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Patent Searching and Data


Title:
A FRAME AND METHOD OF MAKING IT
Document Type and Number:
WIPO Patent Application WO/1995/007835
Kind Code:
A1
Abstract:
Frame members of a bicycle frame are formed at at least one end with a formation comprising a complex curved shape (8) to abut an adjacent frame member and with a tab or tabs (9) enabling that end to be located with respect to the adjacent frame member. These formations are advantageously produced by means of a laser operating under programmed computer control. Frame members are assembled using the locating tabs and then welded together. A jig may be used to hold the members during welding. This greatly facilitates the accurate manufacture of the frame.

Inventors:
CATER ALAN JAMES (GB)
Application Number:
PCT/GB1994/002022
Publication Date:
March 23, 1995
Filing Date:
September 16, 1994
Export Citation:
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Assignee:
RALEIGH INDUSTRIES LTD (GB)
CATER ALAN JAMES (GB)
International Classes:
B62K19/20; (IPC1-7): B62K19/20
Foreign References:
EP0524599A21993-01-27
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Claims:
5CLAIMS
1. A frame member for the frame of a bicycle, tricycle or the like in whic characterised in that at least one end is shaped to abut an adjacent frame member (5) and to produce a formation (9) enabling that end to be located with respect to the adjacent frame member (5).
2. A frame member as claimed in claim I, in which the shape of the end comprises a complex curve (8) adapted to accept the complementary outer curved surface of the adjacent frame member (5).
3. A frame member as claimed in claim I, in which the formation comprises one or more tabs (8).
4. A frame member as claimed in claim 3, in which the or each tab is square cut.
5. A frame member as claimed in claim 4, in which the or each tab is tapered to facilitate insertion into a complementary aperture in the adjacent frame member.
6. A frame member as claimed in any preceding claim, made of metal such as steel, aluminium or an alloy.
7. A frame member as claimed in any of claims I to 5, made of synthetic plastics material.
8. A method of making a frame member for the frame of a bicycle or the like characterised by the steps of taking a length of tube and forming at least one end of the tube with a complex curved shape (8). to abut an adjacent frame member (5) and with a formation (9) enabling that end to be located with respect to the adjacent frame member (5).
9. A method of making a frame member as claimed in claim 8, in which the at least one end is formed by means of a laser.
10. A method of making a frame member in which the laser is operated under programmed computer control.
Description:
A FRAME AND METHOD OF MAKING IT

The present invention relates to frames for bicycles tricycles and the like and to a method of making them.

Frame construction is labour intensive, time consuming and

therefore expensive. Each tube of the frame is specially formed at one or

both ends to fit the tube it abuts. These formations are complex and

difficult to produce with accuracy. Once formed the tubes must be held together, usually in a jig, so that they may be connected together, usually by welding. It is difficult to hold the tubes in the correct relative positions. Any inaccuracy in the formations can lead to difficulties in

fitting the tubes together for welding and to faults and stresses in the welds. It is an object of embodiments of the present invention to overcome or mitigate these difficulties.

According to one aspect of the present invention there is provided a frame member for the frame of a bicycle, tricycle or the like in which at least one end is shaped to abut an adjacent frame member and to produce a formation enabling that end to be located with respect to the adjacent

frame member.

According to another aspect of the present invention there is provided a method of making a frame member for the frame of a bicycle.

tricycle or the like including the steps of taking a length of tube and forming at least one end of the tube with a complex curved shape to abut an adjacent frame member and with a formation enabling that end to be located with respect to the adjacent frame member.

In a preferred embodiment of the invention, the shape of the end comprises a basic complex curve adapted to accept the complementary outer curved surface of the adjacent frame member. The formation

comprises one or more tabs. The or each tab may be square cut or tapered to facilitate insertion into a complementary aperture in the

adjacent frame member. The shaped end and formation are advantageously formed with a laser operating under programmed computer control. The frame member may be made of a metal, such as steel, aluminium, an alloy or titanium or a synthetic plastics material. Other holes may be formed in the frame member, for example to accept cable clips or other supports for water bottles and the like or to provide for drainage. Several frame members are assembled together to form a frame for a bicycle or tricycle. The formations and corresponding apertures into which they fit enable all the frame members to be positively accurately located with respect to each other prior to welding together of the members to connect them permanently together. If necessary, the frame members may be held in a jig during welding. The invention also comprises such completed bicycle and tricycle frames.

In order that the invention may be more clearly understood, one

embodiment thereof will now be described, by way of example, with

reference to the accompanying drawing, in which :*-*

Figure I shows a bicycle frame according to the invention,

Figure 2 is an exploded view of part of the frame of Figure I,

Figure 3 is an exploded view of another part of the frame of Figure I, and

Figure 4 is an exploded view of a further part of the frame of Figure I.

Referring to Figure I the frame comprises a head tube I, a top tube

2, a bottom bracket tube 3, a down tube 4, a seat tube 5 and rear forks

6. The tubes are formed by means of a programmable computer controlled laser. In one method of forming, each tube is cut by the laser from a continuous length of tube fed to the laser cutting machine. Thus the leading edge of the continuous tube is cut by the laser in the desired

formation. This formation usually comprises a basic complex curve in

which locating tabs are incorporated. In Figures 2,3 and 4, the complex curve is referenced 8 and the tabs are referenced 9. After the leading edge is cut, the continuous tube is advanced by the precise length of tube

required and the trailing edge of the length of tube is the cut by the laser

after any intermediate tab receiving apertures 10 are cut. Because of the

accuracy of the laser and the advance mechanism, the finished tube is extremely accurate. Post laser treatment of the cut ends will not normally be required. This contrasts with existing methods where burr removal after the initial forming is usually required. The laser may be programmed

to cut all the tubes required repeatedly. Repeat accuracy is extremely

high. Any other formations may also be cut by the laser in the tubes at the same time. Thus, drain holes, or holes to receive cable clips, water bottle supports and the like, may be made. Again post laser cut treatment will not normally be required. In an alternative method tubes may be cut to length and complex end formations formed subsequently. The tabs 9

may be square cut, or they may be tapered to facilitate their introduction into corresponding apertures 10. The tubes may be of metal, such as steel, aluminium, an alloy or titanium, or a synthetic plastics material.

Once all the tubes have been cut and/or formed as required they are assembled as shown in Figure I and permanently connected together by welding at the joints shown in Figures 2,3 and 4. Welds are indicated in Figure I at II. The accurate positioning of the tab receiving apertures I0 and the corresponding tabs 9 enables the tubes to be placed together extremely accurately for subsequent welding. No additional means may be necessary to maintain the tubes in the correct relative position during

welding thus simplifying the production process. Even if a jig is necessary to hold the tubes in the correct relative position, this may be

much simpler than currentiy used jigs. Furthermore, the cooperating tabs

and apertures 10, eliminate slippage between adjacent tubes during

welding which may occur with current systems.

It will be appreciated that the above embodiment has been

described by way of example only and that many variations are possible

without departing from the scope of the invention. Although two tabs

have been described at the end of the corresponding tube it may be

possible to reduce this to one thus further simplifying the production process. The tabs may be of any other suitable form to those described

above. They may, for example, be curved rather than square cut.