EP3698072A1

EP3698072A1 - Metal bellows and method for producing a metal bellows

Info

Publication number: EP3698072A1
Application number: EP18792386.7A
Authority: EP
Inventors: Andreas Schill
Original assignee: Boa Metal Solutions GmbH
Current assignee: Boa Metal Solutions GmbH
Priority date: 2017-10-17
Filing date: 2018-10-17
Publication date: 2020-08-26
Also published as: WO2019076987A1; DE102017124162A1

Abstract

The invention relates to a metal bellows (10), comprising a bellows wall (16), which extends around a longitudinal axis (12) and encloses a bellows interior (14), the bellows wall (16) having inner folds (18) and outer folds (20), which are connected to each other by means of wall flanks (22). Said metal bellows is designed and developed in such a way, with a view to the economical production of a sufficiently durable and deformable metal bellows, that the inner folds (18) and/or the outer folds (20) are formed in such a way that said folds each enclose an annular space (24, 25). The invention further relates to a method for producing a metal bellows (10).

Description

Title: Metal bellows and method of making a metal bellows

The invention relates to a metal bellows, having a bellows wall extending around a longitudinal axis and enclosing a bellows interior, wherein the bellows wall

Inside folds and outside folds has over

Wandungsflanken are interconnected. In addition, the invention relates to a method for producing a

Metal bellows.

Metal bellows and methods for producing metal bellows are known in the art, wherein a construction of Metallbälgen is that a metal tube through Applied internal pressure and is deformed into a metal bellows (bellows), as described for example in DE 20 2011 102 549 Ul. This allows metal bellows

produce economically. In another construction, a metal bellows is formed by a plurality of corrugated discs, wherein adjacent discs are alternately welded together on the inside and on the outside (membrane bellows), as described for example in DE 20 2013 007 501 Ul. This can be better

Deformation properties of the bellows, for example. Higher possible elongations can be achieved.

In a bellows is disadvantageous that its

Deformation, for example, its elongation, and its

Durability are relatively limited. At a

Membrane bellows is disadvantageous in that its manufacture by welding structurally complex and therefore

is relatively expensive. The invention is based on the object

To allow inexpensive production of a sufficiently durable and deformable metal bellows.

The invention solves the problem by a metal bellows with the features of claim 1. Thereafter, the distinguished

Metal bellows characterized in that the inner folds and / or the outer folds are shaped such that they include in each case in the radial end regions (fold end region) in each case an annular space. In this way, a metal bellows is created, the

has advantageous deformation properties, so large axial movements can be compensated and a high elongation and shortening (compression) can be achieved. This succeeds due to the fact that the design of the

Inner folds and / or the outer folds with annular spaces the loads acting on the folds, for example, in axial

Deformation (e.g., shortening) are reduced. This has advantages when using the metal bellows, as improved durability can be achieved. In addition, by the wrinkles with annular spaces, a cost-effective production of

Metallbalgs by hydroforming (often called "hydroforming") and upsetting of the metal bellows allows, as damage to the folds can be avoided. In other words, the proposed metal bellows in its use has the advantages of

Membran bellows, but is cheaper to produce. The inner pleats may also be referred to as "inner pleats" and the outer pleats may also be referred to as "outer pleats".

The fold, which encloses the annulus, can in the

Cross-section in the form of a loop, eyelet or the like. The annular space can not exclusively, for example. Sectionally, have a circular, elliptical or oval cross-section. In this case, symmetrical or asymmetrical embodiments are possible. The present metal bellows are, in particular, a material produced by hydroforming and subsequently deformed, in particular compressed,

Bellows. The transition from adjacent wall flanks to a fold formed on these wall flanks, for example from two adjacent wall flanks to form an outer fold, is in particular designed such that sections

adjacent Wandungsflanken lie directly against each other (contact area). This contact region is located on the side of the annulus facing this wall flanks. Due to the direct concern of the annulus is closed. The

adjacent sidewalls can have a line contact (e.g., circle) or a flat one in the contact area

Forming contact (e.g., annulus).

These contact areas cause a limitation of

Bending load on each of the Wandungsflanken radially opposite boundaries of the annular spaces of the inner and outer folds by deflecting the bellows-axial movements in a rolling of the mutually adjacent Wandungsflanken each other.

In concrete terms are the inner folds and outer folds

in particular continuously connected to each other, via intermediate conversion edges. The distance

between two adjacent wall flanks adjacent to an identical fold can also be referred to as "division"

be designated. Relative to the longitudinal axis is the

Inner fold radially inward and the outer fold radially outwardly arranged (radial direction orthogonal to the longitudinal axis oriented). The inner fold forms a "valley"

Outside fold forms a "mountain." An outside fold and the on this outer fold adjacent Wandungsflanken form a corrugation. Along the longitudinal axis adjacent corrugations are interconnected via an inner fold. Within the scope of a preferred embodiment, the

Inside folds and / or the outer folds enclose the annulus immediately. This means that the walls of the folds border directly on the annular spaces. As a result, a structurally simple design of the folds without further components is possible (outer fold / inner fold and / or annulus free of other components). In addition, the inner folds and / or the outer folds in particular completely enclose the annular space in each case. This also contributes to a structurally simple design.

Advantageously, the wall flanks

be corrugated in the same direction or in opposite directions. As a result, the stability of the Wandungsflanken is increased. In addition, from

Advantage that when compression of the metal bellows adjacent wall flanks surface, possibly over a large area, can abut each other. The Wandungsflanken may be formed in cross-section S-shaped or serpentine (meandering or reciprocating). Conveniently, the Wandungsflanken

continuously merge into the inner folds and / or the outer folds. In other words, the wall flanks and the outer folds and / or the inner folds can be formed in one piece. Thus, a weakening of the

Wandungsflanken and / or the folds in the form of Predetermined breaking points are avoided. In particular, the wall flanks and / or the folds are free of radial

Welds (weld along the longitudinal axis of the

Metal bellows may be present).

In concrete terms, the bellows wall can have a smaller wall thickness at the outer folds than at the inner folds.

As a result, the bellows wall, in particular due to the hydroforming at the outer folds elastic than at the inner folds, wherein the design of the outer folds with annular spaces protects the outer folds from overloading.

In a preferred embodiment, the annular space in the radial direction, a height (height of the annular space

orthogonal to the longitudinal axis) which is less than 50 percent, preferably less than 30 percent, more preferably less than 20 percent, of the height between outer fold and inner fold. As a result, a sufficient relief of the wrinkles can be achieved without the

Production or deformation of the metal bellows in operation too restrictive.

The object mentioned at the outset is also achieved by a method for producing a metal bellows, in particular a metal bellows as described above. Thereafter, the metal bellows is characterized by the following steps:

- Insert a metal tube (semi-finished) in a

Mold

- Deforming of the metal tube to a metal bellows

Apply metal pipe interior with an under Compressive active medium, which are formed by interaction with mold elements of the mold inner folds, outer folds and Wandungsflanken of Metallbalgs, and - upsetting the metal bellows along the longitudinal axis, wherein the inner folds and / or the outer folds are deformed such that they each include a particular closed annulus or form.

With regard to the achievable with the method advantages, reference is made to the above statements to the metal bellows.

As part of a preferred embodiment, during the deformation of the metal tube to a metal bellows, the Wandungsflanken be deformed such that this

corrugated in the same direction or in opposite directions. As a result, the corrugated structure is applied to the Wandungsflanken in a structurally particularly favorable manner, this

Applying together within just one

Work step takes place. The corrugated structure increases the rigidity of the wall flanks.

Advantageously, the upsetting of the metal bellows can take place in that the shaped elements of the mold are moved along the longitudinal axis of the metal bellows, in particular until the wall flanks and / or the

Form elements lie together on block. As a result, a reliable application of features on the metal bellows is possible in one step, wherein the "on block" reliably the end of the deformation signaled. In other words, the mold elements of the mold along the longitudinal axis of the metal bellows are moved towards each other until the wall flanks and / or the form elements are together on block and further compression of the metal bellows is not possible. In this case, a mold is located between two wall flanks, which are connected to each other via an inner fold or an outer fold. In the context of a preferred embodiment, the

Deforming of the metal tube to a metal bellows and the upsetting of the metal bellows by the same mold done. As a result, the cost-effective production of the metal bellows is again favored because only one

Mold needed and handling of the metal bellows for repositioning in another tool is not required. Throughput times, equipment aids for rearrangement and footprint in a production can be saved.

For further embodiment of the method for producing a metal bellows, in connection with the

Metal bellows described measures serve. The invention will be explained in more detail below with reference to the figure, wherein identical or functionally identical elements are partially provided only once with reference numerals. Show it : 1 shows an embodiment of the metal bellows in a schematic sectional view (partial section).

Figure 1 shows a metal bellows, the total with the

Reference numeral 10 is designated. The metal bellows 10 has a bellows wall 16 extending around a longitudinal axis 12 and enclosing a bellows interior 14. The bellows wall 16 has inner folds 18 and outer folds 20, which are connected to each other via Wandungsflanken 22.

The inner pleats 18 and the outer pleats 20 are shaped so that of the inner pleats 18 and of the

Outer folds 20 each have an annular space 24, 25 is included. The oriented along the longitudinal axis 12

internal distance 26 between two adjacent

Wandungsflanken 22 takes to the outer fold 20, so starting from the inner fold 18 radially outward, initially from, until sections of the Wandungsflanken 22 in a contact region 28 directly abut each other and form a flat contact. In the annular space 24, the distance 26 increases again. In other words, it follows an area in which

adjacent Wandungsflanken 22 are spaced apart (spaced area 27), outwardly the contact area

28 and then the annulus 24.

The same applies to the along the longitudinal axis 12 oriented outer distance 29 between two adjacent Wandungsflanken 22. The outer distance

29 initially decreases radially inward, until sections of the wall flanks 22 in a contact region 28 'directly abut each other and form a two-dimensional contact. In the annular space 25, the distance 29 increases again. In other words, it follows an area where neighboring ones

Wandungsflanken 22 are spaced from each other

(Spaced area 27) inwardly the contact area 28 'and then the annulus 25th

In cross section, the inner fold 18 and outer fold 20 each form an eyelet, loop or loop. A

Inner fold 18 forms a valley 30. An outer fold 20 forms a mountain 32. An outer fold 20 and the to this

Outer fold 20 adjacent wall flanks 22 form a corrugation 34. The outer folds 20 surround the annulus 24 respectively immediately and completely. The inner folds 18 enclose the annular space 25 directly and completely.

The wall flanks 22 are corrugated in the same direction. This means that the wall flanks 22 are corrugated in such a way that adjacent wall flanks 22 for the most part abut one another upon compression of the metal bellows 10. The

Wandungsflanken 22 have in cross section

serpentine profile.

The Wandungsflanken 22, the inner folds 18 and the

Outer folds 20 continuously merge into each other, so they are integrally formed. The wall flanks 22, the inner folds 18 and / or the outer folds 20 are thus free of radial welds. The bellows wall 16 has a smaller wall thickness at the outer folds 20 than at the inner folds 18. The annular space 24, 25 has in the radial direction in each case a height 36, which is less than 20 percent of the height between an outer fold 20 and the inner fold 18 in the present embodiment.

The method for producing a metal bellows 10 works as follows: First, a particular with a longitudinal seam

welded metal tube, which is a semi-finished for a still to be manufactured metal bellows 10, in a mold (not shown) inserted (manual or mechanical insertion).

Subsequently, a deformation of the metal tube to a metal bellows 10 by applying the metal tube interior with a pressurized active medium, such as a water-oil mixture. Through interaction with

Forming elements of the molding tool (not shown), inner folds 18, outer folds 20 and wall flanks 22 of the metal bellows 10 are formed.

This is followed by a compression of the metal bellows 10 along its longitudinal axis 12, wherein the inner folds 18 and the outer folds 20 are deformed such that they each include the inner annular space 24, 25. The

Inner pleats 18, the outer pleats 20 and / or the annular space 24, 25 may be those already described above

Have properties. During deformation of the metal tube to a metal bellows 10, the Wandungsflanken 22 are deformed such that they are corrugated in the same direction or in opposite directions (not shown). After deformation, the wall flanks 22 have a serpentine shape in cross-section.

The upsetting of the metal bellows 10 takes place in that the shaping elements of the molding tool (not shown) are moved along the longitudinal axis 12 of the metal bellows 10 and moved toward one another until the wall flanks 22 and / or the shaped elements lie together on a block.

The deformation of the metal tube to a metal bellows 10 and the upsetting of the metal bellows 10 by the same mold (not shown).

Claims

claims

1. metal bellows (10), with a about a longitudinal axis (12) extending and a bellows interior (14) enclosing Balgwandung (16), wherein the Balgwandung (16) inner folds (18) and outer folds (20) which over Wandungsflanken ( 22) are interconnected, characterized in that the inner folds (18) and / or the outer folds (20) are formed such that they each include an annular space (24, 25).

2. metal bellows (10) according to claim 1, characterized

in that the inner folds (18) and / or the outer folds (20) respectively directly surround the annular space (24, 25).

3. metal bellows (10) according to claim 1 or 2, characterized

characterized in that the wall flanks (22)

corrugated in the same direction or in opposite directions.

4. metal bellows (10) according to one of the preceding

Claims, characterized in that the

Wandungsflanken (22) continuously in the

Go inside folds (18) and / or in the outer folds (20).

5. metal bellows (10) according to one of the preceding

Claims, characterized in that the

Balgwandung (16) on the outer folds (20) a has smaller wall thickness than at the inner folds (18).

Metal bellows (10) according to one of the preceding

Claims, characterized in that the annular space (24, 25) in the radial direction has a height (36) which is less than 50 percent, preferably less than 30 percent, more preferably less than 20

Percent, the height between outer fold (20) and

Inner fold (18) is. 7. Method for producing a metal bellows (10),

in particular a metal bellows (10) according to any one of the preceding claims, wherein the method is characterized by the following steps:

Inserting a metal tube into a mold,

- Deformation of the metal tube to a metal bellows (10) by applying the metal tube interior with a pressurized active medium, wherein

Cooperation with mold elements of the mold inner folds (18), outer folds (20) and Wandungsflanken (22) of the metal bellows (10) are formed, and

- upsetting the metal bellows (10) along its

The longitudinal axis (12), wherein the inner folds (18) and / or the outer folds (20) are deformed such that they each include an annular space (24, 25).

A method according to claim 7, characterized in that during the deformation of the metal tube to a metal bellows (10) the Wandungsflanken (22) in such a way be deformed, that this in the same direction or

are corrugated in opposite directions.

9. The method according to claim 7 or 8, characterized

characterized in that the upsetting of the metal bellows (10) takes place in that the molded elements of the

Forming tool along the longitudinal axis (12) of the

Metal bellows (10) are moved, in particular until the Wandungsflanken (22) and / or the form elements lie together on block.

10. The method according to any one of claims 7 to 9, characterized in that the deformation of the metal tube to a metal bellows (10) and the upsetting of the metal bellows (10) carried by the same mold.