GB1585279A - Method of forming rings - Google Patents

Description

(54) METHOD OF FORMING RINGS (71) I, EDWARD GEORGE SPISAK, of 35700 Oakwood Lane, Westland, Michigan 48185, United States of America, a citizen of United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method of manufacturing annular rings, particularly, but not exclusively, from a strip of elongated material.

In the formation of metal rings in which a substantial portion of the material in the finished ring is to be disposed in a radial rather than in an axial direction, it has been customary to cut a flat annular ring from a flat sheet of metal and thereafter, to form the flat annular ring between dies affording the desired shape, usually with portions of the material being disposed in both an axially and radially extending direction. This results in a great waste of stock material since the unused material from the flat sheet usually is far in excess of the material content in the finished ring.

In an attempt to form annular rings in which a substantial portion of metal is disposed radially rather than axially, various methods have been attempted employing conventional manufacturing equipment and techniques. Annular rings have been formed by roll forming or die forming between opposed dies and by spinning. However, all of such processes employ mating dies in which portions of the metal become clamped between the dies while remaining portions are displaced. This causes the metal to be stretched up to or beyond its limits of elongation so that stretch marks and flaws are formed in the material which is particularly undesirable if the annular rings are of very thin metal or are to be used for ornamental purposes. In an attempt to avoid such stretching and marking, multiple step operations have been conducted to progressively form the annular ring and to size it. This requires excessive and elaborate equipment making the process economically unsound since the cost of the equipment is out of proportion to the savings in material.

A method of forming an annular ring having a generally U-shaped cross-section is provided in my U.K. Specification No.

1,542,343, in which a cylindrical workpiece with its material extending axially may be formed of an elongated strip of material and is supported on forming apparatus within the cylinder over the entire inner circumference and at axially spaced areas. A force is exerted radially outwardly to displace material between the supported surfaces until the resultant workpiece has at least a portion of its cross-sectional material content disposed radially. Thereafter, the workpiece can be separated into two rings in which the bulk of the cross-sectional material is disposed radially and results in a pair of annular rings which are free of stretch marks. The process makes it possible to displace material originally disposed axially of the ring in a generally radial direction without exceeding the elongation limits of the material. The method of my Specification No. 1,542,343 permits the facility to allow the marginal edge portions of the cylindrical workpiece to remain in a generally axial orientation after forming the annular ring, but in some cases this facility is not required, and it is an object of the present invention to simplify the method of Specification No. 1,542,343 for use in such cases.

According to the present invention there is provided a method of forming an annular ring having a generally U-shaped crosssection from an endless, annular workpiece in which the material extends axially, the method comprising positioning the workpiece relative to forming apparatus capable of exerting a force radially outwardly in all directions on an inner circumferential portion of the workpiece, actuating the forming apparatus to engage said inner circumferential portion and exert said force between spaced annular marginal edge portions of the workpiece to displace the material in the workpiece radially outwardly until the material in the marginal edge portions is disposed generally radially, the force being applied on the inner circumferential portion of the workpiece while all remaining portions of the radially inner and outer surfaces of the workpiece remain unsupported.

Further according to the present invention there is provided a method of forming annular rings with material oriented radially from an endless annular workpiece in which the material is oriented axially, the method comprising applying a force to the workpiece surface over an annular portion between marginal edge portions thereof while all the remaining portions of the inner and outer surfaces of the workpiece remain unsupported, the force being applied until tlie marginal edge portions extend generally radially to form a ring member having a substantially U-shaped cross-section, and dividing the ring member intermediate the marginal edge portions to form two substantially identical annular rings.

Still further according to the present invention there is provided a method of making a decorative trim ring for wheels comprising: cutting a strip of elongated material to a length no greater than the inner circumference of the ring to be formed, abutting the ends of said strip of material, applying heat to the abutting ends of said workpiece to fuse said ends together without adding material, to form an endless, circular workpiece in which the material is disposed axially, applying a force radially outwardly in all directions on a selected inner annular surface disposed between marginal edge portions of the workpiece to disp]ace material radially outwardly, said force being applied while all the remaining portions of the radially inner and outer surfaces of the workpiece are unsupported, the displacement continuing until the marginal edge portions of the workpiece extend generally radially to form a ring with a generally U-shaped cross-section.

The method of the present invention will now be described, by way of example only, and with contrast to the method described and claimed in my U.K. Specification No.

1,542,343, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a ring formed in accordance with the method of Specification No. 1,542,343; Figure 2 is a cross-sectional view at an enlarged scale of the ring shown in Figure 1; Figure 3 is a schematic illustration of welding apparatus employed in preparing a cylindrical workpiece for use in the method of the present invention Figure 4 is a view of a portion of Figure 3 showing a further condition of operation of the apparatus; Figure 5 is a schematic side elevation of part of the apparatus shown in Figures 3 and 4; Figure 6 is a perspective view of a cylindrical workpiece formed on the apparatus of Figures 3 to 5; Figure 7 is a schematic illustration of forming apparatus employed in carrying out the method of Specification No.

1,542,343; Figure 8 is a view taken generally on line 8-8 in Figure 7; Figures 9, 10, 11 and 12 are schematic illustrations showing progressive steps in the expansion of a workpiece on the apparatus of Figures 7 and 8; Figures 13 and 14 illustrate progressive steps in the formation of one of a pair of decorative rings from the ring shown in Figure 2; Figure 15 is a cross-sectional view of a decorative trim rim of the type used for automotive wheels in which the decorative portion is made from the ring shown in Figures 13 and 14; Figures 16, 17 and 18 illustrate porgressive steps in the formation of another form of decorative ring on the apparatus of Figures 7 and 8; Figure 19 is a view similar to Figure 11 illustrating a modified form of ring formed by the method disclosed in U.K. Specification No. 1,542,343; Figure 20 is a cross-sectional view of a portion of a ring similar to that seen in Figure 2 except that all of the material in the marginal edges of the ring is disposed radially, the ring having been formed in accordance with the present invention; Figure 21 is schematic illustration of forming apparatus similar to the one seen in Figure 7 and employed in the method of the present invention; Figure 22 is a cross-sectional view of a workpiece and adjacent parts of the forming apparatus of Figure 21 prior to exerting a force to displace the material of the cylindrical workpiece; Figure 23 is a view similar to Figure 22 showing a relative position of the parts after the material has been fully displaced; Figures 24 and 25 illustrate progressive steps in forming a decorative ring from the ring shown in Figure 20; and Figure 26 is a cross-section of a trim ring assembly of a type used on vehicles and using the decorative ring shown in Figure 25.

The method of the present invention is applicable to the formation of annular rings in which substantially all the material in the ring is disposed in a radial direction relative to the axis of the ring and in which the ring is formed by displacing material, usually metal, from a cylindrically shaped workpiece originally having its material ex tending in an axial direction. This makes it possible to form the ring from elongated strip stock as opposed to the formation of rings from blanks of material cut from flat plate material.

Referring to the drawings, to form an annular ring 10a by the method of the present invention, the cylindrical workpiece may be prepared by cutting a strip of metal to a length conforming substantially to the inner circumference of the finished ring. The width of the strip of material is equal to the length of the finished cross-section of the ring, as shown in Figure 20. Referring particularly to Figures 3 to 5, the strip of material is subsequently bent into a circular form so that the ends 12 are adjacent to each other. This forms an initial workpiece 14 which requires joining, such as by welding, of the adjacent ends 12.

The welding apparatus of Figures 3 to 5 includes two lower clamps 16 and 17 and respective upper clamps 18 and 19. The clamps 16 and 18 are initially separated from the clamps 17 and 19 by a gauge bar 20, as shown in Figure 4. The gauge bar 20 may be reciprocated horizontally relative to the clamps 16, 17, 18 and 19 by means of a hydraulic actuator or cylinder 22. The clamps 18 and 19 may be moved generally vertically relative to the lower clamps 16 and 17 by means of hydraulic cylinders 24.

The welding apparatus also includes a welding head or nozzle 26 which as shown in Figure 5 is supported on a horizontal track 28 for reciprocation in a horizontal direction by motor means indicated at 30. Provision is also made for retracting the welding head 26 upwardly and to an angular position, as indicated in broken lines, for retraction of the welding head 26 after a weld is completed. Preferably, the welding head forms a portion of a plasma type welding system by which adjacent ends 12 of the workpiece 14 are fused together in an oxygen free atmosphere such as argon gas, utilising the material of the workpiece 14 and without the addition of any material by way of an electrode.

In an initial position of the welding apparatus, the clamps 16 and 18 are disposed at one side of the gauge bar 20 and the clamps 17 and 19 are disposed at the other side of the guage bar 20. Also, the upper clamps 18 and 19 are spaced from the lower clamps 16 and 17 to receive the workpiece 14. The workpiece 14 is positioned with its ends 12 in abutment with the gauge bar 20, after which the hydraulic actuators 24 are operated to clamp the left end of the workpiece 14 between the clamps 16 and 18 and the right end of the workpiece 14 between the clamps 17 and 19. Thereafter, the hydraulic actuator 22 is operated to retract the gauge bar 20 from between the clamps 16, 18 and 17, 19 to the position shown in Figure 5. By mechanism not shown, the right clamps 17 and 19 and left clamps 16 and 18 are moved toward each other to bring the ends 12 of the workpiece 14 into adjacent relationship with each other, as shown in Figure 3. With the workpiece 14 in this position, the welding head or nozzle 26 is advanced towards the left as viewed in Figure 5, to fuse the ends 12 of the workpiece 14 together to form a generally cylindrical ring-like workpiece which will hereafter be designated as 28, as shown in Figure 6.

Preferably the welding process employed is one in which the virgin material alone is required to form a weld and further material is not added. One such method is the plasma welding method which is preferred in the making of rings which are to be used for decorative purposes and are made of material such as stainless steel. By using the plasma method in which no material is added, the welded portion of the ring is almost undetectable after formation of a decorative ring.

After the workpiece 28 is formed, the hydraulic actuator 22 is operated to return the gauge bar 20 to the left to the position shown in broken lines in Figure 5. During such movement, the end of the gauge bar 20 engages the ring 28 and ejects it from the apparatus leaving the gauge bar 20 in position between the left and right clamps in readiness to receive the next workpiece 14.

After the weld has been formed in the ring 28, it may be desirable to perform finishing operations on the weld, particularly if the ring to be formed is for ornamental purposes. Such finishing operations may be performed by planishing in which the welded portion of the ring 28 is moved between opposed rollers which carefully size the material to that of the original thickness of the strip 14. If necessary, the weld may also be ground to buffed.

After the ends 12 of the workpiece 28 have been joined, it is ready for expanding from its generally cylindrical form, as shown in Figure 6, to form a ring 10a having a cross-section such as shown in Figure 20.

The apparatus employed for forming the ring 10a from the workpiece 28 is an expanding machine 32a shown in Figure 21.

The expanding machine 32a is similar to the machine 32 shown in Figures 7 and 8 which is used for forming annular rings such as 10 in Figures 1 and 2 in accordance with the method of my U.K. Specification No. 1,542,343, and for convenience the machine 32 and its operation and uses will be described in the following paragraphs with the distinguishing features of the machine 32a described thereafter.

The expanding machine 32 is generally described as a cone type expanding machine or an expanding mandrel machine. As seen in Figure 8, the machine includes a plurality of segment assemblies 34, each of which includes a jaw 36 and a forming shoe or punch 38 detachably connected together. In their initial or retracted position the segment assemblies 34 are disposed in contact with each other, as shown in Figure 8, and define an annular ring the centre of which receives a cone 40. The cone 40 is connected by means of a draw bar 42 to a mechanism such as a hydraulic actuator 44 by which the cone may be pulled downwardly or raised upwardly.

The jaws 36 are formed with an angular surface 46 conforming to the angular surface 47 of the cone 40. In the initial retracted position of the segment assemblies 34, as seen in Figures 7 and 8, all of the angular surfaces 46 are in engagement with the surface 47 of the cone 40. Operation of the hydraulic cylinder 44 to retract the latter, serves to move the cone 40 downwardly (in Figure 7) which causes all of the segment assemblies 34 to be moved radially outwardly simultaneously and equally relative to the axis of the cone 40.

Thus far, the expanding machine 32, which has been described is more or less conventional. However, to form the annular ring 10, the machine 32 includes a lower support member 48 and an upper support member 50. Support members 48 and 50 form annular rings which are supported relative to the expanding machine 32 and to each other with a spacing sufficient to receive punch portions 52 of the forming shoes 38 therebetween.

To operate the machine 32, a ring-like cylindrical workpiece 28 is positioned so that its inner circumferential surface 54 is in facing relationship with the outer circumferential surfaces 56 and 58 of respective support members 48 and 50. Thereafter, with reference to Figure 7, the hydraulic actuator 44 is operated to pull the draw bar 42 downwardly so that the cone 40 also moves downwardly and its surface 47 slides on the surfaces 46 of the segment assemblies 34 simultaneously moving all of the assemblies radially outwardly from the axis of the cone. Such movement causes the punch portions 52 of the segment assemblies 34 to engage the inner circumferential surface 54 of the cylindrical workpiece 28.

During initial movement of the segment assemblies 34, metal in the workpiece 28 is displaced outwardly as shown in Figure 9. Continued movement of the segment assembly 34 further displaces the material in the workpiece to form an annulus having a generally U-shaped cross-section, as indicated at 60 in Figure 10. Upper and lower marginal edge portions 62 and 64 of the workpiece 28 remain in contact with the support members 48 and 50. Radially outward movement of the segment assemblies 34 can be continued by further downward movement of the cone 40, to progressively displace the material of the workpiece 28 until it takes the configuration shown in Figure 11 or Figure 12, depending on the desired cross-sectional shape to be attained.

During expansion or displacement of the material in the workpiece 28 radially outwardly on the apparatus of Figure 7, it will be noted that the support members 48 and 50 act to prevent the marginal edges 62 and 64 from being displaced radially. Moreover, as the material is being displaced radially outward to form the U-shaped portion 60, the material in the marginal edge portions 62 and 64 slides on the surfaces of the supports 48 and 50 and is displaced axially toward the centre or U-shaped portion. The material in the marginal edges and in the U-shaped portion retains its original thickness since during radial expansion the material is unsupported at the radially outer surfaces of the annular ring and the material is free to slide or flow in response to the radial forces exerted by the segment assemblies 34.

The method described immediately above is particularly useful in forming annular rings in which the marginal edge portions 62 and 64 remain undistorted. It will be observed that during the forming operation the entire outer circumferential surface of the workpiece is completely unsupported and unconfined, unlike prior types of operations which use a female die to receive the material of the workpiece. The method is particularly useful in forming thin material into ornamental annular rings such as those used for decorative wheel trim on automotive vehicles. This may be accomplished by forming an annular ring having a crosssection such as that seen in Figure 2, and threafter the ring 10 may be cut in a plane passing through the bight of the U-shaped portion 60 to form a pair of identical rings 66, such as shown in Figure 13. Thereafter, the ring 66 may be formed by conventional methods to take the configuration shown in Figure 14 in readiness to receive a retaining ring assembly 68, as seen in Figure 15.

The retaining ring assembly 68 includes an annular ring 70 which may be formed by conventional methods and may be of a lower grade material than the decorative ring 66. The annular ring 70 is provided with a plurality of retaining devices 72, only one of which is shown, which are connected to the retaining rings 70 by means such as rivets 74. The retaining ring assembly 68 may be connected to the decorative ring 66 by folding over a flange portion 76 from the position from which it is shown in Figure 13 to the position in which it is shown in Figure 14.

Annular rings of various configuration may be formed on the apparatus 32, for example as shown in Figures 11 or 12, which may be later separated into a pair of rings similar to those shown in Figure 13.

Such an operation makes for high production rates and results in annular rings in which a substantial portion of the material is disposed radially relative to the axis of the ring without, for example, the formation of wrinkles, stretch lines or thinning of the metal, as occurs in conventional methods of forming with co-acting male and female dies.

An example of another form of ring crosssection which may be formed by the expanding machine 32 is illustrated in Figure 19 at 77. In this instance the forming shoe or punch 38a is formed with punch portion 52a which merges with shoulder portions so that after expansion, the ring 77 has a U-shaped portion merging with oppositely diverging skirt portions 78 which in turn merge with axially extending flange portions 62a and 64a. Still other forms of forming shoes or punches 38a may be used to provide various other configurations of ring cross-sections.

If desired, the expanding machine 32 can be employed in forming annular rings of more complex shape as illustrated, for example, in Figures 16 to 18. To form a ring 80 having the cross-sectional configuration shown in Figure 18, require the prior formation of a ring-like workpiece 82 having an axial dimension equal to the length of the cross-section of the ring 80. To form the ring 80, the workpiece 82 is positioned as illustrated in Figure 16, and upon radial extension of the segment assemblies 34 a lower marginal portion of the workpiece 72 is formed with a U-shaped portion as indicated at 84 in Figure 17. Thereafter, the segment assemblies may be retracted by moving the cone 40 upwardly and the workpiece may be moved axially relative to the support members 48 and 50 and to the shoe 38 from the position illustrated in Figure 17 to a lower position after which the segment assembly 34 may be again dis placed radially to displace metal in the upper marginal edge of the workpiece 82 to form a second U-shaped portion 86. The annular ring 80 may be severed at the points indicated at 88 to form four substantially identical rings each having a major portion of its material disposed radially of the axis of the rings.

In contrast to the method described with reference to the expanding machine 32, when it is desired to form a ring 10a hav ing the cross-sectional configuration seen in Figure 20, in which a maximum of the material in the ring is disposed radially including the marginal edge portions 62 and 64 the ring may be formed in accordance with the method of the present invention on the expanding machine 32a seen in Figure 21. The machine 32a is generally identical to that seen in Figure 7 with the exception that the lower support ring 48 and the upper support ring 50 are omitted.

The forming punches or shoes 38 contact an annular portion of the workpiece between the marginal edges 62 and 64 and form the sole support for the ring on the radially inner and outer surfaces as the material is being displaced radially outwardly. In this instance the movement of the punches 38 is continued radially outwardly a sufficient distance so that a maximum of the material is disposed radially and so that the end faces of the ring la are directed radially inwardly as opposed to facing axially outwardly as with the ring configuration seen in Figure 2.

After the annular ring 10a with the crosssection seen in Figure 20 is formed, it may be cut centrally of the bight of the Ushaped portion to form a pair of identical rings 66a in which a major portion of the material is distributed radially as shown in Figure 24. Conventional material working methods may be used to form a decorative ring 80, seen in Figure 25, from the ring 66a formed by the method of the present invention in preparation for use in a retaining ring assembly 68a as seen in Figure 26.

The retaining ring assembly 68a includes an annular retaining ring 70a which can be formed by conventional methods of a lower grade material than the relatively more expensive decorative material used in forming rings 66a. The annular ring 70a is provided with circumferentially spaced retaining devices 72a, only one of which is shown, but which are adapted to engage and hold the ring assembly on the wheel of a vehicle.

The decorative ring portion 80 and the retaining ring 70a are held together by folding over flange portions 82 and 84 of the ring 80 over the retaining ring 70a.

WHAT I CLAIM IS: 1. A method of forming an annular ring having a generally U-shaped crosssection from an endless, annular workpiece in which the material extends axially, the method comprising positioning the workpiece relative to forming apparatus capable of exerting a force radially outwardly in all directions on an inner circumferential portion of the workpiece, actuating the forming apparatus to engage said inner circumferential portion and exert said force between spaced annular marginal edge portions of the workpiece to displace the material in the workpiece radially outwardly until the material in the marginal edge

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. Figure 13 to the position in which it is shown in Figure 14. Annular rings of various configuration may be formed on the apparatus 32, for example as shown in Figures 11 or 12, which may be later separated into a pair of rings similar to those shown in Figure 13. Such an operation makes for high production rates and results in annular rings in which a substantial portion of the material is disposed radially relative to the axis of the ring without, for example, the formation of wrinkles, stretch lines or thinning of the metal, as occurs in conventional methods of forming with co-acting male and female dies. An example of another form of ring crosssection which may be formed by the expanding machine 32 is illustrated in Figure 19 at 77. In this instance the forming shoe or punch 38a is formed with punch portion 52a which merges with shoulder portions so that after expansion, the ring 77 has a U-shaped portion merging with oppositely diverging skirt portions 78 which in turn merge with axially extending flange portions 62a and 64a. Still other forms of forming shoes or punches 38a may be used to provide various other configurations of ring cross-sections. If desired, the expanding machine 32 can be employed in forming annular rings of more complex shape as illustrated, for example, in Figures 16 to 18. To form a ring 80 having the cross-sectional configuration shown in Figure 18, require the prior formation of a ring-like workpiece 82 having an axial dimension equal to the length of the cross-section of the ring 80. To form the ring 80, the workpiece 82 is positioned as illustrated in Figure 16, and upon radial extension of the segment assemblies 34 a lower marginal portion of the workpiece 72 is formed with a U-shaped portion as indicated at 84 in Figure 17. Thereafter, the segment assemblies may be retracted by moving the cone 40 upwardly and the workpiece may be moved axially relative to the support members 48 and 50 and to the shoe 38 from the position illustrated in Figure 17 to a lower position after which the segment assembly 34 may be again dis placed radially to displace metal in the upper marginal edge of the workpiece 82 to form a second U-shaped portion 86. The annular ring 80 may be severed at the points indicated at 88 to form four substantially identical rings each having a major portion of its material disposed radially of the axis of the rings. In contrast to the method described with reference to the expanding machine 32, when it is desired to form a ring 10a hav ing the cross-sectional configuration seen in Figure 20, in which a maximum of the material in the ring is disposed radially including the marginal edge portions 62 and 64 the ring may be formed in accordance with the method of the present invention on the expanding machine 32a seen in Figure 21. The machine 32a is generally identical to that seen in Figure 7 with the exception that the lower support ring 48 and the upper support ring 50 are omitted. The forming punches or shoes 38 contact an annular portion of the workpiece between the marginal edges 62 and 64 and form the sole support for the ring on the radially inner and outer surfaces as the material is being displaced radially outwardly. In this instance the movement of the punches 38 is continued radially outwardly a sufficient distance so that a maximum of the material is disposed radially and so that the end faces of the ring lûa are directed radially inwardly as opposed to facing axially outwardly as with the ring configuration seen in Figure 2. After the annular ring 10a with the crosssection seen in Figure 20 is formed, it may be cut centrally of the bight of the Ushaped portion to form a pair of identical rings 66a in which a major portion of the material is distributed radially as shown in Figure 24. Conventional material working methods may be used to form a decorative ring 80, seen in Figure 25, from the ring 66a formed by the method of the present invention in preparation for use in a retaining ring assembly 68a as seen in Figure 26. The retaining ring assembly 68a includes an annular retaining ring 70a which can be formed by conventional methods of a lower grade material than the relatively more expensive decorative material used in forming rings 66a. The annular ring 70a is provided with circumferentially spaced retaining devices 72a, only one of which is shown, but which are adapted to engage and hold the ring assembly on the wheel of a vehicle. The decorative ring portion 80 and the retaining ring 70a are held together by folding over flange portions 82 and 84 of the ring 80 over the retaining ring 70a. WHAT I CLAIM IS:

1. A method of forming an annular ring having a generally U-shaped crosssection from an endless, annular workpiece in which the material extends axially, the method comprising positioning the workpiece relative to forming apparatus capable of exerting a force radially outwardly in all directions on an inner circumferential portion of the workpiece, actuating the forming apparatus to engage said inner circumferential portion and exert said force between spaced annular marginal edge portions of the workpiece to displace the material in the workpiece radially outwardly until the material in the marginal edge

portions is disposed generally radially, the force being applied on the inner circumferential portion of the workpiece while all remaining portions of the radially inner and outer surfaces of the workpiece remain unsupported.

2. A method as claimed in claim 1 in which the endless workpiece is formed of an elongated strip of metal whose ends are connected to each other.

3. A method as claimed in claim 2 in which the ends of the strip are joined by plasma welding.

4. A method as claimed in claim 2 or claim 3 in which the length of the strip is substantially equal to the inner circumference of the annular ring.

5. A method as claimed in any one of the preceding claims in which the marginal edge portions of the annular ing are disposed parallel to each other.

6. A method of forming annular rings with material oriented radially from an endless annular workpiece in which the material is oriented axially, the method comprising applying a force to the workpiece surface over an annular portion between marginal edge portions thereof while all the remaining portions of the inner and outer surfaces of the workpiece remain unsupported, the force being applied until the marginal edge portions extend generally radially to form a ring member having a substantially Ushaped cross-section, and dividing the ring member intermediate the marginal edge portions to form two substantially identical annular rings.

7. A method of forming an annular ring substantially as herein described with reference to Figures 20 to 26 of the accompanying drawings.

8. An annular ring formed by the method claimed in any one of the preceding claims.

9. A method of making a decorative trim ring for wheels comprising: cutting a strip of elongated material to a length no greater than the inner circumference of the ring to be formed, abutting the ends of said strip of material, applying heat to the abutting ends of said workpiece to fuse said ends together without adding material, to form an endless, circular workpiece in which the material is disposed axially, applying a force radially outwardly in all directions on a selected inner annular surface disposed between marginal edge portions of the workpiece to displace material radially outwardly, said force being applied while all the remaining portions of the radially inner and outer surfaces of the workpiece are unsupported, the displacement continuing until the marginal edge portions of the workpiece extend generally radially to form a ring with a generally U-shaped cross-section.

10. A method as claimed in claim 9 in which the substantially U-shaped ring is divided circumferentially to form two decorative rings.

11. A method as claimed in claim 10 in which supports are mounted on the decorative rings to enable attachment of the decorative rings to respective wheels.

12. A method of forming decorative trim rings for wheels substantially as herein described with reference to Figures 20 to 26 of the accompanying drawings.

13. A decorative trim ring for a wheel when formed by the method claimed in any one of claims 9 to 12.