Claims:1. A tire building drum machine (121), for reducing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, comprising of : a flat drum assembly (130), having a first outer drum (122) and a second outer drum (123), said first outer drum and the second outer drum is spaced apart; a inflating unit (124), said inflating unit positioned in-between the said first outer drum (122) and the said second outer drum (123), wherein said inflating unit inflates the plurality of tire plies forming a green tire (129); a pair of bead lock bladder (125a,125b), each placed at the either ends of the said inflating unit (124), each of the said bead lock bladder (125a,125b) are in contact with one end of the said first outer drum (122) and the said second outer drum (123); a pair of outer flange (126a,126b), each positioned at the outer end of the said first outer drum (122) and the said second outer drum (123); a plurality of turn up arms, having a first set of plurality of turn up arms (127a) and a second set of plurality of turn up arms (127b), wherein said first set of plurality of turn up arms (127a) are assembled on the said first outer drum (122), wherein said second set of plurality of turn up arms (127b) are assembled on the said second outer drum (123); and a plurality of turn up rollers (128), position on the said plurality of turn up arms (127a, 127b), wherein said each of the turn up arm is provided with atleast a turn up roller (128)
characterized in that, the said first set of plurality of turn up arms (127a) with turn up rollers (128) glides over the first side of the green tire (129a) positioned on the said inflating unit (124) at a predefined axial deviation from the axis of the said first outer drum (122), wherein said second plurality of turn up arms (127b) with turn up rollers (128) glides over the second side of the green tire (129b) positioned on the said inflating unit at a predefined axial deviation from the axis of the second outer drum (123), wherein the said turn up rollers (128) are provided with specific roller profile.
2. The tire building drum machine (121), according to claim 1, wherein said axial deviation of the first set of plurality of roller arms (127a) from the axis of the said first outer drum (122) ranges from 0.1° to 45°.
3. The tire building drum machine (121), according to claim 1, wherein said axial deviation of the second set of plurality of roller arms (127b) from the axis of the said second outer drum (122) ranges from 0.1° to 45°.
4. The tire building drum machine (121), according to claim 1, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in clockwise direction.
5. The tire building drum machine (121), according to claim 1, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in counter clockwise direction.
6. The tire building drum machine (121), according to claim 1, claim 4 and claim 5, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in identical direction.

7. The tire building drum machine (121), according to claim 1, claim 4 and claim 5, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in opposite direction.
8. The tire building drum machine (121), according to claim 1, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in forward/ head stock direction.
9. The tire building drum machine (121), according to claim 1, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in reverse/ tail stock direction.
10. The tire building drum machine (121), according to claim 1, wherein said plurality of turn up rollers (128) on the turn up arm (127a,127b) are positioned in tandem.
11. The tire building drum machine (121), according to claim 1, wherein said profile of the said turn up roller (128) is selected from but not limited to circular, conical, spherical, hemispherical, elliptical, cylindrical and/or combinations thereof.
12. A tire building process, with reduced/ eliminated sidewall undulation effect on the inflated pneumatic tire, comprising steps of : placing first tire components including a plurality of tire plies, a sidewall and a inner liner on the flat drum assembly (130); placing second tire components on the first tire components, said second tire components includes a carcass and a plurality of plies of plurality of beads; inflating the first tire components and the second tire components by means of an inflating unit (124); stitching the first tire components and the second tire components to form the green tire (129); gliding a first set of plurality of turn up arms (127a) with turn up rollers (128) and a second set of plurality of turn up arms (127b) with turn up rollers (128), over the green tire (129) to turn over the excessive first tire components; retracting the first set of plurality of turn up arms (127a) with turn up rollers (128) and a second set of plurality of turn up arms (127b) with turn up rollers (128) back to the initial position; and removing the complete assembled green tire (129) from the said flat drum assembly (130),
characterized in that, said gliding of first set of plurality of turn up arms (127a) with turn up rollers (128) is axially deviated from the axis of the said first outer drum (122) at a predefined angle, wherein said gliding of second set of plurality of turn up arms (127b) with turn up rollers (128) is axially deviated from the axis of the said second outer drum (123) at a predefined angle, thereby the said plurality of turn up arms (127a, 127b) with turn up rollers (128) during the turn up operation of the excess plies are positioned in an axially deviated path inclined to the direction of the cord path.
13. The tire building process, according to claim 11, wherein said axial deviation of the first set of plurality of roller arms (127a) from the axis of the said first outer drum (122) ranges from 0.1° to 45°.
14. The tire building process, according to claim 11, wherein said axial deviation of the second set of plurality of roller arms (127b) from the axis of the said second outer drum (122) ranges from 0.1° to 45°.
15. The tire building process, according to claim 11, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in clockwise direction.
16. The tire building process, according to claim 11, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in counter clockwise direction.
17. The tire building process, according to claim 11, claim 15 and claim 16, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in identical direction.

18. The tire building process, according to claim 11, claim 15 and claim 16, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in opposite direction.
19. The tire building process, according to claim 11, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in forward/ head stock direction.
20. The tire building process, according to claim 11, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) and the said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in reverse/ tail stock direction.
, Description:AN IMPROVED DRUM MACHINE FOR REDUCING THE TIRE SIDEWALL UNDULATION AND PROCESS THEREOF
FIELD OF THE INVENTION
The present invention relates to a tire building process, more specifically the present invention relates to the sidewall tread assembling method of the tire building process and a drum machine thereof, for reducing/eliminating the undulation defect on the pneumatic tire.
BACKGROUND OF THE INVENTION
Tire is a highly engineered structural composite, generally made of rubber and rubberised stiffeners, to envelop the wheel rim and provide traction between the vehicle and the road, it also absorbs the shock by providing a cushioning effect. A conventional tire comprises of 10 or more components including rubber compounds assembled into several parts such as tread, bead, sidewall, shoulder, and ply. In general tire manufacturing process is a five step process comprising of: compound preparation, where raw materials are pre-processed; component preparation, includes calendaring of rubber sheets, bead bundle preparation and extrusion; tire building/assembly process, where all components are assembled over the drum; curing, involves vulcanization of the green tire into a strong, elastic finished product, called the cured tire; and final inspection of the cured tire. Uniformity is one of the most vital parameter that affects the tire performance. Non-uniformity in the tire structure may cause fluctuations, static imbalance, coupling imbalance and also often affects the aesthetics of the tire.
Conventional tire building drum machine (Step 3 of the tyre manufacturing process) involves the assembly of tire components including the inner liner, carcass plies, sidewalls, sidewall reinforcing members and bead bundle on a cylindrical former, known as tire building drum. In parallel on another drum the other tire components such as tread line, belt plies etc are assembled. After this arrangement, the said two tire components are arranged on another station in which carcass plies are inflated into a donut shape of a desired level and the edge portions of the carcass ply are turned around their respective bead wires towards and on to the central portion of the fabric by means of swivelling arms on which rollers are fixed for a smooth turn up operation. This results in a green/un-vulcanized tire, which further requires curing and finishing to become the final end product.
During the turn up/folding process, the arms and the rollers stretches and exerts force on the side wall of the green/unvulcanized tire. Due to the force exerted, the ply material of the sidewall comprising many steel cords gets displaced. The displacement of the steel cords produces the undulation/indentations on the sidewall of the inflated pneumatic/vulcanised tire. This undulations/indentations severely affects the uniformity as well as the aesthetics of the tire These sidewall indentations/undulations are more prominent in tires with larger sidewalls or tires which operate at higher inflation pressures. Fortunately these sidewall indentations are only cosmetic condition and does not adversely affect the performance or safety of the tires. Even though the sidewall undulations/indentations do not affect the tyre performance but creates a huge impact as a quality parameter during the consumer/market acceptance. Current competitive market puts forward greater challenges not only in terms of tire performance but also in terms of tire uniformity and aesthetics. Therefore there exists a need in the art for elimination of this sidewall undulation/indentations in the pneumatic tyres to increase the tyre aesthetics and consumer acceptance.
EP223317 relates to an apparatus used for pressing the belt/tread assembly and the carcass with the beads and the side walls is realized by a pressure roller unit with a static pressing roller with at least one roller or group of coaxial rollers radially movable through the gate in the passage part. The apparatus comprises a transfer unit which stays in place around the carcass drum during pressing, so that a relatively short period is required for the manufacture of a green radial tire.
US patent application No. 61004291 describes about the tyre building drum comprising a folding arms with a roller element and steering element, wherein the roller element presses the outer part of the tyre components against a bead ring core to be placed on the bead ring segment while simultaneously the roller element moves away from the longitudinal axis, wherein the steering element moves along the steering surface until the stop of the annular steering segment abuts an annular folding arm segment, after which the folding arm swivels about a swivel axle and the steering element comes to lie apart from the steering surface. This document does not describe the distribution of forces exerted by the roller elements on the steel cords of the tyre sidewall. Thus the forces exerted by the roller elements on the sidewall will produce undulation on the sidewall of the inflated pneumatic tyre.
US patent application No. 13/508915 relates to a device for turning up a tyre-building part on a tyre-building drum using a roller lever, on which at least one rotatably mounted crimping roller is arranged, wherein the roller lever turns up the tyre component in a radial direction on a tyre blank, and the tyre component is thereby folded over and joined to the tyre blank. The crimping roller is spaced in such a way that the crimping roller is substantially exclusively in contact with the tyre-building part and the roller rolls along the tyre-building part. This document describes about the usage of two rollers (roller and crimping roller) on each roller arm, therefore more force is exerted on the sidewall and thus displace the steel cords of the sidewall. Due to this displacement of the steel cords, sidewall of the inflated pneumatic tyre is undulated.
The above cited prior-art documents describes different types of rollers and rolling mechanisms available for efficient turning up of the extra carcass ply on the tyre building drum. But none of the documents addresses the problem of sidewall undulation/indentations caused due to the stress and pressure exerted by the arms and rollers on the carcass ply. Therefore there is need in art to address the aforementioned shortcomings in the tire building machine and the process. The present invention provides a simple and efficient method of reducing/eliminating the sidewall undulations/indentation in the pneumatic tires by providing an improved tyre building drum machine with rollers positioned in an axially deviated path inclined to the direction of cord path. This during the folding/turn-up process of the carcass ply, distributes the force exerted by the rollers across the steel cords keeping them intact and prevents them from getting displaced or overlapped, thereby minimizing/eliminating the sidewall undulation/indentations.
OBJECTIVE OF THE INVENTION
The primary objective of the present invention is to minimize/eliminate the sidewall undulation/indentations caused during the tire building process, thereby increasing the tire uniformity, aesthetics and consumer acceptance.
Another objective of the present invention is to provide a tire building machine with rollers moving in an axially deviated path inclined to the direction of the cord path during the turn up process of the carcass ply, which reduces/eliminates the undulation effect on the sidewall of the inflated pneumatic tire.
Still another objective of the present invention is to provide a mechanism during turn-up process which distributes the force exerted by the rollers across the steel cords keeping them intact and preventing them from getting displaced or overlapped, thereby eliminating the sidewall undulation/indentations.
SUMMARY OF THE INVENTION
A tire building drum machine (121) according to the present invention used for minimizing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, comprises of : a flat drum assembly (130); a inflating unit (124); a pair of bead lock bladder (125a,125b); a pair of outer flange (126a,126b); a plurality of turn up arms(127a,127b); and a plurality of turn up rollers (128). The said turn up arms (127a,127b) with turn up rollers (128) of the said tire building machine (121) are positioned in an axially deviated path inclined to the direction of cord path. The said deviation during the turn-up/folding process of the excess tire carcass plies distributes the force exerted by the said turn up rollers (128) across the steel cords keeping them intact and preventing them from getting displaced or overlapped, thereby eliminating the sidewall undulation/indentations. The said turn up rollers (128) of the present invention are precisely profiled which enhances the reduction rate of the undulation on the tire sidewall. This increases the uniformity, aesthetics and consumer acceptance of the pneumatic tires. Further the present invention provides a simple and efficient method of tire building process which reduces/eliminates the sidewall undulations/indentation in the pneumatic tires by using the said tyre building machine (121) with precisely profiled turn up rollers (128) positioned in an axially deviated path inclined to the direction of cord path. This improved method of tire tread assembly maintains the deformation of sidewall tread of the tire at the desired level and improves the tire tread profile retention.
BRIEF DESCRIPTION OF THE DIAGRAM
Figure 1 shows the perspective view of the tire building drum machine according to the present invention.
Figure 2 represents the tire building drum machine of the present invention with green tire showing the folding/turn up process.
Figure 3a shows the regular turn up roller path (131) on the green tire as seen in the existing prior-art.
Figure 3b shows the deviated turn up roller path (132) on the green tire according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention as embodied by the " Drum machine for reducing the tire sidewall undulation and process thereof," succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The present invention provides a tire building drum machine (121), for reducing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, comprising of : a flat drum assembly (130), having a first outer drum (122) and a second outer drum (123), said first outer drum and the second outer drum is spaced apart; an inflating unit (124), said inflating unit is positioned in-between the said first outer drum (122) and the said second outer drum (123); a pair of bead lock bladder (125a,125b), each placed at the either ends of the said inflating unit (124), each of the said bead lock bladder (125a,125b) are in contact with one end of the said first outer drum (122) and the said second outer drum (123); a pair of outer flange (126a,126b), each positioned at the outer end of the said first outer drum (122) and the said second outer drum (123); a plurality of turn up arms, having a first set of plurality of turn up arms (127a) and a second set of plurality of turn up arms (127b), wherein said first set of plurality of turn up arms (127a) are assembled on the said first outer drum (122), wherein said second set of plurality of turn up arms (127b) are assembled on the said second outer drum (123); and a plurality of turn up rollers (128), position on the said plurality of turn up arms (127a, 127b), wherein said each of the turn up arm is provided with atleast a turn up roller (128),
Characterized in that, the said first set of plurality of turn up arms (127a) with turn up rollers (128) glides over the first side of the green tire (129a) positioned on the said inflating unit (124) at a predefined axial deviation from the axis of the said first outer drum (122), wherein said second plurality of turn up arms (127b) with turn up rollers (128) glides over the second side of the green tire (129b) positioned on the said inflating unit at a predefined axial deviation from the axis of the second outer drum (123), wherein the said turn up rollers (128) are provided with specific roller profiles.
In an embodiment of the present invention, the tire building process, for reducing/ eliminating sidewall undulation effect on the inflated pneumatic tire, comprises steps of : placing first tire components including a plurality of tire plies, a sidewall and a inner liner on the flat drum assembly (130); placing second tire components on the first tire components, said second tire components includes a carcass and a plurality of plies of plurality of beads; inflating the first tire components and the second tire components by means of an inflating unit (124); stitching the first tire components and the second tire components to form the green tire (129); gliding a first set of plurality of turn up arms (127a) with turn up rollers (128) and a second set of plurality of turn up arms (127b) with turn up rollers (128), over the green tire (129) to turn over the excessive first tire components; retracting the first set of plurality of turn up arms (127a) with turn up rollers (128) and a second set of plurality of turn up arms (127b) with turn up rollers (128) back to the initial position; and removing the complete assembled green tire (129) from the said flat drum assembly (130),
characterized in that, said gliding of first set of plurality of turn up arms (127a) with turn up rollers (128) is axially deviated from the axis of the said first outer drum (122) at a predefined angle, said gliding of second set of plurality of turn up arms (127b) with turn up rollers (128) is axially deviated from the axis of the said second outer drum (123) at a predefined angle, thereby the said plurality of turn up arms (127a, 127b) with turn up rollers (128) during the turn up operation of the excess carcass plies are positioned in an axially deviated path inclined to the direction of the cord path.
In the preferred embodiment, the said plurality of turn up arms (127a, 127b) with turn up rollers (128) are positioned in an axially deviated path inclined to the direction of cord path of the green tire (129), preferably, angle of the axial deviation ranges from 0.1° to 45°. The deviation from the cord path distributes the force exerted by the turn up arms (127a,127b) and turn up rollers (128) among the multiple set of cords instead of same set of cords, this reduces/eliminates the resulting indentation/undulation on the final pneumatic tire.
In the preferred embodiment of the present invention, wherein the said first set (127a) and the said second set of plurality of turn up arms (127b) with turn up rollers (128) are operated in clockwise direction, counter clockwise direction, same/parallel direction, opposite direction, forward (head stock) direction, or in reverse (tail stock) direction.
In the preferred embodiment of the present invention, wherein said each of the turn up arm (127a & 127b) is provided with atleast a turn up roller (128), the number of rollers placed on each of the turn up arm is varied based on the drum circumference and number of turn up arms position on the said first outer drum (122) and the said second outer drum (123), wherein said plurality of turn up rollers (128) on the said turn up arm (127a,127b) are positioned in tandem.
In the preferred embodiment of the present invention, wherein said profile of the turn up roller (128) is selected from but not limited to circular, conical, spherical, hemispherical, elliptical, cylindrical and/or combinations thereof.
EXAMPLE 1:
The tire building drum machine (121) of the present invention, used for reducing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, includes the following: the plurality of tire plies are positioned on the said flat drum assembly (130); said plurality of tire plies is inflated by means of the said inflating unit (124) to form the green tire (129); the overhanging plies are turned around the green tire (129) by means of the said plurality of turn up arms (127a &127b) with turn up rollers (128); the plurality of turn up arms (127a & 127b) with turn up rollers (128) moves forward from the tailstock towards the green tire; said movement of the plurality of turn up arms (127a & 127b) deviates from the central axis at a pre-defined angle, wherein said pre-defined angle ranges from 0.1° to 45°, wherein said deviation is in clockwise direction; after turning up, the hanging plies are stitched and the said plurality of turn up arms (127a & 127b) with turn up rollers (128) are retracted back to the tailstock as it moved back/reversed, to its initial position.
EXAMPLE 2:
The tire building drum machine (121) of the present invention, used for reducing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, includes the following: the plurality of tire plies are positioned on the said flat drum assembly (130); said plurality of tire plies is inflated by means of the said inflating unit (124) to form the green tire (129); the overhanging plies are turned around the green tire (129) by means of the said plurality of turn up arms (127a &127b) with turn up rollers (128); the plurality of turn up arms (127a & 127b) with turn up rollers (128) moves forward from the tailstock towards the green tire; said movement of the plurality of turn up arms (127a & 127b) deviates from the central axis at a pre-defined angle, wherein said pre-defined angle ranges from 0.1° to 45°, wherein said deviation is in counter clockwise direction; after turning up, the hanging plies are stitched and the said plurality of turn up arms (127a & 127b) with turn up rollers (128) are retracted back to the tailstock as it moved back/reversed, to its initial position.
EXAMPLE 3:
The tire building drum machine (121) of the present invention, used for reducing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, includes the following: the plurality of tire plies are positioned on the said flat drum assembly (130); said plurality of tire plies is inflated by means of the said inflating unit (124) to form the green tire (129); the overhanging plies are turned around the green tire (129) by means of the said plurality of turn up arms (127a &127b) with turn up rollers (128); the plurality of turn up arms (127a & 127b) with turn up rollers (128) moves forward from the tailstock towards the green tire; said movement of the plurality of turn up arms (127a & 127b) deviates from the central axis at a pre-defined angle, wherein said pre-defined angle ranges from 0.1° to 45°, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) deviates in clockwise direction and the said second set of plurality of turn up arms (127b) with turn up rollers (128) deviates in counter clockwise direction; after turning up, the hanging plies are stitched and the said plurality of turn up arms (127a & 127b) with turn up rollers (128) are retracted back to the tailstock as it moved back/reversed, to its initial position.
EXAMPLE 4:
The tire building drum machine (121) of the present invention, used for reducing/eliminating the undulation effect on the sidewall of the inflated pneumatic tire, includes the following: the plurality of tire plies are positioned on the said flat drum assembly (130); said plurality of tire plies is inflated by means of the said inflating unit (124) to form the green tire (129); the overhanging plies are turned around the green tire (129) by means of the said plurality of turn up arms (127a &127b) with turn up rollers (128); the plurality of turn up arms (127a & 127b) with turn up rollers (128) moves forward from the tailstock towards the green tire; said movement of the plurality of turn up arms (127a & 127b) deviates from the central axis at a pre-defined angle, wherein said pre-defined angle ranges from 0.1° to 45°, wherein said first set of plurality of turn up arms (127a) with turn up rollers (128) deviates in counter clockwise direction and the said second set of plurality of turn up arms (127b) with turn up rollers (128) deviates in clockwise direction; after turning up, the hanging plies are stitched and the said plurality of turn up arms (127a & 127b) with turn up rollers (128) are retracted back to the tailstock, to its initial position.
This improved method of tire tread assembly of the present invention maintains the deformation of the sidewall tread at a desired level and improves the tire tread profile retention. Further the present invention deviates the direction of stitching of the sidewall tread, which makes the assembling unit, in particular the turn up arm and roller unit, to excrete its force in the radial direction. This during the folding/turn-up process of the excess carcass ply, distributes the force exerted by the turn up rollers across the steel cords in radial direction, keeping them intact and preventing them from getting displaced or overlapped, thereby eliminating the sidewall undulation/indentations.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.