, a tire is the only source of contact between the vehicle and the road, owing to which, a plurality of dynamics of the vehicle operation may be controlled by the tire. The tires may be responsible for guiding and maintaining the alignment and movement of a vehicle while driving. In addition, the tires contribute to the safety of the vehicle while carrying loads, and when the automobile is to be halted by application of brakes.
[0008] Owing to the complexity of roles performed by the tires in a vehicle, it may
be crucial for tire manufacturers to conform to quality parameters during any tire manufacturing process. Conventionally, rubber, along with other materials, may be used as a raw material for manufacturing the tires. A plurality of different components may be designed and assembled together, using a variety of techniques which involve both chemical and physical processes. For example, the raw materials may be processed into different components to form a toroidal shaped preliminary uncured tire, which is also referred to as a green tire.
[0009] Green tire, once obtained, may then be cured when subjected to a curing
processes in a curing apparatus. As would be understood, curing may refer to a process of applying pressure and heat energy to the green tire in a toroidal mould cavity in the curing apparatus. The heat energy thus applied enable chemical reactions between the rubber and other materials, to obtain its final shape. Thereafter, a tread pattern may be imprinted on the final manufactured tire.
[0010] The curing apparatus may include a toroidal mould cavity to accommodate
the green tyre. The internal walls of the toroidal mould cavity, may be equipped with an internal protruded pattern, corresponding to the required tread pattern on the final

manufactured tyre. A bladder is placed along the axis of the toroidal mould, for accommodating and circulating a volume of curing media. The curing media, conventionally, is steam at an elevated predefined temperature and pressure. The curing media may be circulated inside the curing bladder, to increase its temperature, and transfer the heat to the green tyre. As a result of circulation of curing media in the curing bladder, the curing bladder may get inflated, which may further result in the inflated bladder exerting a substantial amount of radially outward physical pressure on the green tyre, towards the internal walls of toroidal mould cavity of the curing apparatus. As a result of application of substantial amount of pressure on the green tyre from the inflated curing bladder towards the internal walls of the toroidal mould cavity, the green tyre gets pressed against the internal protruded tread pattern of the walls of the curing apparatus, and thereby, gets imprinted with tread pattern and side wall letter engraving. The heat energy provided by the curing media enables the chemical reactions between rubber and various other materials, thereby binding them, and enhancing the strength of the manufactured tyre.
[0011] Conventionally, steam is typically used to create the heat and pressure
needed for curing the green tire to get its final shape and tread pattern on its surface. Using steam in the curing process as a curing media to generate heat and to create a pressure on the green tire from the curing bladder, has several disadvantages. Production of steam energy involves high cost, since boilers required for the production of steam involves high cost of installation and maintenance. Operational cost of steam production is also high and steam energy is difficult to handle. Operational parameters for steam application to generate heat cannot be adjusted independently from one another. Further, maintenance efforts required for the steam production also lead to long downtimes. Moreover, equipment involved in the steam generation and transportation of steam to the curing apparatus and components of the curing apparatus get corroded rapidly and require maintenance frequently. As stated, such extensive maintenance efforts further lead to large downtime. Further, corrosion

resistant coatings and materials, such as additional antioxidants are needed to protect the bladder of the curing apparatus from premature deterioration. Such corrosion resistant materials are often expensive and not environment friendly. Also, condensing steam can lead to local overheating at the tire which may have a negative effect on quality of the tire produced and condensation issues in bladder which may cause structural damage to the bladder.
[0012] Some conventional techniques of curing a green tire employ induction
heating to cure the green tire. However, such techniques involve the use of steam as a curing media to create a pressure on the tire from the curing bladder. Thus, these techniques also suffer from the above described problems associated with the use of steam in the curing process. Moreover, curing apparatuses used in such techniques do not produce uniform heat at all contact points between the tyre and the curing bladder which may lead to poor quality of the tire manufactured.
[0013] To this end, the present subject matter provides techniques for curing a
green tire, the techniques overcome the above-described problems associated with the use of steam as a curing media to generate heat and create pressure for curing the green tire.
[0014] In accordance with an embodiment of the present subject matter, a curing
apparatus for curing a green tire is disclosed. The apparatus includes a mould assembly to accommodate the green tire and a heating assembly thermally coupled to the mould assembly. The heating assembly comprises a top platen and a bottom platen. A first set of induction coils is placed within the top platen and a second set of induction coils is placed within the bottom platen to produce heat for curing the green tire. The curing apparatus further comprises a curing bladder placed inside the mould assembly. The curing bladder accommodates a volume of a curing media. The curing media is nitrogen.
[0015] As evident, in the presently disclosed curing apparatus, heating of the
mould is done through the induction heating and pressure is created through nitrogen.

Thus, the use of induction heating and nitrogen as curing media obviates the use of steam energy for curing purposes. This further eliminates the problems associated with the use of steam energy in the curing process of the green tire. Since no boilers are required for steam production and less pipelines are required for transportation of curing media, manufacturing and operational cost is low in case of present curing apparatus. Further, since corrosion of pipelines used for supplying curing media and other components of the curing apparatus is eliminated owing to use of Nitrogen which is an inert gas, maintenance cost is also less.
[0016] Additionally, curing time involved is also less as compared to the
conventional curing process which uses steam for heating and pressurizing the green tire, since not only time involved in steam production is eliminated, but also less time is required for heat generation through induction heating. Moreover, the tire is heated at a uniform temperature at all points on its surface and also a uniform pressure is exerted on the tire during the curing process as compared to the conventional process utilizing steam as curing media. Also, the curing apparatus produces no CO2 emission in contrast to the conventional steam-based curing process.
[0017] The above and other features, aspects, and advantages of the subject matter
will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter along with examples described herein and, should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and examples thereof, are intended to encompass equivalents thereof. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components.

[0018] Figure 1 illustrates a cross sectional view of a curing apparatus 100 for
curing a green tire 102, in accordance with an implementation of the present subject matter.
[0019] In an implementation of the present subject matter, the curing apparatus
100 for curing the green tire 102 is disclosed. As described earlier, raw material
comprising rubber and other materials is used for manufacturing a tire. Different
components of a tire such as inner liner, sidewalls, body plies, beads, belt package are
assembled together using different techniques on a drum in a tire building machine.
The tire thus manufactured in an uncured state is called a green tire 102. The green tire
102 is cured in the curing apparatus 100 by applying heat and pressure. The curing
apparatus 100 comprises a mould assembly 104 to accommodate the green tire 102. In
an example, the mould assembly 104 may be of toroidal shape. The green tire 102 to
be subjected to curing may be placed inside such toroidal mould assembly 104.
[0020] The curing apparatus 100 further comprises a heating assembly 106. The
heating assembly 106 is thermally coupled to the mould assembly 104. The heating assembly 106 comprising a top platen 108 and a bottom platen 110. A first set of induction coils 112 is placed within the top platen 108 and a second set of induction coils 114 is placed within the bottom platen 116 to produce heat for curing the green tire 102. In an example, the mould assembly 104 is placed between the top platen 108 and the bottom platen 110 of the heating assembly 106. The first and second set of induction coils 112, 114 placed inside the top 108 and bottom 110 platen may be connected to a power source to draw an alternating current. The alternating current flowing through the induction coils 112, 114 generates a magnetic field between the top and bottom platen 108, 110. The mould assembly 104 placed between the top 108 and bottom 110 platen comes under the influence of this magnetic field. As a result, an eddy current is generated in closed loops in the mould assembly 104. The eddy current leads to the generation of heat inside the mould assembly 104 which heats the green tire 102 at a controllable and uniform temperature at all points. Heat applied to

the green tire 102 causes chemical reactions between the rubber and other materials and allows the tire to achieve a desired shape and strength.
[0021] The curing apparatus 100 further includes a curing bladder 116. The curing
bladder 116 is placed inside the mould assembly 104. The curing bladder 116 is configured to accommodate a volume of a curing media. The curing media may be nitrogen. In an example, curing bladder 116 may be vertically suspended along an axis of the mould assembly 104 and the bladder 116 may comprise an inlet passage to allow entry of the curing media into the curing bladder 116. The curing media may be supplied to the inlet passage through media supply pipes. The curing bladder 116 may further comprise an inner surface and an outer surface. The inner surface of the curing bladder 116 interfaces with the curing media, while the outer surface of the curing bladder 116 interfaces with the tire 102 to be cured. The curing media entered into the curing bladder 116 may be heated through the heating assembly 106. The nitrogen used as a curing media may be in a compressed state.
[0022] In an example implementation of the present subject matter, the heating
assembly 106 also comprises a casing 118 encapsulating the mould assembly 104. A third set of induction coils 120 may be placed within the casing 118, such that the third set of induction coils 120 is along a periphery of the mould assembly 104. The third set of induction coils 120 may also be connected to the power source to draw the alternating current. The alternating current flowing through the induction coils 120 generates a magnetic field inwardly from the casing 118. Since the mould assembly 104 is placed in this magnetic field, an eddy current is generated in the mould assembly 104 and flows in closed loop. The eddy current heats up the mould assembly 104 which in turn heats the green tire 102 accommodated therein.
[0023] In an example, the curing media may be circulated in the curing bladder
116 at an operational pressure. The circulation of curing media in the curing bladder 116 results in an inflated curing bladder 116. The inflated curing bladder 116 exerts a substantial amount of radially outward physical pressure on the green tire 102

accommodated in the mould assembly 104 towards internal walls of mould assembly 104. In an example, protruded tread pattern and optionally sidewall letters to be imprinted on the tire 102 may be formed on the internal walls of the mould assembly 104. The pressure exerted on the green tire 102 from the inflated curing bladder 116 towards the internal walls of the mould assembly 104, results in the green tire 102 get pressed against the internal protruded tread pattern on the internal walls of the mould assembly 104. As a result of which, the green tire 102 may get imprinted with the tread pattern and the side wall letter engraving. Thus, the pressure and heat applied to the green tire 102 enables the uncured green tire 102 to achieve a desired shape and strength of the tire along with a desired tread configuration.
[0024] Figure 2 illustrates a method 200 for curing a green tire 102, according to
an example of the present subject matter. The order in which the method is described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method 200, or an alternative method.
[0025] It may be understood that blocks of the method may be performed, for
example, by the above-described curing apparatus 100 for curing a green tire 102 as illustrated in Figure 1.
[0026] Referring to Figure 2, the method 200 starts at block 202. At block 202, the
green tire 102 is placed inside a mould assembly of a curing apparatus, such as the mould assembly 104 of the curing apparatus 100. As mentioned above, the green tire 102 may be produced by a tire building machine which assembles components of a tire onto a building drum and form various layers of the tire such as plies, beads and inner layer.
[0027] The method further proceeds to block 204. At block 204, a heating
assembly thermally coupled to the mould assembly is operated to generate curing heat in order to cure the green tire 102. The heating assembly may be the heating assembly 106 of the curing apparatus 100. The heating assembly 106 comprises a top platen 108

and a bottom platen 110. A first set of induction coils 112 is placed within the top
platen 108 and a second set of induction coils 114 is placed within the bottom platen
110 to produce heat for curing the green tire 102. As described above, the first and
second set of induction coils 112, 114 draw alternating current from a power source
which results in the generation of magnetic field between the top and bottom platen
108, 110. Placement of the mould assembly 104 between top and bottom platen 108,
110 in turn generates eddy current in the mould assembly 104 which heats up the
mould assembly 104 and consequently the green tire 102 accommodated therein.
[0028] At block 206, a volume of a curing media is circulated through a curing
bladder placed inside the mould assembly 104. The curing bladder may be the curing
bladder 116 of the curing apparatus 100. The curing media is nitrogen. The nitrogen
may be in a compressed state and gets heated inside the curing bladder 116. In an
example, the volume of the curing media may be circulated through the curing bladder
116 at an operational pressure. The circulation of the curing media results in an
expansion of the curing bladder 116. Expanded or inflated curing bladder 116 exerts
pressure on the green tire 102 and the green tire 102 is pressed towards inner walls of
the mould assembly 104. As a result of which, protruded tread pattern which may be
formed on the inner walls of the mould assembly 104 may get imprinted on the green
tire 102 and the tire may achieve its final shape along with tread pattern and strength.
[0029] As a result of an example implementation of the present subject matter, the
tire incorporated in a vehicle, when rolled over a road surface along the movement of the vehicle, in cabin noise and pass by noise are significantly reduced by 6 % and 5 % respectively as compared to the conventional tires. Further, because of reduced noise, less vibration are produced resulting in a more comfortable ride for the passengers which is improved approximately by 5 %. However, there is no impact on the wear appearance of the tire when compared with the conventional tire.
[0030] Although implementations of a curing apparatus 100 for curing a green tire
102 are described, it is to be understood that the present subject matter is not

necessarily limited to the specific features of the apparatus described herein. Rather, the specific features are disclosed as implementations for the curing apparatus 100 for curing the green tire 102.

I/We Claim:
1. A curing apparatus 100 for curing a green tire 102, the apparatus 100
comprising:
a mould assembly 104 to accommodate the green tire 102;
a heating assembly 106 thermally coupled to the mould assembly 104, the heating assembly 106 comprising a top platen 108 and a bottom platen 110, wherein a first set of induction coils 112 is placed within the top platen 108 and a second set of induction coils 114 is placed within the bottom platen 110 to produce heat for curing the green tire 102;
a curing bladder 116 placed inside the mould assembly 104, the curing bladder 116 is to accommodate a volume of a curing media, wherein the curing media is nitrogen.
2. The curing apparatus 100 as claimed in claim 1, wherein the heating assembly
106 also comprises:
a casing 118 encapsulating the mould assembly 104; and
a third set of induction coils 120 placed within the casing 118, such that the third set of induction coils 120 is along a periphery of the mould assembly 104.
3. The curing apparatus 100 as claimed in claim 1, wherein the curing media is circulated in the curing bladder 116 at an operational pressure.
4. A method 200 for curing a green tire 102, the method comprising:
placing 202 the green tire 102 inside a mould assembly 104 of a curing apparatus 100;
operating a heating assembly 106 thermally coupled to the mould assembly 104 to generate curing heat in order to cure the green tire 102, the heating assembly 106 comprising a top platen 108 and a bottom platen 110,

wherein a first set of induction coils 112 is placed within the top platen 108 and a second set of induction coils 114 is placed within the bottom platen 110 to produce heat for curing the green tire 102;
circulating a volume of curing media through a curing bladder 116 placed inside the mould assembly 104, wherein the curing media is nitrogen.
5. The method 200 as claimed in claim 4, wherein the method comprises
pressurizing the curing media to an operational pressure and wherein circulating the volume of the curing media comprises circulating the volume of the curing media through the curing bladder 116 at the operational pressure.