WO1999004956A1

WO1999004956A1 - Improvements in tyre manufacture

Info

Publication number: WO1999004956A1
Application number: PCT/GB1998/002194
Authority: WO
Inventors: Eric Holroyd; Colin Holroyd
Original assignee: Holroyd Associates Limited
Priority date: 1997-07-23
Filing date: 1998-07-22
Publication date: 1999-02-04
Also published as: GB9715455D0; AU8454598A; GB2327395A

Abstract

A tyre support for building a pneumatic tyre has a substantially circular body and comprises a plurality of radially extending fingers (24). The fingers (24) are each moveable relative to the body between an extended position and a retracted position. When the fingers are in the extended position, the support defines an external periphery corresponding to an intended final shape of a pneumatic tyre.

Description

Title: Improvements in Tyre Manufacture

The present invention is concerned with improvements in tyre manufacture, particularly in the manufacture of pneumatic tyres.

Vehicle tyres are formed of many separate components, at least some of which are of unvulcanised elastomeric material. The inner carcass of a tyre is particularly important since during tyre construction it tends to impart strength to the tyre and to define the final shape of the tyre.

In the past, the inner plies of a tyre have been constructed in the form of a cylinder, which has subsequently been expanded using compressed air or other gas. The pressures involved in such expansion are relatively high, and so relatively bulky plant has been required. Apparatus which operates in that way is disclosed in U.K. Patent Application GB-A-2153760. Moreover, UK Patents 1524369, 1521987, 1476277, 1287805 and 1172319 and US Patent 3867230 disclose a similar arrangement but which use mechanical rams moveable radially to expand the tyre.

Furthermore, the expanded tyre needed to be transferred to a support jig for fitting with a tread package and for vulcanisation. Such steps are difficult, because it is important not to disturb the unvulcanised inner carcass unduly, otherwise distortion thereof may occur.

U.K. Patent 877480 describes a former on which a carcass is shaped. In that case, the former is tyre shaped. There is no indication as to how the tyre carcass could be removed from the former, and that could pose a significant problem.

U.K. Patent Application GB-A-2135640 describes an inflatable former able to assume a tyre shape. In that case, the former is extremely complicated and relies on the integrity of the bladder. European Patent Application EP-A2-0661150 makes use of support member segments which interlock in a complicated manner so as to define a toroidal support. However, the mechanism is mechanically highly complex, upon which the present invention aims to improve.

According to a first aspect of the present invention, there is provided a tyre support for building a pneumatic tyre, the tyre support having a substantially circular body and comprising a plurality of radially extending fingers spaced around the periphery of the body, the fingers each being moveable relative to the body between an extended position and a retracted position, wherein when the fingers are in the extended position, the support defines an external-periphery corresponding to an intended final shape of a pneumatic tyre.

It is an advantage of the present invention that the shape of the support corresponds substantially to an intended final shape of a pneumatic tyre to be made on the support. Accordingly, the present invention does not require the use of heavy duty moulding equipment for providing large displacements of material at a final expansion step. Furthermore, the fingers may be movable into intermediate positions so that a range of tyre sizes may be built using the support of the present invention. The invention allows a simple apparatus which increases reliability and therefore productivity.

Preferably, the fingers are each mounted on the periphery of the body and are each pivotable on a respective tangential axis of the body.

The plurality of fingers preferably comprises two subsets of fingers, wherein the respective pivot axes of the fingers of each subset are contained in a respective plane perpendicular to the axis of the body, and wherein the fingers of one subset are oriented opposite those of the other subset.

Accordingly, the fingers may be movable to define a tyre shape with a range of possible dimensions of radius, width and profile. The fingers of one subset may be interdigitated with the fingers of the other subset.

When all of the fingers are in the retracted position, the support preferably defines a periphery smaller than the bead diameter of a tyre to be supported thereby.

In that way, a tyre carcass supported by the support can be released therefrom after completion of the carcass.

The support may comprise locking means for locking the fingers in the extended position. That will advantageously improve the rigidity of the support.

Preferably, the body includes attachment means for placement of the support at an assembly station. In that way, the support can be moved between a number of stations adapted to receive such a support, without the need to remove an embryonic carcass therefrom.

In a preferred embodiment, the body comprises first and second substantially circular and parallel body portions, which body portions are separably interlockable, each body portion having a respective subset of said fingers. The first and second portions can be separated after retraction of the fingers, which allows a carcass to be removed from in between the two body portions.

According to a second aspect of the invention, there is provided an assembly station for use with the support described in the preceding paragraph, the station comprising first and second mountings, said mountings being adapted to support respectively the first and second body portions of said support in use. Such a station is, as is previously described, useful in that it can receive a support having an embryonic carcass thereon, perform an operation thereon, and give up the support to another station according to the invention.

The station may comprise drive means operative to rotate a support in use.

The mountings may be moveable relative to each other for separating the first and second body portions of a support in use. That is advantageous as the removal of a carcass from a support can then be conducted mechanically and under control.

Further aspects and advantages of the invention will become apparent from the following description of a specific embodiment of a support and a station in accordance with the invention, with reference to the accompanying drawings in which:

Figure 1 shows a side elevation of a support of a specific embodiment of the invention;

Figure 2 shows a side elevation of an assembly station of a specific embodiment of the invention in conjunction with the support of figure 1 and in an initial state;

Figure 3 shows a side elevation of the assembly station and support of figure 2 in a first intermediate state;

Figure 4 shows a side elevation of the assembly station and support of figure 2 in a second intermediate state; and

Figure 5 shows a side elevation of the assembly station and support of figure 2 in a final state.

As illustrated in figure 1, a support 10 comprises two halves 12, 14. Each half 12, 14 has a cylindrical body 16. The cylindrical body 16 has front and rear circular faces 18, 20. The front faces 18 of the respective bodies 16 face each other as illustrated in figure 1. The front face of each body 16 includes an axial attachment 22 for releasable attachment to the corresponding feature of the other body 16. In that way, the halves 12, 14 are releasably connectable to one another.

A plurality of fingers 24 are spaced around the circumference of the front face 18 of each body 16. Each finger 24 has a supporting arm 26 corresponding generally to a half profile of a tyre to be constructed, and a locating arm 28 substantially perpendicular thereto. Each finger 24 is pivotally mounted on the respective body 16 in a plane radial of the body 16 and on an axis tangential of the body 16 so that the locating arm 28 is directed generally radially inwardly of the body 16.

The front face 18 of each body 16 includes a circular recess 30. A circular locking plate 34 is provided on each half 12, 14 of the support 10, about the axial attachment 22, and is arranged to move axially in to and out of the recess. The locking plate 34 abuts the locating arm 28 of each finger 24. In that way, movement of the locking plate 34 out of the corresponding recess 30 is operative to splay the supporting arms 26 of the fingers 24 radially outwardly.

The right hand half 14 of the support 10 of figure 1 illustrates two possible positions of the fingers 24 and the locking plate 34. The finger 24A illustrated in ghosted line is in a withdrawn or retracted position and the corresponding position of the locking plate has reference numeral 34A. The other position of the locking plate 34 corresponds with the extended position of the finger 24 illustrated in solid line.

The fingers 24 of the two hilves 12, 14 are interdigitated in order to prevent clashes from occurring during movement of the fingers 24.

Adjacent the fingers 24 on the periphery of the body 16 of each half 12, 14 of the support 10 is a circumferentially extending bladder 36. On inflation of the bladder 36, a metal turn up 38 is caused to extend radially outwardly of the body 16.

The rear face 20 of each half 12, 14 has attachment means to allow attachment of the support to an assembly station, in a manner to be described below.

Figure 2 shows an assembly station 40 comprising a headstock 42 and a tailstock 44. Each of the headstock 42 and the tailstock 44 has a cylindrical attachment portion 46 having attachment means corresponding to that of the rear face 20 of a half of the support 10. The attachment portions 46 have control means for controlling the positions of the locking plates 34 and to attach and release the axial attachments 22 of the support 10. Suitable control means could be connecting rods.

A support 10 as described above is shown in figure 2 being introduced into the station 40. The support has been passed through previous processes such that the support has a green tyre carcass applied around it, with bead and apex packages.

The station 40 has a support rod 48 parallel with and generally above the axis of the headstock 42 and tailstock 44. Suspended from the rod are two formers 50, around respective attachment portions 46, holding half tyre tread packages.

In figure 3, the support 10 as previously described is shown installed into the station 40. The formers 50 are shown being moved along the rod 48 closer to the support 10 for fitting of the half tyre tread packages thereabout.

In figure 4, the formers have now been withdrawn leaving the tread packages in place around the support 10. The fingers 24 of the left hand half 12 of the support 10 are retracted and by the application of pressure, the green carcass and the left hand half of the tread package are conformed to shape. The axial attachments 22 are released and the left hand half 12 of the support 10 is withdrawn away from the right hand half 14. Subsequently, the same process is undergone in respect of the right hand half of the tyre carcass and tread package, with the constituent parts being conformed to shape by the application of pressure as the fingers 24 of the right hand half 14 of the support 10 are retracted, as shown in figure 5. In that figure, means for supporting the tyre are omitted for clarity.

The support as described above is a lightweight and versatile structure which allows a tyre carcass to be supported through a manufacturing step. The support may be adjustable such that the tyre thickness may be adjusted by varying the separation between the two halves of the support during use, and the profile may be altered by varying the degree of extension of the fingers from the body.

Claims

1. A tyre support for building a pneumatic tyre, the tyre support having a substantially circular body (16) and comprising a plurality of radially extending fingers (24), the fingers (24) each being moveable relative to the body between an extended position and a retracted position, wherein when the fingers are in the extended position, the support defines an external periphery corresponding to an intended final shape of a pneumatic tyre.

2. A tyre support according to claim 1 wherein the fingers (24) are movable into intermediate positions such that a range of tyre sizes can be built.

3. A tyre support according to claim 1 or claim 2 wherein the fingers (24) are each mounted on the periphery of the body (16) and are each pivotable on a respective tangential pivot axis of the body (16).

4. A tyre support according to claim 3 wherein the plurality of fingers (24) comprises two subsets of fingers (24), wherein the respective pivot axes of the fingers of each subset are contained in a respective plane perpendicular to the axis of the body, and wherein the fingers of one subset are oriented opposite those of the other subset.

5. A tyre support according to claim 4 wherein the fingers (24) of one subset are interdigitated with the fingers of the other subset.

6. A tyre support according to any preceding claim wherein when all of the fingers are in the retracted position, said support defines a periphery smaller than the bead diameter of a tyre to be supported thereby.

7. A tyre support according to any preceding claim comprising locking means (34) for locking the fingers in the extended position.

8. A tyre support according to any preceding claim wherein the body includes attachment means (20) for placement of the support at an assembly station.

9. A tyre support according to any preceding claim wherein the body comprises first and second substantially circular and parallel body portions (12, 14), which body portions are separably interlockable, each body portion having a plurality of said fingers.

10. An assembly station for use with a support (10) according to claim 9, the station comprising first and second mountings (46), said mountings being adapted to support respectively the first and second body portions (12, 14) of said support in use and including means operative to separate the first and second body portions in use.

11. A station according to claim 10 further comprising drive means operative to rotate a support in use.

12. A station according to claim 10 or claim 11 wherein the mountings (46) are moveable relative to each other for separating the first and second body portions (12, 14) of a support in use.