DESC:FIELD OF THE INVENTION
The present invention relates to the field of tyre building drum. More particularly, it relates to a tyre building drum with curved shoulder profile that also provides an extended stable metal support during consolidation. Advantageously the present invention provides a tyre building drum with proper consolidation of ply turn-up.

BACKGROUND OF THE INVENTION
Earlier tyre building drum have straight edge profile. Due to this, the consolidation of ply turn-up at the drum shoulder was very less, sometimes resulting in air-trap. The existing drum shoulder edge profile also results in sidewall folding and air trap during initial phase of green tyre moulding.

Tyre manufacturing typically involves a tire building drum wherein numerous tire components are applied to the drum in sequence, forming a cylindrical shaped tire carcass. In a typical tire building process, various components are applied to the building drum and consolidated. The building drum must then "collapse", to reduce the diameter of the building drum in order to allow the tire builder to remove the green tire from the drum.

While some of the components may be applied on the drum in the initial collapsed condition, some may be applied after a process of expansion. In a typical process an inner liner (a compounded rubber sheet) followed by layer/s of rubberized fabric (ply or plies) are applied on the collapsed drum. The bead hoops (also simply called beads) are then inserted to align with the bead grooves, and the drum expanded, thereby holding the beads in its desired position. The open-ended ply portions that hang outside the bead positions are then turned over the bead, by a mechanism that is part of the building drum or at times a separate entity and a part of building machine accessories.

A typical next operation would be application of tread over the carcass. The ends of tread would then be sitting over the turned-up portion of the plies. Consolidation of tread with plies is achieved using manual rollers and/or by motorized spinners.

Reference may be made to the following:
US Publication number 20150059984 relates to a tire building drum that includes an inboard section, a centre section and an outboard section. The inboard section has a rotating spindle and a sliding shaft, and the sliding shaft is slidable within the spindle. The inboard section further includes a radially expandable bead lock device mounted on the spindle. The centre section has an internal hub mounted on the sliding shaft and further comprises a plurality of tiles that are radially expandable. The outboard section of the drum is mounted on a distal end of the sliding shaft, and further includes a radially expandable bead lock device. The centre section and the outboard section are each axially movable by sliding of the sliding shaft. This publication talks about a total drum design whereas the invention is specifically about shoulder profile of the drum.

Publication number GB825806(A) relates to a rotatable tyre building drum comprising a pair of rigid members which are capable of relative displacement towards and away from each other and are connected to each other by a resilient diaphragm which is capable of taking up a toroidal shape upon inflation thereof, and a pair of bead locating seating rings the effective diameter of each of which is variable independently of the deformation of the resilient diaphragm. This publication talks about a total drum design with an inflatable diaphragm whereas the invention is specifically about shoulder profile of the drum.

US Publication No. 4362592A relates to the ply turn-up and stitching device for use with a tire building drum wherein the building drum supports a tire carcass thereon with ply stock or fabric wound thereon and wherein the fabric extends beyond the edges of the tire building drum. Separate means is provided to place tire beads onto the respective edges of the building drum. The ply turn-up device upon actuation moves a profiled cam to a predetermined position adjacent the drum and then actuates the turn-up device to perform a turn-up of the marginal edges of the ply stock or fabric over the tire beads followed by a stitching of the remaining fabric onto the tire carcass to complete the operation. On return of the ply turn-up device to its remote position, it carries the profiled cam away from the tire building drum to facilitate the removal of the drum. This publication talks about ply turn up mechanism and related design whereas the present invention is specifically about the shoulder profile of the drum.

US Publication No. 7101451B2 relates to the tire building drum with a turn-up device for production of unvulcanized tires, consisting of a horizontally disposed central bearing hollow shaft (1) with a driving spindle extending through the centre of the bearing hollow shaft, around which there are arranged two sets of lever arms (26) with rollers (27), between which a mechanism for supporting bead wires from both sides is located at both sides of a vertical symmetry plane, the mechanism consisting of: an axially movably arranged first guiding disc (21) with radially movably arranged clamping bead segments (33), adapted to cooperate with a mechanism for controlling radial lift of clamping bead segments (33), and an axially movably arranged second guiding disc (34) with radially movably arranged supporting bead segments (32), adapted to cooperate with a mechanism for controlling radial lift of the supporting bead segments (32), wherein the clamping bead segment (33) is provided with a space (3) for receiving supporting arms (9, 9 a) with a bridge (11) of the supporting bead segment (32) and a bearing surface (7) for simultaneous radial lift of the supporting bead segment (32) with the radial lift of the clamping bead segment (33) by the mechanism for controlling radial lift of the clamping bead segments (33). This publication talks about ply turn up mechanism and related bead segment lift design whereas the present invention is about shoulder profile of the drum.

US Publication No. 2605197A relates to a tire building machine in which hand stitching is avoided. The apparatus of the invention comprises a power-driven, reversible tire building drum of the type which is collapsible by means of a brake on the-drum shaft and having bead-applying rings movable axially of the drum, on either side thereof. Endless belt spring stitchers are provided in front of the drum, for certain ply-turning operations, and novel, cone or acorn type stitchers are provided rearwardly of the drum for other ply-turning operations, The latter stitchers are mounted on a generally vertical axis for swinging motion into and out of the end openings of the drum, being arranged for clearing the rim of the drum in this movement, and are also of dual construction to perform different types of stitching, automatically selective in accordance with direction of drum rotation. This publication talks about ply turn up tools, working mechanism and related design whereas the present invention is specifically about shoulder profile of the drum.

Publication No. EP 1562738 A2 relates to the tyre drum including a turn-up mechanism. The tyre drum is provided with a central shaft, two ring segments placed around the shaft and spaced apart for supporting the bead cores and the tyre drum on either side outside of the ring segments being provided with a set of axially extending arms, the arms at a first free end oriented towards the ring segment being provided with a first turn-up means, particularly a turn-up roller, and at an opposite second end being hinged to an axially shiftable arm support, near the first end at least a part of the arms being provided with means for supporting the tyre component, the support means in an initial position forming a circumferential support surface for the tyre components, the tyre drum further being provided with means for shifting the arm supports in order to move the second ends of both sets of arms axially towards each other, the arms being tiltable in radial planes from the initial position to a tilting position in order to thus move the first ends axially and radially while pressing the part of the tyre components situated outside of the ring segments against the expanded part of the tyre components situated within the ring segments, the support means comprising one or more support rollers provided with a support surface for the tyre component, which support roller is rotatably arranged on the arm. This publication talks about drum turn up working mechanism and related design whereas the present invention is about shoulder profile of the drum.

Due to the short and straight shoulder portion of the building drum, the consolidation of tread ends with carcass was inadequate at drum shoulder region. The straight edge profile also resulted in tendency for sidewall folding and air trap between tread ends and ply turn ups, usually noticed only after tyre molding. Accordingly, there is a need for a tyre building drum having better shoulder profile having better drum shoulder profile for proper consolidation of ply turn-up and for better sidewall edge stitching and consolidation with carcass.
OBJECTS OF INVENTION
In order to overcome limitations found in the above listed prior art, the present invention aims to provide a tyre building drum having a curved profile at the shoulder and together with an extended stable metal support at shoulder.

The principal object of the present invention is to provide tyre building drum having a markedly curved shoulder profile together with an extended stable metal support at shoulder.

Another object of the present invention is to provide better consolidation of ply turn-up.

Another object of the present invention is to provide a better sidewall edge stitching and consolidation with carcass.

Yet another object of the present invention is to avoid sidewall folding during initial phase of green tyre molding.

Still another object of the present invention is to provide uniform tread ending.

In the present invention, the drum is provided not only with a markedly larger curve at the shoulder for a smoother turn-up but also with an extended flat metal portion for providing support to the tread and ply assembly at the turn-up area for better consolidation.

SUMMARY OF THE INVENTION
One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.

It is another aspect of the present invention to provide a tyre building drum, comprising a shoulder with a markedly curved profile extended by a solid metal flat portion,
wherein the curved shoulder profile provides a smoother turn-up of ply ending, the extended solid metal flat portion provides a base support to a ply assembly during the turn-up of a tyre and consolidation of the ply ends and consolidation of the tread edges during assembly and stitching of tyre tread with the carcass of a tyre, and the extended solid metal flat portion provides uniform edge sidewall stitching pressure, and
wherein the radius of curvature of the curved shoulder profile is increased to between 1.5 to 3 times greater than the radius of curvature to flatten a green tyre profile at the turn-up area of the tyre and the bead area, the increased radius of curvature of the curved shoulder profile makes the contact area of the extended solid metal portion smoother.

It is another aspect of the present invention to provide a tyre building drum, wherein the radius of curvature of the curved shoulder profile is increased by in the range of 4.0 mm to 9 mm.

It is another aspect of the present invention to provide a tyre building drum, wherein the contact area of the extended solid metal flat portion is increased from 7.0 mm to 30 mm or to turn up ending either lower or higher.

It is another aspect of the present invention to provide a tyre building drum, wherein the curved shoulder profile provides uniform tread ending due to uniform edge sidewall stitching pressure.

It is another aspect of the present invention to provide a tyre building drum, wherein the extended solid metal flat portion is maintained to match with the green ply ending.

BRIEF DESCRIPTION OF THE DRAWINGS:
So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, may be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawing, which form a part of this specification. It is to be noted, however, that the drawing illustrates only a preferred embodiment of the invention and is therefore not to be considered limiting of the invention's scope as it may admit to other equally effective embodiments.
Figure 1a illustrates the schematic view of the curved profile tyre building drum according to the prior art.
Figure 1b illustrates the schematic view of the curved profile tyre building drum according to the present invention.
Figure 2a and Figure 2b illustrate the cross-sectional view of green tyre profile with existing set up and proposed set up respectively.
Figure 3a and Figure 3b illustrate the cross-sectional view of the design of the curved profile tyre building drum according to the prior art and present invention respectively.

DESCRIPTION FOR DRAWINGS WITH REFERENCE NUMERALS:
(10) Tyre building drum
(11) Curved profile
(12) Solid metal flat portion
(14) Shoulder
(R6) Radius of curvature of the proposed curved shoulder profile
(R3) Radius of curvature of the conventional shoulder profile
(R18) Typical Radius of the green tyre with a 2 ply construction used in the proposed shoulder profile
(R13.5) Typical Radius of the green tyre with a 2 ply construction used in the conventional shoulder profile

DETAILED DESCRIPTION OF THE INVENTION
It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

The present invention relates to the field of tyre building drum. More particularly, it relates to a tyre building drum with curved shoulder profile that also provides an extended stable metal support during consolidation.

The present invention provides a tyre building drum having a markedly curved profile together with an extended solid edge bead groove metal support.

Referring to the figures 1(b), 2(b) and 3(b), a tyre building drum (10) has a markedly curved profile (11) together with an extended solid metal portion (12) which acts as base support giving a better consolidation. This set up prevents the folding of sidewall and reduces the air entrapments between components. Radius of the curvature of solid edge bead groove is increased to between 1.5 to 3 times - in this embodiment doubled at drum shoulder (14) to flatten the green tyre profile at rim line.
The base support (12) and hence contact area provides better side wall edge stitching. The extended flat surface also provides better consolidation of tread with carcass. It prevents folding of side wall during initial phase of green tyre moulding due to increased radius of curvature and also helps in providing uniform tread ending due to more uniform stitching pressure.

The radius of curvature dimension is maintained to prevent displacement of bead from the bead grooves, and also to obtain proper curvature. The extended flat portion is so maintained that it substantially matches with the green ply ending. It also covers the maximum turn-up of plies to provide the desired support.

The present invention relates to a tyre building drum (10) with a curved profile drum shoulder, comprising of:
a curved shoulder profile (11) together with an extended solid metal support (12) for giving a better consolidation.

The tyre building drum (10) comprises of a shoulder (14) with a markedly curved profile (11) extended by a solid metal flat portion (12). The curved shoulder profile provides a smoother turn-up of ply ending. The extended solid metal flat portion (12) provides a base support to a ply assembly during the turn-up of a tyre and consolidation of the ply ends and consolidation of the tread edges during assembly and stitching of tyre tread with the carcass of a tyre. The extended solid metal flat portion (12) provides uniform edge sidewall stitching pressure. The radius of curvature (R6) of the curved shoulder profile (11) is increased to between 1.5 to 3 times greater than the radius of curvature (R3) to flatten a green tyre profile at the turn-up area of the tyre and the bead area. The increased radius of curvature (R6) of the curved shoulder profile (11) makes the contact area of the extended solid metal portion (12) smoother.

The radius of curvature of the curved shoulder profile (11) is increased by in the range of 4.0 mm to 9 mm preferably increased from 3mm (prior art) to 6mm (proposed). The contact area of the extended solid metal flat portion (12) is increased from 7.0 mm to 30 mm or to turn up ending either lower or higher. The curved shoulder profile (11) provides uniform tread ending due to uniform edge sidewall stitching pressure. The extended solid metal flat portion (12) is maintained to match with the green ply ending.

Advantages:
• The present invention allows smoother turn-up of ply ends and better consolidation after turn-up.
• The present invention provides better side wall edge stitching due to better base support and increased contact area.
• Better consolidation of tread with carcass is provided due to extended flat surface.
• Provides uniform tread ending due to uniform tread stitching pressure due to consistent support to tread edge stitching.
• It prevents folding of side wall during initial phase of green tyre moulding due to increased radius of curvature at drum shoulder.

Although, the invention has been described and illustrated with respect to the exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions may be made therein and thereto, without parting from the spirit and scope of the present invention. ,CLAIMS:WE CLAIM:
1. A tyre building drum (10), comprising a shoulder (14) with a markedly curved profile (11) extended by a solid metal flat portion (12),
characterized in that, the curved shoulder profile provides a smoother turn-up of ply ending, the extended solid metal flat portion (12) provides a base support to a ply assembly during the turn-up of a tyre and consolidation of the ply ends and consolidation of the tread edges during assembly and stitching of tyre tread with the carcass of a tyre, and the extended solid metal flat portion (12) provides uniform edge sidewall stitching pressure, and
wherein the radius of curvature (R6) of the curved shoulder profile (11) is increased to between 1.5 to 3 times greater than the radius of curvature (R3) to flatten a green tyre profile at the turn-up area of the tyre and the bead area, the increased radius of curvature (R6) of the curved shoulder profile (11) makes the contact area of the extended solid metal portion (12) smoother.

2. The tyre building drum (10) as claimed in claim 1, wherein the radius of curvature of the curved shoulder profile (11) is increased by in the range of 4.0 mm to 9 mm.

3. The tyre building drum (10) as claimed in claim 1, wherein the contact area of the extended solid metal flat portion (12) is increased from 7.0 mm to 30 mm or to turn up ending either lower or higher .

4. The tyre building drum (10) as claimed in claim 1, wherein the curved shoulder profile (11) provides uniform tread ending due to uniform edge sidewall stitching pressure.

5. The tyre building drum (10) as claimed in claim 1, wherein the extended solid metal flat portion (12) is maintained to match with the green ply ending.