DE102017124162A1 - Metal bellows and method for producing a metal bellows - Google Patents

Abstract

A metal bellows (10), having a bellows wall (16) extending around a longitudinal axis (12) and enclosing a bellows interior (14), the bellows wall (16) having inner folds (18) and outer folds (20) which are provided via wall flanks (22 ) are connected with respect to a cost-effective production of a sufficiently durable and deformable metal bellows configured and further developed such that the inner folds (18) and / or the outer folds (20) are formed such that they each have an annular space (24, 25 )enclose.
A method for producing a metal bellows (10) is given.

Description

The invention relates to a metal bellows, having a bellows wall extending around a longitudinal axis and enclosing a bellows interior, the bellows wall having inner folds and outer folds which are connected to one another via wall flanks. In addition, the invention relates to a method for producing a metal bellows.

Metal bellows and methods for producing metal bellows are known from the prior art, wherein a construction of metal bellows is that a metal pipe is subjected to internal pressure and deformed into a metal bellows (bellows), such as in DE 20 2011 102 549 U1 described. As a result, metal bellows can be produced inexpensively. In another construction, a metal bellows is formed by a plurality of corrugated disks, wherein adjacent disks are alternately welded to each other on the inside and on the outside (membrane bellows), such as in DE 20 2013 007 501 U1 described. As a result, 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. In a diaphragm bellows is disadvantageous that its production by welding is structurally complex and therefore relatively expensive.

The invention has for its object to enable a cost-effective production of a sufficiently durable and deformable metal bellows.

The invention achieves the object by a metal bellows with the features of claim 1. Thereafter, the metal bellows is 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) each having an annular space.

In this way, a metal bellows is created, which has advantageous deformation properties, so large axial movements can be compensated and a high elongation and shortening (compression) can be achieved. This is achieved by virtue of the fact that the design of the inner folds and / or the outer folds with annular spaces reduces the loads acting on the folds, for example in the case of axial deformation (for example shortening). 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 the metal bellows 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 the advantages of a diaphragm 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 enclosing the annulus may have the shape of a loop, eyelet or the like in cross section. 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 bellows produced by hydroforming and subsequently deformed, in particular compressed.

The transition from adjacent wall flanks to a fold formed on these wall flanks, e.g. of two adjacent Wandungsflanken to an outer fold, is in particular designed such that portions of 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 wall flanks may form a line contact (e.g., circle) or a planar contact (e.g., circular ring) in the contact area.

These contact areas cause a limitation of the 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.

Specifically, the inner folds and outer folds are in particular continuously connected to each other, via intermediate transition edges. The distance between two adjacent wall flanks adjacent to an identical fold can also be referred to as a "division". Relative to the longitudinal axis, the inner fold is arranged radially inward and the outer fold is arranged radially on the outside (radial direction oriented orthogonally to the longitudinal axis). The inner fold forms a "valley". The outer fold forms a "mountain". An outer fold and the wall flanks adjacent to this outer fold form a corrugation. Along the longitudinal axis adjacent corrugations are interconnected via an inner fold.

Within the scope of a preferred embodiment, the inner folds and / or the outer folds can each directly enclose the annular space. 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 can be corrugated in the same direction or in opposite directions. As a result, the stability of the Wandungsflanken is increased. In addition, it is advantageous that, when the metal bellows is compressed, adjacent wall flanks can lie flat against one another, possibly over a large area. The Wandungsflanken may be formed in cross-section S-shaped or serpentine (meandering or reciprocating).

Conveniently, the Wandungsflanken can pass continuously 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 wall flanks and / or the folds in the form of predetermined breaking points can be avoided. In particular, the wall flanks and / or the folds are free of radial welds (weld seam along the longitudinal axis of the metal bellows can 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 annulus in the radial direction, a height (height of the annulus orthogonal to the longitudinal axis), which is less than 50 percent, preferably less than 30 percent, more preferably less than 20 percent, the height between outer fold and inner fold. As a result, a sufficient relief of the wrinkles can be achieved without restricting the production or the deformation of the metal bellows in operation too much.

• - Einlegen eines Metallrohrs (Halbzeug) in ein Formwerkzeug,
• - Verformen des Metallrohrs zu einem Metallbalg durch Beaufschlagen des Metallrohrinnenraums mit einem unter Druck stehenden Wirkmedium, wobei durch Zusammenwirken mit Formelementen des Formwerkzeugs Innenfalten, Außenfalten und Wandungsflanken des Metallbalgs ausgebildet werden, und
• - Stauchen des Metallbalgs entlang dessen Längsachse, wobei die Innenfalten und/oder die Außenfalten derart verformt werden, dass diese jeweils einen insbesondere geschlossenen Ringraum einschließen oder bilden.

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:

• Inserting a metal tube (semifinished product) into a mold,
• - Deforming of the metal tube to a metal bellows by applying the metal tube interior with a pressurized active medium, which are formed by cooperation with mold elements of the mold inner folds, outer folds and Wandungsflanken the metal bellows, and
• - Compressing the metal bellows along its longitudinal axis, wherein the inner folds and / or the outer folds are deformed such that they each include or form a particular closed annulus.

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

In the context of a preferred embodiment, during the deformation of the metal tube into a metal bellows, the wall flanks can be deformed such that they are corrugated in the same direction or in opposite directions. As a result, the corrugated structure is applied to the wall flanks in a structurally particularly favorable manner, with this application occurring together within only one work step. The corrugated structure increases the rigidity of the wall flanks.

Advantageously, the upsetting of the metal bellows can be effected by moving the shaped elements of the molding tool along the longitudinal axis of the metal bellows, in particular until the wall flanks and / or the shaped elements lie together on a block. As a result, a reliable application of features on the metal bellows is possible in one step, wherein the "lying on block" reliably signals the end of the deformation. 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 a preferred embodiment, the deformation of the metal tube to a metal bellows and the upsetting of the metal bellows can be carried out by the same mold. As a result, the cost-effective production of the metal bellows is favored again, since only a mold is needed and handling of the metal bellows for repositioning into another tool is not required. Throughput times, apparatus aids for Rearrangement and footprint in a production can be saved.

For further embodiment of the method for producing a metal bellows, the measures described in connection with the metal bellows can be used.

• 1 eine Ausführungsform des Metallbalgs in einer schematischen Schnittansicht (Teilschnitt).

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 an embodiment of the metal bellows in a schematic sectional view (partial section).

1 shows a metal bellows, in total with the reference numeral 10 is designated. The metal bellows 10 has a about a longitudinal axis 12 extending and a bellows interior 14 enclosing bellows wall 16 on. The bellows wall 16 has inner folds 18 and outer folds 20 on the wall edges 22 connected to each other.

The inner folds 18 and the outer folds 20 are shaped such that of the inner folds 18 and from the outer folds 20 one annulus each 24 . 25 is included. The along the longitudinal axis 12 oriented inboard distance 26 between two adjacent wall flanks 22 takes to the outside fold 20 So, starting from the inner fold 18 radially outward, initially from, to sections of Wandungsflanken 22 in a contact area 28 lie directly against each other and form a two-dimensional contact. In the annulus 24 takes the distance 26 again to. In other words, it follows an area in which adjacent wall edges 22 are spaced apart (spaced area 27 ), outward the contact area 28 and on it the annulus 24 ,

The same applies to the along the longitudinal axis 12 oriented external distance 29 between two adjacent wall flanks 22 , The external distance 29 decreases radially inward initially until sections of the wall flanks 22 in a contact area 28 ' lie directly against each other and form a two-dimensional contact. In the annulus 25 takes the distance 29 again to. In other words, it follows an area in which adjacent wall edges 22 are spaced apart (spaced area 27 ) inside the contact area 28 ' and on it the annulus 25 ,

In cross-section form the inner fold 18 and outer fold 20 one eyelet, loop or loop. An inner fold 18 forms a valley 30 , An outer fold 20 forms a mountain 32 , An outer fold 20 and to this outer fold 20 adjacent wall flanks 22 form a corrugation 34 , The outer folds 20 enclose the annulus 24 each immediately and completely. The inner folds 18 enclose the annulus 25 immediate and complete.

The wall flanks 22 are corrugated in the same direction. This means that the wall flanks 22 are so wavy that adjacent Wandungsflanken 22 in compression of the metal bellows 10 mostly abut each other. The wall flanks 22 have a serpentine profile in cross-section.

The wall flanks 22 , the inner folds 18 and the outer folds 20 go continuously into each other, so 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 points to the outer folds 20 a smaller wall thickness than at the inner folds 18 ,

The annulus 24 . 25 has in each case a height in the radial direction 36 in the present embodiment, less than 20 percent of the height between an outer fold 20 and the inner fold 18 is.

The method for producing a metal bellows 10 works as follows:

First, a metal tube welded in particular with a longitudinal seam, which is a semifinished product for a metal bellows still to be produced 10 represented in a mold (not shown) inserted (manual or mechanical insertion).

Subsequently, a deformation of the metal tube to a metal bellows 10 by subjecting the metal tube interior to a pressurized active medium, for example a water-oil mixture. By interaction with mold elements of the mold (not shown) become inner folds 18 , Outer folds 20 and wall flanks 22 the metal bellows 10 educated.

This is followed by a compression of the metal bellows 10 along its longitudinal axis 12 , where the inner folds 18 and the outer folds 20 be deformed such that these each have the inner annulus 24 . 25 lock in. The inner folds 18 , the outer folds 20 and / or the annulus 24 . 25 may have the properties already described above.

During deformation of the metal tube to a metal bellows 10 become the wall flanks 22 deformed such that they are corrugated in the same direction or in opposite directions (not shown). To Deformation show the wall flanks 22 in cross-section a serpentine shape.

The upsetting of the metal bellows 10 occurs in that the mold elements of the mold (not shown) along the longitudinal axis 12 the metal bellows 10 so moved and moved towards each other until the Wandungsflanken 22 and / or the shaped elements lie together on block.

Deforming the metal tube into a metal bellows 10 and the upsetting of the metal bellows 10 done by the same mold (not shown).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202011102549 U1 [0002]
• DE 202013007501 U1 [0002]

Claims (10)

Metal bellows (10), having a bellows wall (16) extending around a longitudinal axis (12) and enclosing a bellows interior (14), wherein the bellows wall (16) has inner folds (18) and outer folds (20) which extend over wall flanks (22). are interconnected, characterized in that the inner folds (18) and / or the outer folds (20) are shaped such that they each include an annular space (24, 25). Metal bellows (10) after Claim 1 , characterized in that the inner folds (18) and / or the outer folds (20) the annular space (24, 25) each directly enclose. Metal bellows (10) after Claim 1 or 2 , characterized in that the Wandungsflanken (22) are corrugated in the same direction or in opposite directions. Metal bellows (10) according to one of the preceding claims, characterized in that the wall flanks (22) merge continuously into the inner folds (18) and / or into the outer folds (20). Metal bellows (10) according to one of the preceding claims, characterized in that the bellows wall (16) at the outer folds (20) has a 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. Method for producing a metal bellows (10), in particular a metal bellows (10) according to one of the preceding claims, the method being characterized by the following steps: Inserting a metal tube into a mold, Deforming the metal tube into a metal bellows (10) by subjecting the metal tube interior to a pressurized active medium, inner folds (18), outer folds (20) and wall flanks (22) of the metal bellows (10) being formed by interaction with mold elements of the mold, and - Compression of the metal bellows (10) along its 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). Method according to Claim 7 , characterized in that during the 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. Method according to Claim 7 or 8th , characterized in that the upsetting of the metal bellows (10) takes place in that the mold elements of the mold 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 , Method according to 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.

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