WO1995034403A1

WO1995034403A1 - Bicycle frame with shrunk-fit elements

Info

Publication number: WO1995034403A1
Application number: PCT/DE1995/000796
Authority: WO
Inventors: Dieter Leibfried
Original assignee: Dieter Leibfried
Priority date: 1994-06-15
Filing date: 1995-06-14
Publication date: 1995-12-21
Also published as: DE4420772C2; DE4420772A1; AU2668895A

Abstract

A bicycle frame made of assembled frame elements (14) is produced by shrinkage fitting together the frame elements (14). A tube element (12) and a connecting sleeve (10) that form together an individual frame element (14) are interconnected by shrinkage-fitting techniques. The cooled tube element (12) is inserted into a heated tubular section (16) of the connecting sleeve (10). The inner surface (17) of a tubular section (16) of the connecting sleeve (10) lies on a free end of the tubular element (12) with a reduced outer diameter. Costly rework of the connecting points between connecting sleeve (10) and tubular element (12) may be dispensed with. The elements (14) of the assembled bicycle frame are therefore interconnected in a durable and reproducible manner by the connecting sleeves (10) and tube elements (12) without causing changes in the structure of the materials.

Description

Bicycle frame with shrink connections

The invention relates to a bicycle frame consisting of assembled frame elements which comprise pipe elements and pipe sleeves with pipe sections formed thereon which overlap the free ends of the pipe elements.

Such a frame construction has become known from EP 0 447 951 AI.

The manufacture of high quality frames, such as. it is used for racing bikes and mountain bikes, is characterized by the processing of high-quality pipes, the craftsmanship of the frame builder and the quality of the pipe sleeves.

The wall thickness of the pipes and the use of metal alloys and / or light metals are designed to minimize the frame weight and to optimize the stability of the frame construction.

The frame builder must find a satisfactory compromise between these extremes. Today soldering, welding, adhesive and screwing techniques are used to connect the frame elements, which are composed of pipe elements and pipe sleeves.

Screwing techniques have the advantage that non-weldable, light and high-strength alloys can be used. In the area of the saddle head, bottom bracket and steering head, the stability that can be achieved with screw connections is not sufficient to manufacture a frame that is designed to withstand the heavy loads that occur, for example, when riding on a mountain bike. Conventional frames are therefore usually welded or soldered today. But even the highest quality pipes become unstable if they are welded or soldered at too high temperatures or improperly. Local changes in the structure of the material occur during the welding process, which can reduce the strength of the frame at its most important connection points of the pipe elements with the pipe sleeves. Therefore, the frames produced in this way are complex and expensive to manufacture.

Therefore, further methods for connecting pipe elements and pipe sockets have been developed. EP 0 447 951 A1 shows a connection between tubes and nodes of tube frames, which comes about via an adhesive connection between press-fit surfaces. As a result, there can be no structural changes which impair the strength of the frame.

If, however, the pipe sleeve and the pipe element are pushed into one another, the surfaces coated with adhesive on both sides or on one side are pushed past one another and the adhesive is scraped off. Therefore, there is no reproducible adhesive connection. The frame manufactured according to EP 0 447 951 AI therefore already has a recess in the tubular element as an adhesive reservoir, so that the scraping off of the adhesive is counteracted. A process uncertainty in the formation of the adhesive connection remains.

Furthermore, metal surfaces of the parts to be connected, which have to be elaborately pretreated, are necessary in order to form metal adhesive connections, so that a permanently stable connection dung arises. Even a small amount of fat or moisture can cause a poor connection. Clean air conditions would therefore be necessary for mass production with sufficient process reliability for the process sequence. However, this would increase the manufacturing costs and nullify the profitability of such a production of bicycle frames.

The object of the present invention is to develop a bicycle frame in which pipe sleeves and pipe elements can be reproduced permanently without changing the structure of the materials.

The object is achieved in that the pipe elements are connected to the pipe sleeves via a shrink connection to a frame element.

The tube element is cooled by immersion in a nitrogen bath, so that it contracts easily and can be inserted into a heated tube section of the tube sleeve. After a temperature equalization between the pipe socket and the pipe element, a shrink or expansion fit occurs after insertion.

The type of connection has the advantage that there are no local structural changes which impair the strength of the material. Cracks due to material stresses can be avoided by not too strong temperature gradients.

It is also advantageous that the pipe sleeve and pipe element are permanently and permanently connected to each other. Due to shrinkage, the pipe sleeve and the pipe element made of light metal can be used, which are difficult to weld with difficulty. Therefore, on the one hand the weight minimization of the bicycle frame and on the other hand the stability and strength of the bicycle frame can be optimized.

It is also advantageous that the postprocessing of the transitions between the tubular sleeve and the tubular element or between different frame elements is omitted in the bicycle frame manufactured according to the invention. During the welding process, weld seams and surface unevenness arise, which have to be processed again. This can impair the stability of the connection point.

A disadvantage of a large number of welded bogies is that the tubular elements do not represent standard tubes. These pipe elements are drawn with a changing wall thickness, which increases towards the free ends of the pipe elements.

It is also advantageous that a plurality of frame elements are joined together to form a bicycle frame by means of a shrink connection.

Individual pipe elements and pipe sleeves can be joined to form a frame element, so that prepared different frame elements can be combined and assembled to form the bicycle frame according to the invention by means of a shrink connection.

In the bicycle frame according to the invention, all parts can be prepared and prepared so far that they only have to be put together and that afterwards the bicycle frame is finished except for a possible painting or surface coating.

It could also be advantageous to combine individual frame elements created by a shrink connection with other types of connection.

In a further preferred embodiment of the present invention, the pipe sleeves are made in one piece from a piece of material.

This gives the bicycle frame according to the invention a particular strength and stability.

It is also advantageous that the one-piece pipe sleeves are already designed as closure pieces for the triangular center piece of the bicycle frame.

If the pipe sections of the pipe sleeves have a shoulder on an inner wall, the pipe elements with a defined length can be inserted into the pipe sections of the pipe sleeves.

In a further preferred embodiment of the present invention, the inner surfaces of the pipe sections are machined to fit.

This has the advantage that the inner surface of the pipe sections of the pipe sleeve and the outer surface of the pipe elements lie exactly against one another. This makes a further contribution to increasing the stability of the bicycle frame according to the invention. In a further embodiment of the bicycle frame according to the invention, a sleeve can be inserted into the free end of the tubular element.

The sleeve or a solid core piece inserted as a press fit part in the free end of the tubular element. Therefore, this critical connection point between the pipe element and the pipe sleeve is given so much stability that thin standard pipes can be used which would otherwise not be usable. As a result, the weight of the bicycle frame according to the invention can be reduced even further.

If the free end of the pipe element is made with a reduced outer diameter, it can be inserted into the pipe section of the pipe sleeve in a defined and limited manner and there is no sharp heel edge which could lead to injuries in the event of a fall.

In a further embodiment of the bicycle frame according to the invention, the outer surface of the free end of the tubular element is machined to a good fit.

This advantageously leads to a tight fit of the outer surface of the free end of the pipe element on the counter surface, the inner surface of the pipe sections of the pipe sleeve. This enables a particularly stable shrink connection of the pipe sleeve and pipe element.

In a likewise particularly preferred embodiment, the rear frame of the bicycle frame can be removed.

The rear frame of the bicycle frame can be screwed on or on any other imaginable type can be attached to the bicycle frame. It can be attached to the rear triangle directly or via other connecting elements, for example a spring damper element.

The removable rear triangle has the advantage that the rear triangle, like a suspension fork, can be interchangeably combined with any bicycle frame elements to make a bicycle, e.g. a mountain bike, individually designed for the rider and route profile and adapted to it.

Brake sockets can advantageously be screwed onto the removable rear triangle.

This has the advantage that the brake bases for the brake elements can be replaced at any time, and the brake elements can already be fastened when the rear end is removed.

Taking into account weight minimization and stability, the frame elements can advantageously be made of metal and / or metal alloys.

When establishing the connection of frame elements, it is advantageous to proceed in such a way that the entire frame elements are pushed into one another and joined together at the same time.

This can be done particularly advantageously by means of a computer control, since the individual pipe elements must be joined together to form a triangle together with the pipe sections of the pipe sleeves. This requires that the individual pipe sections are pushed into one another exactly and in a coordinated manner. It must be noted that the individual elements do not tilt and / or lead to tension in the material. This is because the frame must not warp when the tube elements and tube sections are joined together. An error that arises during assembly cannot be corrected subsequently, since the connection is permanent and unsolvable due to shrinkage.

If the pipe elements are cooled below T = -120 ° during assembly, the pipe elements contract sufficiently to be inserted into pipe sections of the pipe sleeves.

If the pipe sleeves are heated up to T = 100 ° C., the pipe sections of the pipe sleeves expand in such a way that the pipe elements can advantageously be easily inserted and that the pipe elements in the assembled state overlap the pipe sections with the pipe sections.

It goes without saying that the pipe elements can also be heated, and that the pipe sleeves can be cooled in this case and that the pipe elements, when assembled, overlap the pipe sections with the pipe sections.

Further advantages result from the description of the attached drawing. Likewise, the features mentioned above and those listed further can be used according to the invention individually or in any combination with one another. The mentioned embodiments are not to be understood as a final list, but have rather exemplary character. The invention is shown in the drawing and is explained in more detail with reference to exemplary embodiments. It shows:

Fig. 1 shows a schematic section through one

Shrink connection made connection of pipe sleeve and pipe element;

2 shows a bicycle frame before being joined together by shrink connections;

3 shows a bicycle frame before being joined together by shrink connections with a removable rear;

4a shows a schematic representation of the connection between a removable rear and a bicycle frame according to the invention.

4b shows a further view of the connection according to FIG. 4a.

The figures of the drawing show the object according to the invention in a highly schematic manner and are not to be understood to scale. The physical features are shown in the individual figures so that the structure can be shown well.

1 shows a shrinkage connection between a pipe socket 10 and a pipe element 12, which together form the frame element 14. The pipe sleeve has an angled pipe section 16 into which the pipe element 12 is inserted. The tube section 16 has a shoulder 18 on an inner wall 17. The free end of the tubular element 12 is made with a reduced wall thickness, so that it is inserted into the tubular section 16 in a defined manner until it abuts the shoulder 18. In order to use thin wall thicknesses of the tubular element 12, a sleeve 19 is inserted into the free end of the tubular element 12 for reasons of stability.

To assemble the tubular element 12 and the sleeve 19 are worked to a press fit. During the shrinking process, the pipe sleeve 10 is heated to T = 100 °. The pipe sleeve 10 could also be heated to higher temperatures if necessary. It should be noted that the heating does not cause any structural changes, in particular no aging of the material.

It is also conceivable that the pipe element 12 is heated and that the pipe sleeve 10 is cooled.

After a temperature equalization, the pipe sleeve 10 and the pipe element 12 are permanently and permanently joined to form a frame element 14. It is no longer possible to heat or cool the pipe sleeve 10 and the pipe element 12 to different temperatures, so that they can be pulled apart by thermal expansion or thermal contraction. The frame element 14 can be combined with further frame elements to form a stable bicycle frame and can be joined together by further shrink connections.

2 shows frame elements which are joined together to form a bicycle frame 20 and can be completely fastened to one another by means of shrink connections. Pipe sleeves 10, 22, 23 can be joined together with pipe elements 12, 24, 26 and sleeves 19, 28, 30, 31, 32 to form a frame element. Likewise, the pipe sleeves 23, the sleeve 27 and the pipe element 24 alone can form a frame element. This also applies to further combinations of pipe elements, pipe sleeves and sleeves.

When assembling the frame elements to form a bicycle frame, the tube elements 12, 24, 26 cooled with liquid nitrogen are slowly and uniformly without tilting and without any material stress together with the likewise cooled sleeves 19, 28, 30, 31, 32 into the heated tube sections sections of the pipe sleeves 10, 22, 23 pushed. The frame elements thus together form a frame triangle to which a substructure can also be attached by shrinking.

The rear end includes a fork-shaped connecting element

33, which can accommodate tubular elements 34, 35. The connection of the connecting element 33 and the tubular elements 34, 35 is again possible by a shrink connection.

Brake bases 34 ', 35' are fastened to the tubular elements 34, 35. This is possible using a screw connection. The brake base 34 ', 35' could also on the tubular elements

34, 35 can be formed in one piece.

A fork-shaped connecting element 36 can be fastened to the pipe sleeve 23, to which in turn pipe elements 37, 38 with dropouts 39, 40 can be fastened by shrinking. In order that a triangular frame of the rear triangle can be formed without tilting and without bracing, the individual elements must be slowly and uniformly pushed into one another in a defined orientation. Since the interlocking requires precise work, this is advantageously done by computer controls (CAM) performed.

Fig. 3 shows frame elements which are joined together to form a bicycle frame 40 and can be fastened to one another by means of shrink connections. Pipe sleeves 10, 42, 43 can be joined together with pipe elements 12, 24, 26 and sleeves 19, 28, 30, 31, 32 to form a frame element.

Likewise, the tubular sleeve 43, the sleeve 27 and the tubular element 24 can already form a frame element. This also applies to all other combinations of pipe elements, pipe sleeves and sleeves.

When assembling the frame elements to form a bicycle frame, the tube elements 12, 24, 26 cooled with liquid nitrogen are slowly and evenly without tilting and without any material stress together with the likewise cooled sleeves 19, 28, 30, 31, 32 into the heated tube section sections of the pipe sleeves 10, 42, 43 pushed. The frame elements thus together form a frame triangle to which a removable rear triangle can be attached.

The pipe sleeves 42, 43 have connecting sections 44, 45 to which pipe elements 46, 47, 48, 59 can be screwed.

The screw connection is not shown in the figure.

The connection between the tubular elements and the pipe sleeves 42, 43 can also be achieved by another type of connection which makes it possible to remove the rear structure.

The dropouts 50, 51 are in the tubular elements 48, 49 and 46, 47 in turn shrinkable.

Brake bases 52, 53 can be attached to the tubular elements 46, 47.

So that the frame triangle can in turn be formed without tilting and without tensioning, the individual elements must be pushed into one another slowly and evenly. Since pushing one into the other requires precise work, this is again advantageously carried out under computer control (CAM).

FIG. 4a and FIG. 4b show the connection ^'between the Rohr¬ sleeve 42 and the tubular element 46. The free end of Verbin¬ extension portion 44 of the pipe sleeve 42 is formed as a solid body with a recess 55 into which a shoulder 56 of the tube member 46 can be used. The free end of the Rohrele¬ elementes 46 is also designed as a solid body, so that the connection between the pipe section 44 and the tubular element 46 can be stable.

A screw connection, which is not shown in the figure, gives the connection of pipe sleeve 42 and pipe element 46 the necessary resilient security. Other additional fastening means are also conceivable.

The recess 55 is designed like a dovetail so that the heel 56 can be inserted laterally and the connection is given a certain stability even when screwed together.

The type of connection between the pipe sleeve 42 and the tubular element 46 can also be between the pipe sleeve 43 and the Pipe elements 48, 49 come about. This also applies to the connection between the tubular element 47 and the tubular sleeve 42.

A bicycle frame, which consists of assembled frame elements 14, can be produced by shrinking the frame elements 14 together. A pipe element 12 and a pipe socket 10, which together form a single frame element 14, are connected to one another via shrinking techniques in that the cooled pipe element 12 is inserted into a heated pipe section 16 of the pipe socket 10. The inner surface 17 of a pipe section 16 of the pipe sleeve 10 lies against a free end of the pipe element 12 formed with a reduced outside diameter. Time-consuming reworking of the connection points between pipe sleeve 10 and pipe element 12 is eliminated. The assembled bicycle frame therefore has permanent connections of frame elements 14 through which pipe sleeves 10 and pipe elements 12 are reproducibly joined without structural changes in the materials.

Claims

Patent claims

1. Bicycle frame consisting of assembled frame elements (14), the tube elements (12; 24, 26, 34, 35, 37, 38) and tube sleeves (10; 22, 23; 42, 43) with tube sections formed thereon ( 16) which overlap the free ends of the tubular elements (12; 24, 26, 34, 35, 37, 38), characterized in that the tubular elements (12; 24, 26, 34, 35, 37, 38) are connected to the pipe sleeves (10; 22, 23; 42, 43) via a shrink connection to form a frame element (14).

2. Bicycle frame according to claim 1, characterized in that a plurality of frame elements (14) are joined together via a shrink connection to the bicycle frame.

3. Bicycle frame according to claim 1 or 2, characterized gekenn¬ characterized in that the pipe sleeves (10; 22, 23; 42, 43) are made in one piece from a material.

4. Bicycle frame according to one of claims 1 to 3, characterized in that the pipe sections (16) of the Rohr¬ sleeves (10; 22, 23; 42, 43) have a shoulder (18) on an inner wall.

5. Bicycle frame according to one of claims 1 to 4, characterized in that the inner surfaces of the Rohrab¬ sections (16) are machined to fit.

6. Bicycle frame according to one of claims 1 to 5, characterized in that in the free ends of the Rohrelemen- te (12; 24, 26, 34, 35, 37, 38) a sleeve (19, 27, 28, 30, 31, 32) can be used.

7. Bicycle frame according to one of claims 1 to 6, characterized in that the free ends of the tubular elements

(12; 24, 26, 34, 35, 37, 38) are made with a reduced outside diameter.

8. Bicycle frame according to one of claims 1 to 7, characterized in that the outer surfaces of the free end of the tubular elements (12; 24, 26, 34, -35, 37, 38) is machined to fit.

9. Bicycle frame according to one of claims 1 to 8, characterized in that the bicycle frame has a removable rear triangle.

10. Bicycle frame according to claim 9, characterized in that on the removable rear brake base (52, 53) can be screwed.

11. Bicycle frame according to claim 1 to 10, characterized gekenn¬ characterized in that the frame elements (14) are made of metal and / or metal alloys.

12. A method for producing the connection of Rahmenele¬ elements according to one of claims 1 to 11, characterized ge indicates that the entire frame elements (14) are pushed into one another and joined together.

13. A method for connecting frame elements according to claim 12, characterized in that the tubular elements (12; 24, 26, 34, 35, 37, 38) are cooled down under T = -120 ° C when joining them together with the pipe sleeves (10; 22, 23; 42, 43).

14. A method for connecting frame elements according to one of claims 12 or 13, characterized in that the pipe sleeves (10; 22, 23; 42, 43) when joining together with the pipe elements (12; 24, 26, 34, 35 , 37, 38) are heated to T = 100 ° C.