EP0788848A1 - Method of manufacturing a tube with variable cross-section - Google Patents

Abstract

The method consists of making a tube which has sections of different cross sectional configuration. A sheet metal blank (14) is prepared in one piece, with a rectangular base region (11') and at least one reshaped section (15). The base region is converted into a tubular shape, and the reshaped section is converted into a spiral shape. The final shaping of the tube is then carried out, and the butting edges (17,17',18,18',19,19') are joined together. At least some places on the butting edges (17,17') which lie in the base region, may also be joined before the final shaping stage.

Description

The invention relates to a method for producing a tube with sections of different cross-sectional configurations.

Welded tubes are formed from steel strip or blanks into tubes and then welded along their joints. This creates hollow bodies with a round cross-section.

Pipes with cross-sectional extensions at the ends are often required. These widenings are produced by mechanical widening, in that the pipe end is widened with the aid of a mandrel by tensile and / or compressive forces. The cross-sectional extensions that can be achieved are however limited by the deformability of the material used. Accordingly, only comparatively small changes in geometry can be made. The expansion of the material structure in the expansion area frequently also occurs as a result of the expansion. This is undesirable in many cases because the hardening reduces the material's ability to change shape. A complex annealing treatment is then necessary to eliminate the structural change in order to ensure a ductility of the widened pipe ends that is sufficient for subsequent processing steps.

Additional effort is also required if the pipes have to be equipped with holders, brackets or the like. Such attachments are usually fixed to the pipe by welding. Not only is this associated with additional production engineering effort, but it can also result in subsequent structural changes of the material in the welding area as a result of the welding.

Based on the prior art, the invention is based on the object of making a method for producing a tube with sections of different cross-sectional configuration simpler and more economical, in particular also improving the possibilities in the design of the tube configuration.

This object is achieved according to the invention by the method characterized in claim 1.

To produce a tube with sections of different cross-sectional configurations, a board is first provided, which has a rectangular base region, on the at least one forming section is integrated in one piece. The circuit board is the true-to-length development of the outer circumferential surface of the pipe to be produced, including any surfaces that protrude over the circumference of the pipe as tabs or the like.

In the next step, the board is formed into a hollow cylindrical body. This involves a tubular shaping of the base area and a spiral shaping of the shaping section. The longitudinal edges of the base area then lie exactly against one another, while the blank is wound up in the forming section with partially overlapping areas.

This forming process can be carried out economically and with high accuracy in a die, the blank being first made into a semicircular profile in a first partial step and into the hollow cylindrical shape in a further partial step.

This is followed by the final shaping of the tube, in which the shaping section is acted on by means of suitable active media and the final geometry of the tube is thus achieved.

The final shaping can be a widening of the forming section with an active medium acting from the inside, for example a mandrel. If a tab projecting from the circumference of the tube is to be formed, the shaping section only needs to be directed into the corresponding position.

The joints are connected in the subsequent joining process. This is usually done by welding. Various methods are available for this, such as laser, shielding gas, inductive or resistance welding.

With the method according to the invention, a tube with sections of different cross-sectional configurations is obtained, harmful deformations or weakening of the tube material being avoided in the area of a cross-sectional change or occurring only to an acceptable extent.

According to the features of claim 2, it is also possible to join the abutting edges lying in the base region in whole or in part before the final shaping is carried out. With a more complicated geometric configuration of a tube, this can facilitate the further production steps.

The method according to the invention is particularly well suited for the production of a tube with a frustoconical cross-sectional widening at at least one end.

A circuit board with a rectangular base region is then used, which is followed at one end by a shaping section of a trapezoidal configuration. The circuit board is symmetrical along its longitudinal plane. The board is the development of the outer surface of the pipe to be manufactured.

After the blank has been formed into a tubular hollow body, the final shaping of the tube is carried out by expanding the spiral-shaped forming section in a trumpet-like manner. This is expediently done in a suitable die by thorning out the end region so that it unwinds completely and the final geometry of the stepped tube is achieved. This is followed by the welding of the butt edges.

With this procedure, almost any cross-sectional enlargements can be achieved in the end areas of a pipe. The deformability of the material used limits the shape of the pipes considerably less than before. Solidifications of the material in the area of the widening are minimized. As a result, there is usually no need for thermal aftertreatment to equalize adverse material changes.

An advantageous development of the method according to the invention can be seen in claim 4. A wide geometry variation of the end regions of a tube is possible through the use of a circuit board, in which further trapezoidal and / or rectangular forming sections follow the trapezoidal forming section.

In this way, pipes can be produced in which further cylindrical or frustoconical sections adjoin the region expanded in the manner of a trumpet.

In order to avoid that the abutting edges of the forming section abut one another directly during the rolling-up process, a ramp-like sliding area can be assigned to the forming section. This is particularly advantageous if several forming sections of different geometries are linked together.

A sliding area can be formed, for example, by providing a short trapezoidal extension as an auxiliary surface at the front end of the board. This auxiliary surface ensures that a problem-free rolling up of the board is possible due to the initially point-like contact.

However, it is also possible to design the sliding area by changing over on a butt edge of a forming section.

A further advantageous measure according to claim 6 is that the blank is provided with blank thicknesses which change in certain regions in the rolling direction before the forming by a specific rolling deformation. If necessary, the rolled blank is trimmed as required before it is sent for further processing. The use-specifically shaped board has deliberately varying board thicknesses, in order to convey various areas precisely to the wall thicknesses corresponding to the later use of the tube made from the board, which are matched to the respective loads and thus also the locally differing voltage peaks that these areas have in practice Subject to use.

In this way, a pipe can be produced with sections of different cross-sectional configuration and sections of different wall thickness. The area-reduced wall thickness is particularly suitable for the production of components that are under external stress, but in which the stresses that occur due to the component design are distributed over the component at different heights. This is often the case, in particular, with components of motor vehicles. If such components are designed according to the maximum load, this inevitably leads to oversizing in less stressed areas. This not only results in a higher use of materials, but also in unnecessary weight. These disadvantages are now avoided in that the pipes used to manufacture the components correspond to the later ones Load in different areas of the components can be dimensioned differently.

In principle, the rolling direction can be adapted to the particular configuration of the later pipe. The starting boards can also be partially rolled twice or, if necessary, several times in different directions. As a result, the respective thickness can also be varied in stages as required. The rolling is expediently carried out in a two-roll stand. By varying the roller geometry in the roller inlet, the symmetry with respect to the central transverse plane can be influenced within certain limits.

Figur 1

in der Draufsicht den Ausschnitt einer Platine für ein endseitig erweitertes Rohr;

Figur 2

einen vertikalen Querschnitt durch einen spiralförmig gerollten Umformabschnitt;

Figur 3

einen vertikalen Querschnitt durch den rohrförmig gerollten Mittelabschnitt;

Figur 4

in der Draufsicht den Endabschnitt eines Rohrs mit einem kegelstumpfförmigen Längenabschnitt, an den sich ein zylinderförmiger Längenabschnitt anschließt, sowie die Abwicklung des Endabschnitts;

Figur 5

eine weitere Ausführungsform einer Platine;

Figur 6

einen vertikalen Querschnitt durch einen Umformabschnitt mit einer Umstellung;

Figur 7

den Endabschnitt eines mehrfach abgesetzten Rohrs;

Figur 8

eine weitere Ausführungsform eines Rohrs in der Draufsicht;

Figur 9

das Rohr gemäß Figur 8 in perspektivischer Darstellung;

Figur 10

einen vertikalen Querschnitt durch das Rohr der Figur 8 vor der Endformgebung;

Figur 11

den vertikalen Querschnitt durch das Rohr gemäß der Figur 8 nach der Endformgebung und

Figur 12

in perspektivischer Darstellungsweise einen Ausschnitt aus einer Platine mit bereichsweise unterschiedlichen Platinendicken.

The invention is described in more detail below with reference to exemplary embodiments shown in the drawings. Show it:

Figure 1

in the top view the section of a circuit board for a tube expanded at the end;

Figure 2

a vertical cross section through a spirally rolled forming section;

Figure 3

a vertical cross section through the tubular rolled middle section;

Figure 4

in plan view the end section of a tube with a frustoconical length section, which is followed by a cylindrical length section, and the development of the end section;

Figure 5

another embodiment of a circuit board;

Figure 6

a vertical cross section through a forming section with a change;

Figure 7

the end section of a multi-step pipe;

Figure 8

a further embodiment of a tube in plan view;

Figure 9

the tube of Figure 8 in perspective;

Figure 10

a vertical cross section through the tube of Figure 8 before final shaping;

Figure 11

the vertical cross section through the tube according to Figure 8 after the final shaping and

Figure 12

a perspective view of a section of a board with different board thicknesses in some areas.

FIG. 1 shows a section of a circuit board 1 which is used to produce a tube which is expanded at the end. The circuit board 1 has a rectangular base region 2, which is followed by a trapezoidal forming section 3. The plate 1 is symmetrical with respect to its central longitudinal axis MLA and represents the true-to-length development of the pipe to be produced.

Technically, the blank 1 is formed into a hollow cylindrical body. The forming section 3 is rolled up in a spiral, as shown in FIG. 2. Here there is an overlap of the forming section 3 in the areas 4 and 5.

It can be seen from FIG. 3 that the base region 2 is formed into a tubular shape. The longitudinal edges 6 and 7 of the base region 2 are then opposite one another.

In the final shaping, the hollow cylindrical body is fixed in a suitable die and the forming section 3 is thorned out, whereby it is converted into the final frustoconical geometry. Due to the blank cut precisely adapted to the tube shape, an exact contact of the longitudinal edges 8 and 9 of the forming section 3 and the longitudinal edges 6, 7 of the base region 2 is achieved.

In a subsequent process step, the tube is finished by welding the longitudinal edges 6, 7 or 8, 9.

FIG. 4 shows the end section of a tube 10 with a cylindrical middle section 11, which is followed by a frustoconical length section 12 and a cylindrical length section 13.

The tube 10 is formed symmetrically to the central longitudinal axis MLA.

The circuit board 14, which is used to manufacture the tube 10, is shown in dashed lines. The circuit board 14 is the development of the lateral surface of the tube 10. The rectangular base region 11 'can be seen, to which a trapezoidal forming section 15 and another rectangular forming section 16 are connected. Due to the adapted blank cut an exact contact of the joints 17, 17 ', 18, 18', 19, 19 'on the end-shaped tube 10 is achieved.

5 shows a circuit board 20 with a rectangular base region 21 and a trapezoidal one formed forming section 22 and a further rectangular forming section 23. In order to avoid that the abutting edges 24, 25 of the forming section 23 abut against one another during the rolling-up process, a ramp-like sliding area 26 is formed. The sliding area 26 is formed by a short trapezoidal extension 27. The approach 27 acts as an auxiliary surface and ensures that the roll-up process of the circuit board 20 can take place without problems due to the initially point-like contact.

Another solution to support the reeling process is shown in FIG. 6. Here, a sliding area 28 is realized by a changeover 29 on a butt edge 30 of a forming section 31.

With the method according to the invention, pipes with sections of different cross-sectional configurations can be produced in a simple and economical manner. The number of paragraphs can vary depending on the application. Such a pipe 32 with multiple shoulders is shown in FIG. A shoulder 34, consisting of a frustoconical transition section 35 and a cylindrical longitudinal section 36, adjoins the cylindrical central section 33. Another shoulder 37 is formed by the frustoconical length section 38 and the cylindrical length section 39.

FIGS. 8 to 11 show a tube 40 with a holder 42 protruding from the circumference 41. The holder 42 is arranged in the middle region 43 of the tube 40.

During manufacture, a board with a rectangular base region, to which the holder 42 is attached as a forming section 44, is again assumed. The board is then rolled up, so that the situation shown in Figure 10 results. The forming section 44 is in some areas on the outer surface 45 of the tube 40. For the final shaping, the shaping section 44 is brought into the desired position in a suitable manner, so that the holder 42 results.

The longitudinal edges 46 and 47 are then welded.

FIG. 12 shows a section of a blank 48, in which areas 49 to 52 have been stretched by a specific rolling deformation, with blank thicknesses s ₁ to s ₄ changing in the rolling direction WR. In the transitions 53, 54, 55, the areas 49-52 merge seamlessly into one another. In the representation chosen here, the circuit board 48 has an approximately smooth surface 57 on the underside 56. Of course, the board 48 can also be stretched on both sides.

The areas 50-52 are part of a rectangular base area 58 of the circuit board 48. The area 49 has a trapezoidal configuration and forms the shaping section 59, which is integrally attached to the base area 58.

A tube can be produced from the board 48 with sections of different cross-sectional configurations and sections of different wall thicknesses s ₁ to s ₄ . In the case of the circuit board 48 which is deformed specifically for use, the regions 49-52 have exactly those circuit board thicknesses s ₁ to s ₄ which are matched to the respective loads and tensions to which the regions 49-52 are subject in the practical use of the tube produced from the circuit board 48 .

List of reference symbols

1 -

circuit board

2 -

Base area v. 1

3 -

Forming section

4 -

Area v. 3rd

5 -

Area v. 3rd

6 -

Long edge of 2nd

7 -

Long edge of 2nd

8th -

Long edge of 3rd

9 -

Long edge of 3rd

10 -

pipe

11 -

Middle section v. 10th
11 'base area

12 -

Longitudinal section v. 10th

13 -

Longitudinal section v. 10th

14 -

circuit board

15 -

Forming section

16 -

Forming section

17 -

Shock
17 'kick

18 -

Shock
18 'stroke

19 -

Shock
19 'kick

20 -

circuit board

21 -

Base area

22 -

Forming section

23 -

Forming section

24 -

Butt edge

25 -

Butt edge

26 -

Sliding area

27 -

approach

28 -

Sliding area

29 -

Changeover

30 -

Butt edge

31 -

Forming section

32 -

pipe

33 -

Middle section

34 -

paragraph

35 -

Transition section

36 -

Length section

37 -

paragraph

38 -

Length section

39 -

Length section

40 -

pipe

41 -

Scope of 40

42 -

holder

43 -

Middle range

44 -

Forming section

45 -

Mantle surface v. 40

46 -

Long edge

47 -

Long edge

48 -

circuit board

49 -

Area v. 48

50 -

Area v. 48

51 -

Area v. 48

52 -

Area v. 48

53 -

crossing

54 -

crossing

55 -

crossing

56 -

Bottom v. 48

57 -

Surface v. 48

58 -

Base area

59 -

Forming section

MLA

Central longitudinal axis

s ₁ -

Board thickness v. 49

s ₂ -

Board thickness v. 50

s ₃ -

Board thickness v. 51

s ₄ -

Board thickness v. 52

WR -

Rolling direction

Claims (6)

Process for the production of a pipe with sections of different cross-sectional configurations, characterized by the following measures: a) providing a circuit board (1, 14, 20, 48) with a rectangular base region (2, 11 ', 21, 43), to which at least one forming section (3, 15, 44, 59) is integrally attached, b) tubular shaping of the base region (2, 11 ', 21, 43) and spiral shaping of the shaping section (3, 15, 44, 59), c) final shaping of the tube, d) Joining the butt edges (6, 7, 8, 9, 17, 17 ', 18, 18'. 19, 19 ', 46, 47). Method according to Claim 1, characterized in that the abutting edges (6, 7, 17, 17 ') in the base region are joined at least in regions before the final shaping. Method according to claim 1 or 2 for the production of a tube with a frustoconical cross-sectional widening at at least one end, characterized by the use of a plate (1, 14, 21) with a forming section (3, 15, 22) of a trapezoidal configuration one end and symmetrical formation along its central longitudinal axis (MLA). Method according to claim 3, characterized by the use of a circuit board (14, 21) in which further trapezoidal and / or rectangular forming sections (16, 23) follow the trapezoidal forming section (15, 22). Method according to one of claims 1 to 4, characterized in that the forming section (23, 31) is assigned a ramp-like sliding area (26, 28). Method according to one of claims 1 to 5, characterized in that prior to the shaping of the blank (48) there is a targeted rolling deformation of the blank (48) with blank thicknesses (s ₁ -s ₄ ) which change in certain regions in the rolling direction (WR).

Images