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: CALENDARING OF MATERIAL
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 calendaring process and,
particularly but not exclusively, to creating a sheet of predefined thickness from raw material through calendaring process for manufacturing tires.
BACKGROUND
[0002] Calendaring is a process of making a sheet of a predefined thickness from
a material. The material may be an elastomer or any fabric material. Through the process of calendaring, lamination or coating of a material may also be done on a sheet of other material. During the calendaring process, raw material is passed through plurality of pairs of rollers arranged spaced apart from each other vertically, horizontally or at an angle. Rollers are heated to a predefined temperature and moved at a predefined speed in a direction opposite to each other. Distance between two rollers in a pair depends on the required thickness of the sheet. During movement, rollers exert pressure on the material passed therethrough to compress the material to achieve the desired thickness and a smooth surface of the sheet.
[0003] It is desirable that a sheet of material produced through the calendaring has
an accurate thickness across the full length of the sheet. Further, surface of the sheet should be smooth. For example, if a sheet of rubber processed through the calendaring process is to be used in making a tire, the surface of the tire should be smooth. Otherwise, interaction of the tire with road surface and relative motion therebetween may lead to unbalancing of the tire movement resulting in inefficient performance of the vehicle.
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 schematic of a system for forming a sheet of a material
using a calendaring process, in accordance with an example implementation of the
present subject matter.
[0006] Figure 2 illustrates a temperature control unit used in the system for
forming the sheet of the material using the calendaring process, in accordance with an
example implementation of the present subject matter.
[0007] Figure 3 illustrates the calendaring process for forming a sheet of a
material, in accordance with an example implementation of the present subject matter.
DETAILED DESCRIPTION
[0008] The present subject matter relates to a calendaring process involved in the
process of manufacturing tires. As described above, calendaring is a process of preparing a continuous sheet of a material by passing the material through one or more pairs of counter rotating rollers or cylinders. Each of the rollers in a pair is arranged at a distance from the adjacent roller in accordance with the required thickness of the sheet to be produced. The rollers are heated to a predefined temperature during the calendaring process. Heated rollers cause the material to deform into the sheet of required thickness in a flexible manner.
[0009] However, speed of rotation of rollers increases the temperature of rollers
because of friction. Moreover, with the increase in speed of rotation of the rollers, temperature of the rollers further increases. Increase in the temperature of rollers beyond a predefined temperature, results in increase in temperature of the material passing therethrough. Rise in temperature of the material beyond a threshold limit may alter the properties of material and may affect the quality of the sheet to be produced. For example, air blisters may be formed on a surface of the sheet because of high temperature of the material.
[0010] Further, if the temperature of the material being calendered, such as an
elastomer or rubber is high, the material may stick to the rollers, which in turn results in rough surface of the sheet. Sticking of the material to the rollers not only creates

obstacles in the movement of the rollers, at high temperature of the material, quantity of scrap produced during the calendaring process is also high. Further, owing to the high temperature, thickness of the sheet may also vary along the length of the sheet because of non-uniform deformation of the material having high temperature under the pressure of rollers.
[0011] Thus, in the existing techniques related to calendaring process, speed of the
rollers cannot be increased beyond a predefined speed limit. This impedes the efficiency of the calendaring process. The speed limit may be different for different materials. For instance, if the material is an elastomer, such as rubber, increasing the speed of the rollers beyond 30 mpm may increase the temperature of the elastomer beyond 105 °C which causes the elastomer to stick on the rollers resulting in a poor quality of the sheet and large scrap generation.
[0012] To this end, the present subject matter provides a technique to overcome
the above-described problem associated with a calendaring process of forming a sheet of a material. The technique described in the present subject matter improves the efficiency of the calendaring process without affecting a quality of the sheet produced by controlling the temperature of the rollers during the calendaring process. Thus, overall productivity of the tire manufacturing process may be enhanced.
[0013] In accordance with an embodiment of the present subject matter, a
calendaring process of forming a sheet of a material is disclosed. In an example, the sheet may be a rubber-fabric or rubber-metal ply used for manufacturing a tire. The rubber of required thickness may be coated on a fabric or metal such as steel and a layered rubber-fabric/metal-rubber sheet can be produced through the calendaring process.
[0014] According to the process, a plurality of rollers are operated at a speed not
exceeding a first speed to pass the material therethrough. The material may be an elastomer or polymer or metal or any other material that can be used in the production of a fabric. Further, a temperature of the plurality of rollers operating at the speed not

exceeding the first speed is maintained at a first temperature setting. When the material is passed through the plurality of rollers, pressure is exerted by the rollers heated according to first temperature setting on the material to deform the material into a sheet of required thickness and heat is also transferred to the material from the rollers and because of friction between the rotating rollers. Temperature of the material passing through the rollers is monitored. If the temperature of the material exceeds a predetermined threshold value, the temperature of the plurality of rollers is changed to a second temperature setting and is maintained at the same. The temperature of the plurality of rollers in the second temperature setting is lower than the temperature of the plurality of rollers in the first temperature setting. Further, if the temperature of the plurality of rollers corresponds to the second temperature setting, the plurality of rollers are operated at a speed greater than the first speed and not exceeding a second speed.
[0015] According to the present technique of calendaring the material, the
temperature of the rollers is kept high at the starting of the calendaring process to produce sufficient heat to avoid processing issues. For instance, warming time may be high at low temperature and start up scrap generation may also be high. When temperature of the material exceeds a predetermined threshold value, the temperature of the rollers is lowered according to the predefined temperatures settings. This enables controlling the temperature of the material from exceeding a predefined threshold value. Since the temperature of material is controlled, the rollers can be operated at a high speed without causing the temperature of the material exceeding the threshold value. Thus, more material can be processed through the calendaring process in a given period of time, thereby enhancing the efficiency of the calendaring process. Further, quality of the sheet produced is also high, as the problem of sticking of the material at the surface of the rollers because of high temperature of the material at high speed of the rollers is obviated.

[0016] 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.
[0017] Figures 1 illustrates a schematic of a system for forming a sheet of a
material using a calendaring process, in accordance with an implementation of the present subject matter. Figure 2 illustrates a temperature control unit used in the system for forming the sheet of the material using the calendaring process, in accordance with an implementation of the present subject matter. For the sake of ease of explanation Figure 1 and Figure 2 are explained in conjunction with each other.
[0018] Referring to Figure 1, a system 100 for forming a sheet 102 of a material
104 using a calendaring process is described, in accordance with an implementation of the present subject matter. As described above, calendaring process is used to form a sheet 102 of a material 104 of required thickness or coating a material 104 of required thickness onto another material. The material 104 may an elastomer or a polymeric material or a material that can be used in a fabric. An elastomer or rubber can be used in making a sheet 102 of rubber or rubber-fabric or rubber-metal ply to be used in manufacturing a tire. Also, the material 104 may be a material used in making a fabric or a polymeric sheet.
[0019] The system comprises a plurality of rollers or cylinders 106. The plurality
of rollers 106 may be arranged in a particular configuration, for example, vertically,

horizontally, inclined at an angle, in L-shape, in S-shape, in Z-shape or the like. A distance between two adjacent rollers 106 depends on the required thickness of the sheet 102 to be produced. In an example implementation depicted in Figure 1, four rollers 106 are arranged in S-shape.
[0020] The system 100 also comprises a temperature control unit (TCU) 114 to
control or maintain the temperature of the plurality of rollers 106 during the calendaring process. Figure 2 shows the temperature control unit (TCU) 114, according to an example implementation of the present subject matter. In an example, the TCU 114 may further include processor(s) 106 which may be in communication with other devices such as a speed sensor 108 and a temperature sensor 116 as depicted in Figure 1 and described later. The processor(s) 202 may be implemented as microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and/or any devices that manipulate signals based on operational instructions. Among other capabilities, the processor(s) 202 is configured to fetch and execute computer-readable instructions stored in a memory, for example, in order to control and maintain the temperature of the plurality of rollers. In another example, the processor(s) 202 is to operate the plurality of rollers 106 within various speed limits.
[0021] The TCU 114 may further include interface(s) 204. The interface(s) 204
may include a variety of software and hardware interfaces that allow the connection
or coupling of the TCU 114 with one or more other devices, through a wired (e.g.,
LAN) connection or through a wireless connection (e.g., Bluetooth®, WiFi). For
example, the interface(s) 204 may couple the TCU 114 with the speed sensor 108 or
the temperature sensor 116. The interface(s) 204 may also enable intercommunication
between different logical as well as hardware components of the TCU 114.
[0022] Further, the TCU 114 comprises a memory 206 coupled to the processor
202. The memory 206 may be implemented as a computer-readable medium known in the art including, for example, volatile memory (e.g., RAM), and/or non-volatile

memory (e.g., EPROM, flash memory, etc.). The memory 206 may also be an external memory unit, such as a flash drive, a compact disk drive, an external hard disk drive, or the like. The memory 206 may include data which is either utilized and/or is generated during the calendaring process or the operation of the TCU 114. In one example, the memory 206 may include information or values of configuration settings pertaining to the TCU 114. For example, the memory 206 may include a first temperature setting 208, a second temperature setting 210, a speed data 212, a temperature sensor data 214 and other data 216. The first temperature setting 208, and the second temperature settings 210 specifies temperature ranges for heating the plurality of rollers 106 during the calendaring process. Further, the speed data 212 specifies the first speed and the second speed at which the plurality of rollers 106 can be operated during the calendaring process. The temperature sensor data 214 refers to the data generated and captured from the temperature sensor 116 during the calendaring process.
[0023] In operation, the plurality of rollers 106 are rotated at a speed not exceeding
a first speed. In an example, the first speed is in the range 26 meters per minute (Mpm)
to 40 Mpm. Every two adjacent rollers from amongst the plurality of rollers 106 are
rotated a direction opposite to each other. The system 100 further comprises a speed
sensor 108 to monitor the speed of rollers 106. The material 104 such as rubber is fed
to the rollers 106 form a side of a pair of rollers and is passed subsequently to each
pair of counter rotating rollers 106. In an example, a sheet of rubber-fabric or rubber-
metal to be used in manufacturing of a tire is to be formed through the calendaring
process. For this purpose, rubber is fed separately through two separate pair of rollers
106 and a fabric or metal 110 guided through a guide roller 112 is passed through a
pair of rollers arranged between the pairs of rollers used for feeding the rubber such
that a layer of the metal or fabric 110 is sandwiched between two layers of rubber 104.
[0024] Initially, the plurality of rollers 106 are heated at a high temperature in
accordance with the first temperature setting 208 as specified by the TCU 114, since

processing issues such as high warming time or start up scrap generation can be avoided if the rollers 106 a re initially heated to a h igh temperature . In an example, the temperature of the plurality of rollers in the first te mperature setting is in the range of
70°C to 80 °C.
[0025] When the material 104 passes through the plurality of heated and counter-
rotating rollers 106, the rollers 106 exert pressure on the material 104 passing therethrough and deforms and compresses the material 104 to produce the sheet 102 of required thickness. As the process progresses, heated rollers 106 transfers heat to the material 104 passing therethrough and speed of the rollers 106 also causes the temperature of the material 104 to increase because of friction. The system 100 comprises the temperature sensor 116 to monitor temperature of the material 104 passing through the rollers 106. The TCU 114 receives the data pertaining to the temperature of the material 104 . Wh e n the te mperature se nsor 114 determines that th e temperature of the material 104 exceeds a predetermined threshold value, the TCU 114 changes the temperature of the rollers 106 in accordance with the second temperature setting 210 and maintains the tempe rature of th e plurality
second temperature setting. The predetermined threshold value may be stored in the memory 206 of the TCU 114. The threshold value of the temperature of the material 104 varies for different materials depending on the properties of the respective material. For example, in case of rubber the threshold value may be 105 ℃. Further, the temperature of the plurality of rollers 106 in the second temperature setting 210 is lower than the temperature of the plurality of rollers 106 in the first temperature setting 208. In an e xa mpl e, th e te mperature of the plurality of rollers in the sec ond te mperature setting is in the range of 60°C to 70 °C
[0026] If the temperature of the rollers 106 c orresponds to the second temperature
setting 210, the plurality of rollers 106 are operated at a speed greater than the first speed and not exceeding the second speed. In an example, the second speed is in the range 33 Mpm to 45 Mpm. This increase in speed of the rollers 106 does not increase

the temperature of the material 104 beyond the threshold value, since the temperature of the rollers 106 is maintained by the TCU 114 at the second temperature setting 210 in which temperature of the rollers 106 is less than the first temperature setting 208. Thus, such alternation between two temperature settings 208, 210 allow to operate the rollers 106 at high speed without giving rise to the adverse effects that would otherwise be produced because of the high temperature of the material 104. This increases the productivity of the calendaring process and produces a sheet of high quality. For example, the rubber-fabric sheet as produced though the process for manufacturing the tire does not include blisters on the surface of the sheet 102.
[0027] Figure 3 illustrates a calendaring process 300 for forming a sheet of a
material, according to an example of the present subject matter. The order in which the process is described is not intended to be construed as a limitation, and any number of the described process blocks may be combined in any order to implement the process 300, or an alternative process.
[0028] It may be understood that blocks of the process may be performed, for
example, by the above-described system for forming a sheet of a material using a calendaring process as illustrated in Figure 1.
[0029] Referring to Figure 3, the process 300 starts at block 302. At block 302, a
plurality of rollers such as the rollers 106 of system 100 are operated at a speed not exceeding a first speed to pass the material therethrough. Each roller in a pair of adjacent rollers from amongst the plurality of rollers is rotated in a direction opposite to each other.
[0030] At block 304, at the starting of the process, the temperature of the plurality
of rollers operating at the speed less than the first speed is maintained at a first temperature setting by a temperature control unit such as the TCU 114. The first temperature setting may be stored in the memory 206 of the TCU 114.
[0031] Temperature of the material passing through the plurality of heated and
rotating rollers increases because of friction and heat transfer from the rollers to the

material. At block 306, temperature of the material is monitored through a temperature
sensor, such as the temperature sensor 116 of the system 100.
[0032] At block 308, the temperature of the material is compared by a processor
such as the processor 202 of the TCU 114 against a threshold value. The threshold
value may be stored in the memory of the TCU 114.
[0033] If it is determined that the temperature of the material exceeds the
predetermined threshold value, the process proceeds to block 310, otherwise the
process proceeds to blocks 302. At block 310, the temperature of the plurality of rollers
is changed be the TCU 114, according to a second temperature setting and is
maintained at the second temperature setting. The second temperature setting may be
stored in the memory of the TCU 114. The temperature of the plurality of rollers in
the second temperature setting is lower than the temperature of the plurality of rollers
in the first temperature setting.
[0034] At block 312, if the temperature of the plurality of rollers corresponds to
the second temperature setting, the plurality of rollers are operated at a speed greater
than the first speed and not exceeding a second speed. The temperature of the material
is not increased with this increase in speed, since temperature of rollers is lowered and
operating the rollers at high speed increases the productivity of the calendaring
process.
[0035] Although implementations of a calendaring process are described, it is to
be understood that the present subject matter is not necessarily limited to the specific
features of the process described herein. Rather, the specific features are disclosed as
implementations for the calendaring process.

I/We Claim:
1. A calendaring process 300 of forming a sheet 102 of a material 104, the process
300 comprising:
operating 302 a plurality of rollers 106 at a speed not exceeding a first speed to pass the material 104 therethrough;
maintaining 304 a temperature of the plurality of rollers 106 operating at the speed not exceeding the first speed at a first temperature setting 208;
monitoring 306 a temperature of the material 104 passing through the plurality of rollers 106;
if the temperature of the material 104 exceeds a predetermined threshold value, maintaining 308 the temperature of the plurality of rollers 108 at a second temperature setting 210; and
if the temperature of the plurality of rollers 106 corresponds to the second temperature setting 210, operating the plurality of rollers 106 at a speed greater than the first speed and not exceeding a second speed,
wherein the temperature of the plurality of rollers 106 in the second temperature setting 210 is lower than the temperature of the plurality of rollers 106 in the first temperature setting 208.
2. The process 300 as claimed in claim 1, wherein the process comprising rotating two adjacent rollers from amongst the plurality of rollers 106 in opposite direction of each other.
3. The process 300 as claimed in claim 1, wherein the first speed is in the range of 26 meters per minute (Mpm) to 40 Mpm.
4. The process as claimed in claim 1, wherein the second speed is in the range of 33 Mpm to 45 Mpm.

5. The process as claimed in claim 1, wherein the te mperature of the plurality of rollers in the f irst te mperature setting is in the range of 70℃ to 80 ℃.
6. The process as claimed in claim 1, wherein the te mperature of the plurality of rollers in the second temperature setting is in the range of 60℃ to 70 ℃.
7. A system 100 for forming a sheet 102 of a material 104 using calendaring process, the system comprising:
a plurality of rollers 106 operating to allow the material to pass therethrough;
a temperature control unit 114 c oupled to the plurality of rollers and;
a temperature sensor 116 to monitor temperature of the material 104 and coupled to the temperature control unit 114;
the temperature control unit is to:
operate the plurality of r o ll ers 106 at a spee d not exceeding a first speed;
maintain a temperature of the plurality of rollers 106 operating at the speed not exceeding the first s pee d at a f irst te mperature setting 208;
if the temperature of the material 104 monitored by the temperature sensor exceeds a pre d eter mi ne d threshol d value, maintain the temperature of the plurality of rollers 108 at a second temperature setting 210; and
if the temperature of the plurality of rollers 106 corresponds to the second temperature setting 210, operate the plurality of ro ll ers 106 at a spee d greater than the first speed and not exceeding a second speed,
wherein the temperature of the plurality of rollers 106 in the second temperature setting 210 is lower than the temperature of the plurality of rollers 106 in the first temperature setting 208.

8. The system 100 as claimed in claim 7, wherein the first speed is in the range of 26 meters per minute (Mpm) to 40 Mpm , and the second speed is in the range of 33 Mpm to 45 Mpm.
9. The system 100 as claimed in claim 7 , where in the temperature of the plura li ty of rollers in the first te m perature setting is in the range of 70°C to 80 °C.
10. The system 100 as claimed in claim 7 , where in the temperature of the plura li ty of rollers in the sec ond te mperature setting is in the range of 60°C to 70 °C.