pneumatic tire manufacturing technology and provide a generally cylindrical surface which can be reduced to permit removal of the former from the wound rim or wheel.
Preferred embodiments of the present invention will 5 now be described with reference to the accompanying diagrammatic drawings, in which:
FIGS. 1 and 2 are respectively a perspective view and a side view of one embodiment of apparatus for carrying out the method of the invention; 10
FIG. 3 is a sectional view of a rim wound onto a two-part former;
FIG. 4 is a view similar to FIG. 3 illustrating the manufacture of a wheel by means of a modification of the apparatus illustrated in FIGS. 1 and 2; 15
FIG. 5 illustrates a means of crimping a channel onto a rim end edge, and
FIGS. 6 to 11 illustrate alternative wheels constructed in accordance with the present invention.
FIGS. 1 and 2 illustrate apparatus whereby the wheel 20 rim 10 of FIG. 3 may be manufactured. The apparatus comprises a rotatable former 11 which comprises two similar parts 12 and 13 which are jointly rotatable on a coaxial shaft 14 and are axially displaceable thereon so as to be separable for removal from within the finished 25 rim 10. The two parts of the former 11 have a joint periphery which is similar in configuration to the rim 10 to be produced.
In the embodiment illustrated the former 11 is provided with a slot into which the bent-down, leading end 30 of a tapered tongue 15 of a continuous strip of sheet metal may be introduced to provide an initial attachment between the strip and former. This radially inwardly projecting tongue can subsequently be removed from the interior of the finished rim 10. It will be appre- 35 ciated that any other suitable method could be adopted for temporarily securing the leading end of the tongue 15 to the former 11. For example the former could be provided with studs or pegs, (not shown), engaging in holes therefor in the tongue 15. 40
The tongue 15 is formed at the leading end of a continuous strip of flat sheet metal, suitably aluminium or steel of a thickness in the range 0.2 to 0.5 mm which is wound off a supply roll (not shown). En route to the former 11 the strip 16 passes over a table 17 and then 45 between oppositely tapered rollers 18 and 19 which impart to the strip 16 a channel shape such that it has a shallow V section prior to reaching the periphery of the former 11. As it arrives tangentially at the periphery of the former 11 the strip 16 passes between the former 11 50 and a roller 20 (omitted from FIG. 1 for ease of illustration) which has a periphery complementary to that of the former 11 so that the strip 16 is subject to two forces tending to deform it to the shape of the former periphery, namely the longitudinal tension produced in the 55 strip 16 by the tractive force of the former 11 as the latter is rotated and pressure exerted by the roller 20 onto the strip 16 against the former.
When the former 11 has completed one revolution a strip 21 of adhesive is introduced into the nip between 60 the former 11 and roller 20 and fed to the former 11 jointly with the strip 16 so as to be interposed between subsequent turns of the metal strip 16. The adhesive may be any suitable epoxy, polymer or phenolic resin adhesive and such are commercially available in ribbon 65 form usually backed by paper or the like strip, or the adhesive may be a liquid which can be applied to the strip prior to winding and allowed to gel or can be
sprayed on during winding. A roller 22 is illustrated over which the ribbon or adhesive can be introduced to the former 11 and other rollers (not shown) may be provided around which the paper backing of the strip may be removed prior to insertion of the adhesive between the turns of the metal strip 16. An adhesive may be chosen of the kind which saturates or coats a strand of filamentary material or a textile strip which therefore becomes incorporated in the finished rim, imparting to it particular characteristics of strength and resilience. Alternatively, or in addition, there may be incorporated one or more turns of a high strength, composite material such as carbon fiber ribbon or cloth, impregnated with suitable polymerizing adhesive in its unpolymerized state.
In the manufacture of certain types of wheel, e.g. aircraft wheels, it may be desirable to provide a substantial quantity of high strength composite material between the metal windings.
When the desired number of turns of the strip 16 has been wound onto the former 11 the wound-on strip may be severed from the supply using a tool or tools acting downwardly on the table 17. Preferably the strip 16 is transversely scored and/or perforated in such a way that the trailing end of the severed strip is feathered or tapered so that there is no sharp projection on the radially outer surface of the finished rim. Excess adhesive may be used to smooth any such projection or if necessary the finished rim may be subjected to a grinding or buffing operation to smooth off the trailing end of the strip. The severing action can be performed by continuing to turn the mandrel while applying further tension to the feed strip by means of a suitable adjustable friction clamp, thus ensuring a tightening of the final winding.
Alternatively or in addition the trailing end of the strip may be fixed to the subjacent turn by lazer spot welds.
The finished rim 10 as shown in FIG. 3 comprises bead retention flanges 23 and 24 at its axial ends, a central tire mounting well 25 and bead seats 26 and 27 between the bead retention flanges and the well. This configuration is such that the diameter of the rim 10 reduces in a series of steps from its axial ends towards its center and this makes it possible to remove the former 11 from the finished rim simply by separating the two parts 12 and 13 of the former along the axis of the shaft 14. If an adhesive is used which must be allowed to set, or heat cured, subsequent to the winding and severing operations the wound rim may be secured against unwinding while it is removed from the mandrel and, e.g. placed in a curing oven by temporarily placing round the rim a high strength textile strap tensioned with a tensioning tool.
FIG. 4 illustrates a former 28 of a basically similar but more complex construction for the production of a vehicle wheel which comprises a disc portion 29 and a rim 30. The former 28, rotatable about the axis of a mounting tube 31, comprises circular plates 32 and 33 which support segmented annular blocks 34 and 35 on annular shoulders 36 and 37. An axially extending flange 38 at the radially outer periphery of the disc 29 overlies the block 34 in such a way that it forms an annular projection over which the windings of the rim 30 are bent down. The effect of this arrangement is that the flange 38 is entrapped within the windings so that the disc 29 is incapable of axial displacement relative to the rim 30. Relative rotation between the disc 29 and