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: FORMATION OF AN ENVELOPE PLY OF A TIRE
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian CEAT Ltd At: Get Muwala Po: Chandrapura Ta: Halol - 389 350 Dist: Panchmahal, Gujarat, 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 tire
manufacturing and, particularly but not exclusively, to a process of building a green tire.
BACKGROUND
[0002] Tire building materials that are generally used in the
manufacturing of a tire consist of an inner liner, one or more plies, sidewalls, bead rings, fillers, etc. All these tire building materials are combined to form a carcass assembly and one or more belts made of steel cord or other cord materials are combined with tread stock material to form a belt-tread stock assembly. These two assemblies are then combined to form a green tire, which is subsequently vulcanized in a mold.
[0003] To form the green tire, these tire building materials are
assembled and consolidated on a carcass building drum by wrapping the tire building materials around cylindrical circumferential margins of the carcass building drum. After wrapping all the required tire building materials, layer by layer, on the carcass building drum, the green tire is disintegrated from the carcass building drum and is sent for further processing, for example, vulcanization.
BRIEF DESCRIPTION OF DRAWINGS
[0004] 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.
[0005] Figure 1 illustrates a system for forming an envelope ply of a
tire, in accordance with an implementation of the present subject matter; and

[0006] Figure 2 describes a method of forming an envelope ply of a
tire, in accordance with an example implementation of the present subject matter.
DETAILED DESCRIPTION
[0007] In a tire, carcass strength is defined by tire cord fabric denier
and a number of carcass reinforcing plies used in the tire. Usually, tire
manufacturers use dual-layered carcass reinforcing ply as a carcass
reinforcement layer. However, using the dual-layered carcass reinforcing
plies increases the overall weight of the tire which may result in high
rolling resistance requiring more energy to move the tire forward.
[0008] A known alternative to using the dual-layered carcass
reinforcing ply involves using a single-layer carcass reinforcing ply also known as envelope ply, as the carcass reinforcement layer instead of the dual-layered carcass reinforcing ply. Thus, while reducing the overall weight of the tire, and simplifying the construction of the tire, the single carcass reinforcing ply structure provides the necessary support to the tire during both inflated and under-inflated operating conditions.
[0009] It has been found, however, that in a process of positing bead
rings over the envelope ply during the formation of a green tire, one or both edges of the envelope ply having extended width is lifted causing the envelope ply positions to shift unevenly. For example, the edges of the envelope ply may get lifted because of air released during carcass building drum expansion which tends to flow the air in the ply edges of the envelope ply causing the lifting phenomena. Such uneven shifting of the edges of the envelope ply may interfere with the positioning of subsequent tire building materials on the carcass building drum. This may lead to ply turnup height variation and nonuniformity in the final tire, thereby eventually increasing the quantity of scrap generated during the manufacturing of a tire.

[0010] Thus, the present subject matter provides a method and system
for forming an envelope ply that provides for avoiding ply folding issues during the formation of the green tire.
[0011] The method comprises positioning the envelope ply on an
expandable carcass building drum. The carcass building drum includes a cylindrical external circumference and is configured to support an envelope ply when loaded onto the cylindrical external circumference. Upon positioning, edges of the envelope ply extend beyond axial sides of the expandable carcass building drum and cover a length of two inflatable support members arranged on opposite axial sides of the expandable carcass building drum.
[0012] The method further comprises moving two pusher cans each
carrying a bead ring axially toward a bead-setting position and stopping moving when each of the two pusher cans reaches up to a predefined position away from the bead-setting position. Thereafter, the expandable carcass building drum is expanding such that an external diameter of the cylindrical external circumference of the expandable carcass building drum exceeds a diameter of a cylindrical outer surface of the two inflatable support members.
[0013] In an example implementation of the present subject matter,
after expanding the expandable carcass building drum, each of the bead rings is positioned on the envelope ply at the respective bead-setting position by axially moving each of the two pusher cans from the predefined position towards the bead-setting position.
[0014] By moving the pusher cans away from the edges of the
envelope ply towards the bead-setting position before expanding the expandable carcass building drum, folding the edges of the envelope ply may be avoided. Thus, by allowing selective axial movement of the pusher cans, the present subject matter facilitates setting up of the bead rings in the proper position without causing the folding of the envelope ply

edges, thereby reducing the possibility of the carcass generation due to uneven shifting of the edges of the envelope ply.
[0015] The above-mentioned implementations are further described
herein with reference to the accompanying figures. It should be noted that the description and figures relate to exemplary implementations and should not be construed as a limitation to the present subject matter. It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and embodiments of the present subject matter, as well as specific examples, are intended to encompass equivalents thereof.
[0016] Figure 1 illustrates a system 100 for forming an envelope ply
102 of a tire, in accordance with an implementation of the present subject matter. In an example implementation, the system 100 comprises an expandable carcass building drum 104. The expandable carcass building drum 104 has a cylindrical external circumference 106 onto which the envelope ply 102 is supported, as shown in Figure 1. In an example, the envelope ply 102 is a single layer carcass reinforcing ply.
[0017] The system 100 further comprises two inflatable support
members 108, 110 that are arranged on opposite axial sides 112, 114 of the expandable carcass building drum 104. As shown in Figure 1, edges 116, 118 of the envelope ply 102 extend beyond the axial sides 112, 114 of the expandable carcass building drum 104 and cover a substantial length of the two inflatable support members 108, 110.
[0018] The system 100 also comprises two pusher cans 120, 122. The
pusher cans 120, 122 are disposed adjacent to the respective inflatable support members 108, 110 and carry bead rings 124-1, 124-2. Each of the two pusher cans 120, 122 is movable axially of the expandable carcass building drum 104 and set respective bead rings 124-1, 124-2 in a bead-setting position 126.

[0019] The system 100 further comprises a control unit (not illustrated)
that is configured to move the two pusher cans 120, 122 axially, from their original position 128, toward the bead-setting position 126. The control unit stops the movement of the two pusher cans 120, 122 when each of the two pusher cans 120, 122 reaches up to a predefined position 130 away from the bead-setting position 126. In an example, the predefined position 130 may correspond to a position anywhere between the edges 116, 118 of the envelope ply 102 and the bead-setting position 126 and may be defined by a width of bead portion of the tire.
[0020] In an example embodiment of the present subject matter, the
pusher cans 120, 122 at the predefined position 130 are shown by a dotted line to illustrate a general orientation of the pusher cans 120, 122 at the predefined position 130 in relation to their original position 128. Once the pusher cans 120, 122 are stopped at the predefined position 130, the control unit causes the expandable carcass building drum 102 to expand in such a manner that a cylindrical outer surface 132, 134 of each of the two inflatable support members 108, 110 has a diameter that is less than an external diameter of the cylindrical external circumference 106 of the expandable carcass building drum 104.
[0021] After expanding the expandable carcass building drum 104, the
control unit axially moves each of the two pusher cans 120, 122 from the
predefined position 130 towards the bead-setting position 126 to position
bead rings 124 on the envelope ply 102 at the bead-setting position 126.
In the expanded state, the external diameter of the cylindrical external
circumference 106 of the expandable carcass building drum 104 is also
greater than a diameter of the bead ring 124 which prevents a forward
axial movement of the bead ring 124 from the bead-setting position 126.
[0022] In an example, a width of the envelope ply 102 may lie in a
range of 550 mm to 820 mm. In another example, a thickness of the envelope ply 102 lies in a range of 1.00 mm to 1.30 mm

[0023] During the formation of a green tire, first, the envelope ply 102
is loaded on the cylindrical external circumference 106 of the expandable
carcass building drum 104. Edges of the envelope ply 102 loaded on the
cylindrical external circumference 106 of the expandable carcass building
drum 104 extend beyond the axial sides 112, 114 of the expandable
carcass building drum 104, as shown in Figure 1. Thereafter, the two
pusher cans 120, 122 are brought from their original position 128 up to
the predefined position 130. At this stage, both the expandable carcass
building drum 104, as well as each of the two inflatable support members
108, 110, are in their original states, i.e., uninflated state. When the two
pusher cans 120, 122 are at the predefined position 130, the expandable
carcass building drum 104 is expanded so that the cylindrical outer
surface 132, 134 of each of the two inflatable support members 108, 110
has a diameter that is less than an external diameter of the cylindrical
external circumference 106 of the expandable carcass building drum 104.
[0024] Two parallel and spaced apart annular bead cores 136, 138
each located at the ends of the expandable carcass building drum 104 as shown in Figure 1 are formed at the bead-setting position 126 by the expansion of the expandable carcass building drum 104.
[0025] After expanding the expandable carcass building drum 104,
each of the two pusher cans 120, 122 is moved axially from the predefined position 130 towards the bead-setting position 126 to release the bead rings 124 in the bead cores 136, 138 on the envelope ply 102. Thereafter, the two pusher cans 120, 122 are retracted to their original position 128, and the inflatable support members 108, 110 are inflated to turn up the respective edges of the envelope ply 102 around the bead cores 136, 138.
[0026] In a conventional setup, axial movement of the pusher cans 120
122 towards the bead-setting position 126 is carried after the expansion of the expandable carcass building drum 104. Expansion of the expandable carcass building drum 104 prior to moving the pusher cans 120, 122

towards the bead-setting position 126 may cause lifting of the edges 116, 118 of the envelope ply 102. Such lifted edges tend to fold when they interface with pusher cans 120, 122 during movement of the pusher cans 120, 122 towards the bead-setting position 126.
[0027] In contrast to the conventional setup, in the present subject
matter, since in the uninflated state, the diameter of both the expandable carcass building drum 104, as well as each of the two inflatable support members 108, 110 is less than the diameter of the bead rings 124, by moving each of the two pusher cans 120, 122 up to the predefined distance 130 before expanding the expandable carcass building drum 104, the lifting of the edges 116, 118 of the envelope ply 102 may be avoided which usually happens when air is released during the expansion of the expandable carcass building drum 104 which tends to flow the air in the edges 116, 118 causing the lifting phenomena.
[0028] Once the pusher cans 120, 122 are moved towards the bead-
setting position 126 and brought up to a distance when are they no longer in the periphery of the edges 116, 118 of the envelope ply 102, even if the lifting of the edges 116, 118 occur, such lifting may not obstruct the movement of the pusher cans 120, 122.
[0029] As shown in Figure 1, the bead-setting position 126 lies in a
joint between the expandable carcass building drum 104 and the
inflatable support members 108, 110. In an example, the predefined
position 130 may lie 90-110 mm away from the bead-setting position 126.
[0030] In an example, the axial motion of the two pusher cans 120,
122 may be controlled by a servo motor or other mechanical means such as by levers or stepper motors (not illustrated) connected to each of the two pusher cans 120, 122 through the control unit. In another example, the control unit may be a programmable logic controller (PLC) that may be connected to a Human Machine Interface (HMI) unit (not illustrated). The HMI unit may be used by an operator of the system 100, to input/output data and monitor the system 100 and its operation. For example, the HMI

unit may be configured to provide position value settings to the control unit to control the axial movement of each of the two pusher cans 120, 122 by the servo motor with respect to the bead-setting position 126 on the envelope ply 102 that is arranged on expandable carcass building drum 104. The specific structure and operation of the HMI unit discussed above will be well understood by one skilled in the art. The detailed description of such known aspects of the HMI unit has been omitted herein.
[0031] Thus, by eliminating the folding issue during the envelope ply
construction, the present subject matter allows for the reduction in carcass scrap. Also, the envelope ply turnup height variation may be reduced to 3 mm from 5mm. In addition, uniformity yield is improved significantly, thereby reducing the changes due to air entrapment in the tire.
[0032] Figure 2 describes a method 200 of forming an envelope ply
102 of a tire, in accordance with an example implementation of the present subject matter. The order in which the method 200 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.
[0033] At block 202, the envelope ply 102 is placed on an expandable
carcass building drum 104 having a cylindrical external circumference 106. Upon positioning, edges 116, 118 of the envelope ply 102 extend beyond axial sides 112, 114 of the expandable carcass building drum 104 and cover a length of two inflatable support members 108, 110 that are arranged on opposite axial sides 112, 114 of the expandable carcass building drum 104.
[0034] At block 204, two pusher cans 120, 122 carrying a bead ring
124 are moved toward a bead-setting position 126 along axis of the expandable carcass building drum 104 and stopped when each of the two

pusher cans 120, 122 reaches up to a predefined position 130 away from the bead-setting position 126.
[0035] At block 206, the expandable carcass building drum 104 is
expanded such that an external diameter of the cylindrical external circumference 106 of the expandable carcass building drum 104 exceeds a diameter of a cylindrical outer surface 132, 134 of the two inflatable support members 108, 110.
[0036] At block 208, the bead ring 124 is positioned on the envelope
ply 102 at the bead-setting position 126 by axially moving each of the two pusher cans 120, 122 from the predefined position 130 towards the bead-setting position 126.
[0037] As would be understood, the methods and systems of forming
an envelope ply of a tire described in the present subject matter allow to develop the pusher cans forward and the expandable carcass building drum expansion sequence that may help avoid lifting and entangling of the envelope ply edges in the pusher cans. This reduces ply folding scrap, increases uniformity yield running average, and reduces the ply turnup height variation.
[0038] Although the subject matter has been described in considerable
detail with reference to certain examples and implementations thereof, other implementations are possible. As such, the present disclosure should not be limited to the description of the preferred examples and implementations contained therein.

I/We claim:
1. A method (200) of forming an envelope ply (102) of a tire,
comprising:
positioning (202) the envelope ply (102) on an expandable carcass building drum (104) having a cylindrical external circumference (106),
wherein, upon positioning, edges (116, 118) of the envelope ply (102) extend beyond axial sides (112, 114) of the expandable carcass building drum (104) and cover a length of two inflatable support members (108, 110) arranged on opposite axial sides (112, 114) of the expandable carcass building drum (104);
moving (204) two pusher cans (120, 122) carrying a bead ring (124) axially toward a bead-setting position (126) and stop moving when each of the two pusher cans (120, 122) reaches up to a predefined position (130) away from the bead-setting position (126);
expanding (206) the expandable carcass building drum (104) such that an external diameter of the cylindrical external circumference (106) of the expandable carcass building drum (104) exceeds a diameter of a cylindrical outer surface (132, 134) of the two inflatable support members (108, 110); and
positioning (208) the bead ring (124) on the envelope ply (102) at the bead-setting position (126) by axially moving each of the two pusher cans (120, 122) from the predefined position (130) towards the bead-setting position (126).
2. The method (200) as claimed in claim 1, wherein the predefined
position (130) corresponds to a position between the edges (116, 118) of the envelope ply (102) and the bead-setting position (126).
3. The method (200) as claimed in claim 1, wherein the predefined
position (130) lies in a range of 90-110 mm.

4. The method (200) as claimed in claim 1, wherein the envelope ply (102) is a single layer carcass reinforcing ply.
5. The method (200) as claimed in claim 1, wherein a width of the envelope ply (102) lies in a range of 550 mm to 820 mm.
6. The method (200) as claimed in claim 1, wherein a thickness of the envelope ply (102) lies in a range of 1 mm -1.3 mm.
7. A system (100) for forming an envelope ply (102) of a tire, comprising:
an expandable carcass building drum (104) having a cylindrical external circumference (106), the expandable carcass building drum (104) to support the envelope ply (102) when loaded on the cylindrical external circumference (106);
two inflatable support members (108, 110) arranged at opposite axial sides (112, 114) of the expandable carcass building drum (104),
wherein edges (116, 118) of the envelope ply (102) extend beyond the axial sides (112, 114) of the expandable carcass building drum (104) and cover a length of the two inflatable support members (108, 110);
two pusher cans (120, 122), wherein each of the two pusher cans (120, 122) is to carry a bead ring (124) and movable axially in a direction of a bead-setting position (126); and
a control unit to:
move the two pusher cans (120, 122) axially toward the bead- setting position (126) and stop when each of the two pusher cans
(120, 122) reaches up to a predefined position (130) away from the
bead-setting position (126);
expand the expandable carcass building drum (104) such
that an external diameter of the cylindrical external circumference (106)

of the expandable carcass building drum (104) exceeds a diameter of
a cylindrical outer surface (132, 134) of the two inflatable support
members (108, 110);
axially move each of the two pusher cans (120, 122) from
the predefined position (130) towards the bead-setting position (126) to
position the bead ring (124) on the envelope ply (102) at the bead-setting position (126).
8. The system (100) as claimed in claim 6, wherein the predefined position (130) corresponds to a position between the edges (116, 118) of the envelope ply (102) and the bead-setting position (126).
9. The system (100) as claimed in claim 6, wherein the predefined position (130) lies in a range of 90 - 110 mm.
10. The system (100) as claimed in claim 6, wherein the envelope ply (102) is a single layer carcass reinforcing ply.