BE1021285B1 - IMPROVED METHOD - Google Patents

Abstract

The present invention relates to a method of manufacturing a membrane accumulator, comprising the steps of providing a first partial housing and a second partial housing; mounting a membrane in the first and / or the second partial housing; mounting the second partial housing on the first partial housing, whereby a closed housing is obtained which is divided by the membrane into two closed compartments, characterized in that the second partial housing is mounted on the first partial housing by means of Electro Magnetic Pulse (EMP) shrinking and / or welding to ensure gas and liquid tight assembly.

Description

Improved method

TECHNICAL DOMAIN

The invention relates to membrane accumulators such as used for example in hydraulic, pneumatic and hydro-pneumatic systems. In particular, the invention relates to a method for manufacturing membrane accumulators with the aid of electro-magnetic pulse (EMP) welding and / or shrinking.

BACKGROUND ART

A membrane accumulators is a gas and liquid tight vessel that is divided into compartments by a membrane. The membrane is hereby elastic so that the volumes or the mutual volume ratio of the compartments can change under the influence of a pressure difference between the compartments. Membrane accumulators are used in many fluid or hydro-pneumatic systems to store energy in the form of a compressed gas or liquid.

Membrane accumulators are highly suitable for controlling the pressure in a fluid system of e.g. pipelines, where a first compartment is typically connected to the system and contains the fluid, while a second compartment is filled with a gas, e.g. nitrogen, under pressure . With the aid of a membrane accumulators it is possible, among other things, to - compensate for pressure differences in the fluid system; - regulate the flow; - anticipating fluctuations in the demand for fluid; - to absorb pressure waves or pressure shocks, eg from a pump with a non-constant flow.

Membrane accumulators include a housing that in most cases is a composite of two parts, with at least one connection being provided for connection to a fluid system. They are often used in hydraulic systems to which they can return stored pressure when required. The connection then serves as the supply and / or discharge of the fluid from the hydraulic system. A membrane is mounted in the housing that divides the housing into a liquid compartment and a gas compartment.

Various embodiments of membrane accumulators and methods for manufacturing accumulators are already known in the art.

German patent DE 2 834 403 describes a membrane accumulator in which the top part is mounted on the bottom part by means of. a groove and an annular tongue on the bottom part in which the top part is clamped by radial and axial stresses. German application DE 10 2009 021463 describes an accumulator in which an outer housing and an inner housing fit together at the edges and are fixed to each other by deformation of the edges by the formation of a form seal. These documents describe examples of a mechanical manufacture in which two parts of the housing are mounted together by means of a screw thread and / or prestressed ring and / or mechanical deformation. Clamping the membrane can be achieved in various ways. The technology is bulky and expensive, and is only used for extremely high pressure requirements.

German application DE 2 139 367 describes a method for manufacturing an accumulator by welding the parts with the aid of an electron beam. This application gives an example of a technique in which a membrane accumulator is assembled from two halves, usually deep-drawn, preformed and machined, in which the membrane is mounted beforehand. The halves are welded together by means of the electro-beam welding technology. This process is tolerance sensitive and requires expensive preparation (turning off and on) of both halves. The connection is attached to the housing in a separate process. Although this technique is relatively expensive and slow due to the required preparation, it is probably the most commonly used technique.

Another known technique consists in closing a cylindrical pot around a connection after mounting the membrane. When the pot is closed, the seal of the membrane with respect to the housing is also provided. The housing and the connection are then made by means of a weld, gas-tightly connected. In terms of cost, this is a technically favorable technique, but it can only be applied with relatively low pressure requirements.

European patent EP 2 024 130 describes a method for manufacturing a pressure vessel using EMP welding. However, a pressure vessel as intended in this document must meet higher pressure requirements, and is simpler in construction due to the absence of a membrane and a possible connection to a fluid system. Furthermore, it should be noted that pressure vessels as referred to in this document are filled with a gas other than N2 (nitrogen) and fulfill a different function, so that they are loaded in a distinctive way than hydraulic accumulators. Hydraulic accumulators undergo a pulsating load, which means that the notch effect mentioned poses a significant risk. Moreover, the quality of the welding image of EMP welding is, in radial terms, insufficiently constant to exclude this risk. Avoiding a weld connection can therefore be desirable.

It is an object of the present invention to find a solution to at least some of the aforementioned problems.

There is a need for a membrane accumulator that meets high pressure requirements and can be manufactured in an efficient and relatively inexpensive manner. There is therefore a need for an improved method for manufacturing a membrane accumulator.

SUMMARY OF THE INVENTION

The invention relates to a method for manufacturing a membrane accumulator, which comprises the following steps: providing a first sub-housing, preferably a cylindrical sub-housing; providing a second sub-housing, preferably a cylindrical sub-housing; mounting a membrane in the first and / or the second sub-housing, preferably with the aid of a clamping ring; mounting the second sub-housing on the first sub-housing whereby a sealed housing is obtained which is divided by the membrane into two mutually closed compartments, wherein the second sub-housing is mounted on the first sub-housing by means of Electro Magnetic Pulse (EMP) crimping and / or Electro Magnetic

Pulse (EMP) welding to ensure gas and liquid tight assembly. Preferably, EMP shrinking is used.

In a second aspect the invention relates to a membrane accumulator provided with a first part housing, a second part housing, a membrane mounted in the first and / or second part housing, the second part housing being mounted on the first part housing so that a sealed housing is obtained which is the membrane is divided into two compartments that are mutually sealed, the second part housing being mounted gas-tight and liquid-tight on the first part housing by means of Electro Magnetic Pulse (EMP) crimping and / or Electro Magnetic Pulse (EMP) welding.

In a preferred embodiment, the first sub-housing comprises an edge with an overlap profile adapted to an edge of the second sub-housing and / or the second sub-housing comprises an edge with an overlap profile adapted to an edge of the first sub-housing.

In a preferred embodiment, the membrane is mounted with a clamping ring in the first or the second sub-housing. This clamping ring preferably has an overlap profile which is adapted to the first sub-housing and / or to the second sub-housing, preferably adapted to the edge of the first sub-housing and / or to the second sub-housing.

In a preferred embodiment, a sealing ring is mounted between the first and the second sub-housing to additionally ensure gas and liquid tight mounting.

In a preferred embodiment, after the EMP crimping and / or welding step, a weld, preferably a conventional weld such as a Mig weld, a Tig weld or an electrobeam weld, is arranged between the first and the second sub-housing around the gas and to ensure fluid-tight assembly even further. In this case the sealing ring can be omitted.

Thus, when manufacturing the membrane accumulator, two, preferably preformed, parts are brought together by EMP shrinking and / or welding as an alternative to electro-beam welding. Preferably, EMP shrinking is used. In addition to a few other mechanical advantages, this technology generates no or negligible heat input and the technology does not cause contamination, such as splashes that can damage and / or damage the membrane. This technique also provides the advantage that, viewed from the longitudinal direction of the accumulator, independently of the position of the welding zone, the membrane can be optimally mounted in the accumulator, e.g. in the center of the housing, so that the possible deformation in both directions is reduced. or more identical. This offers an optimum functioning of the membrane in the accumulator in function of the application.

DESCRIPTION OF THE FIGURES

Figure 1 is an illustration of a membrane accumulator before and after mounting by means of EMP crimping and / or welding according to the present invention wherein the second partial housing is disposed over the first partial housing.

Figure 2 is an illustration of a membrane accumulator before and after mounting by means of EMP crimping and / or welding according to the present invention wherein the second sub-housing is mounted in the first sub-housing.

Figure 3 is an illustration of a membrane accumulator before and after mounting by means of EMP welding according to the present invention wherein the second sub-housing with an edge with curled overlap profile is arranged in the first sub-housing.

DETAILED DESCRIPTION

The invention relates to a method for manufacturing membrane accumulators with the aid of electro-magnetic pulse (EMP) welding and / or shrinking, as well as a membrane accumulator which was manufactured by means of EMP welding and / or shrinking. When Electro Magnetic Pulse welding and / or shrinking is used, the two parts (6 & 7) are partially slid over each other and connected in the overlap zone (9).

Unless defined otherwise, all terms used in the description of the invention, including technical and scientific terms, have the meaning as generally understood by those skilled in the art of the invention. For a better assessment of the description of the invention, the following terms are explicitly explained. "A", "de" and "het" in this document refer to both the singular and the plural unless the context clearly assumes otherwise. For example, "a segment" means one or more than one segment.

When "about" or "round" is used in this document for a measurable quantity, a parameter, a duration or moment, and the like, variations are meant of +/- 20% or less, preferably +/- 10% or less, more preferably +/- 5% or less, even more preferably +/- 1% or less, and even more preferably +/- 0.1% or less than and of the quoted value, insofar as such variations of are applicable in the described invention. However, it must be understood here that the value of the quantity at which the term "about" or "round" is used is itself specifically disclosed.

The terms "include", "comprising", "consist of", "consisting of", "provided with", "contain", "containing", "include", "including", "contents", "contents" are synonyms and are inclusive or open terms indicating the presence of what follows, and which do not preclude or preclude the presence of other components, features, elements, members, steps, known from or described in the prior art.

The term "edge of the sub-housing" refers to the end of the sub-housing. This end is preferably substantially circular. Examples of what is understood by "edge" are indicated in the figures with references (6a) and (7a).

The term "overlap profile" refers to the shape of a sub-housing or the edge of a sub-housing in the vicinity of the connection of the first sub-housing to the second sub-housing and where the first and the second sub-housing connect closely together, preferably where the the first and second part housing touch each other. Preferably, the first and / or the second sub-housing comprises an overlap profile before mounting that promotes gas and liquid tightness after mounting. The overlap profile of the partial housings can be distorted by the assembly process. Unless clearly meant otherwise, the term "overlap profile" in this text means the profile of a sub-housing before mounting the second sub-housing on the first sub-housing. Examples of what is meant by "overlap profile" are indicated in the figures with references (9a) and (9b).

The terms "first part housing" and "second part housing" refer to the two parts that are mounted on top of each other to form one sealed housing. Preferably, the first sub-housing is adapted to be in contact with a liquid and the second sub-housing is adapted to be in contact with a gas, preferably a pressurized gas.

The citation of numerical intervals by the end points includes all integers, fractions and / or real numbers between the end points, including these end points.

In a first aspect the invention relates to a method for manufacturing a membrane accumulator as described in claims 1 and 7. In a second aspect the invention relates to a membrane accumulator as described in claim 10.

As already indicated, the invention relates to a method in which no or negligible heat input is generated and in which no contamination is caused, such as splashes which can attack and / or damage the membrane. The method also provides the advantage that, viewed from the longitudinal direction of the accumulator, independently of the position of the welding or shrinking zone, the membrane can be optimally mounted in the accumulator, e.g. in the center of the housing, so that the deformation of the membrane that is possible in both directions is more or less identical. The invention therefore also relates to an improved membrane accumulator in which the position of the membrane is selected independently of the position of the welding or crimping zone.

The method also offers some mechanical advantages, including:

Two different materials (eg selected from steel, stainless steel, aluminum, ...) can be combined, eg first sub housing from stainless steel and second sub housing from aluminum.

The material has a minimal "spring-back" in the deformed and thus sealing zone. This is perhaps the most important and distinguishing feature with respect to other applied, whether or not protected, mechanical closing techniques such as roll or press molds.

The thinning of the wall thickness for the purpose of positioning and / or mounting of the membrane and / or the clamping ring has no adverse consequences, since the thinning can be compensated by overlapping parts of the two part housings.

It is possible to laminate the least distorted part (6) with the aim of increasing the wall thickness and thus reinforcing the wall. The maximum wall thickness to be deformed, for example, is estimated at 3 to 4 mm for steel with the current state of the art.

There is the possibility of (over) shrinking an additional locking ring (8) at the level of the clamping zone.

The mechanical properties of the material are not affected by high temperatures, eg high melting or welding temperatures.

There are also a number of other advantages associated with the method and the membrane accumulator as described in this document, including:

It is an energy-friendly process without the addition of filling and / or melting materials.

The cost price of welding or shrinking is a fraction of other, more conventional welding processes such as MIG / MAG / TIG welding, electrobeam welding,

Considerably less preparation is required and preparation of the deformed deep-drawing parts (6, 7) is simpler due to the limited tolerance requirements. - Due to the limited loss of material in the overlap zone, no or only minimal material compensation is required to maintain a minimum wall thickness in the connection zone. This leads to material and weight savings. On the other hand, the overlap and any supporting ring (11) and / or locking ring (8) can lead to an increase in weight and material used. Depending on the application and requirements, it is therefore possible to make a choice between the various embodiments described in this document.

According to an embodiment, the second sub-housing is mounted on the first sub-housing by means of EMP crimping to circumvent some disadvantages of EMP welding. Advantages of EMP shrinking over welding can be the following:

There is a greatly reduced risk of notching due to high pulse or shock loads.

The quality control of the assembly is simpler and / or cheaper.

No fusion occurs at the molecular level between the sub-housings.

In a preferred embodiment, the first sub-housing comprises an edge with an overlap profile adapted to an edge of the second sub-housing and / or the second sub-housing comprises an edge with an overlap profile adapted to an edge of the first sub-housing.

According to a preferred embodiment, the membrane is inserted into the first (7) or the second sub-housing (6) with a clamping ring (10), preferably in the first sub-housing (7) and preferably before the second sub-housing is mounted on the first sub-housing. The diaphragm is mounted with a clamping ring in the first or the second part housing. This clamping ring preferably has an overlap profile which is adapted to the first sub-housing and / or to the second sub-housing, preferably adapted to the edge of the first sub-housing and / or to the second sub-housing.

Since there is no "fusion" in the overlap zone when using EMP shrinking, it may be necessary to provide both a gas seal and a mechanical connection. This can be achieved in various ways, as illustrated in Figures 1 to 3.

In a preferred embodiment, a support ring (11) is introduced to compensate for undesired deformation of the inner wall of the first and / or second sub-housing due to impact forces.

In a preferred embodiment, a locking ring (8) is arranged around the first and the second sub-housing in an overlap zone. This locking ring can be provided, for example, by first heating it up, for example via induction, whereby the locking ring expands, then placing the locking ring over the partial housings in the overlap zone, and then cooling or cooling the locking ring afterwards so that the locking ring is clamped over the sub-housings. The circlip can preferably be provided by means of the same EMP crimping and / or welding technology that is used to mount the second part housing on the first part housing.

The circlip is fitted on the outside and at the level of the overlap zone. The circlip serves to ensure the gas and / or liquid tightness of the housing, particularly when the membrane accumulator is used in a high pressure application. Applying the locking ring via EMP shrinking and / or welding can be done at the same time as or after mounting the second part housing on the first part housing. This is preferably done at the same time, i.e. the mounting of the locking ring and the mounting of the second sub-housing on the first sub-housing takes place in the same assembly step.

In a preferred embodiment, the membrane accumulator is resistant to maximum pressures of at least 20 bar, preferably at least 40 bar, more preferably at least 70 bar, even more preferably at least 100 bar, even more preferably at least 200 bar, even more preferably at least 300 bar.

In a preferred embodiment, the parameters of the components of the membrane accumulator and / or the parameters of the EMP shrink and / or weld are selected as a function of the pressure requirements of the membrane accumulator. The different parameters that can play a role here are:

The choice of materials of the components, such as the first and second partial housing, the membrane, the locking ring, the clamping ring, the locking ring;

The thickness, shape, diameter or curvature of the components.

The size, orientation and time-dependent profile of the magnetic field that is generated with the EMP shrink and / or weld.

In a preferred embodiment, the membrane accumulator is provided with a clamping ring in the first and / or second partial housing which clampes the membrane.

In a preferred embodiment the membrane accumulator is provided with a support ring in the first and the second sub-housing arranged at the level of an overlap zone between the first and the second sub-housing.

In a preferred embodiment the membrane accumulator is provided with a locking ring over the first and second sub-housing at the level of the overlap zone between the first and the second sub-housing.

In a further aspect the invention relates to a membrane accumulator comprising a first sub-housing, a second sub-housing and a membrane, wherein the second sub-housing is mounted on the first sub-housing in an overlap zone whereby a housing is obtained which comprises a longitudinal direction, wherein the membrane in the housing is mounted and divides the housing into two compartments, the position of the membrane in the longitudinal direction of the housing being determined independently of the position of the welding zone.

The described method that uses Electro Magnetic Pulse shrinking and / or welding, and in particular EMP shrinking, makes it possible to obtain optimum technical results with relatively simple principles, and this at a lower cost price than known techniques.

In the following, the invention is described a.d.h.v. non-limiting examples illustrating the invention, and which are not intended or may be interpreted to limit the scope of the invention.

In Figure 1 the half cross-section of a membrane accumulator is illustrated before (100) and after (101) mounting by means of. EMP crimping and / or welding according to the present invention wherein the second part housing (6) is arranged over the first part housing (7). The membrane accumulator is substantially cylindrical-symmetrical about the axis (20).

In Figure 2 the half section of a membrane accumulator is illustrated before (200) and after (201) mounting by means of. EMP crimping and / or welding according to the present invention wherein the second part housing (6) is arranged in the first part housing (7). The membrane accumulator is substantially cylindrical-symmetrical about the axis (20).

In Figure 3 the half cross-section of a membrane accumulator is illustrated before (300) and after (301) mounting by means of. EMP welding according to the present invention wherein the second part housing (6) is arranged in the first part housing (7). The membrane accumulator is substantially cylindrical-symmetrical about the axis (20). The edge (6a) of the second partial housing (6) comprises a curled overlap profile (9b).

The diaphragm accumulator comprises a housing (1) composed of sub-housings (6, 7) with a connection (2) which is mounted here on the housing with a thread, whereby a diaphragm (3) is mounted in a sub-housing (7) the membrane separating the liquid compartment (4) from the gas compartment (5).

The housing (1) is usually manufactured from metal, for example stainless steel, steel, aluminum or a combination thereof. The diaphragm must be mounted before closing the housing. Examples of how the membrane can be mounted are illustrated in Figs. 1 to 3 for (alternatives 102-105 and 110 in fig. 1, alternatives 202-205, 210, 212 and 214 in fig. 2, alternatives 302-303 in fig. 3) the assembly of the second part housing (6) on the first sub housing (7) and after (alternatives 106-109 and 111 in fig. 1, alternatives 206-209, 211, 213 and 215 in fig. 2, alternatives 306-307 in fig. 3). The different alternatives illustrate some different possibilities for the profile of the edges (6a, 7a) of the sub-housings (6, 7), the overlap profiles (9a, 9b) in the overlap zone (9) and the profile of the support ring (11) , clamping ring (10), locking ring (8) and sealing ring (14).

Alternatives (110), (111), (212) and (213) show an example of an overlap profile (9a, 9b) of the first part housing (Fig. 1, reference 9a) or of the second part housing (Fig. 2, reference) 9b) comprising a recess (13). By EMP welding or shrinking, this recess is at least partially filled by respectively a part of the edge of the second part housing (Fig. 1) or the first part housing (Fig. 2), which is deformed by the EMP welding or shrinking. The recess (13) can be made, for example, by injection molding, preferably when the partial housing with the recess is made of aluminum. The recess (13) can also be made, for example, by milling or turning out.

Alternatives (214) and (215) illustrate an overlap profile according to an embodiment of the present invention, wherein no sealing ring (14) is provided, but where a weld (13) is provided between first and second sub-housing, at the height of the end of the edge of the partial housing that sits over the other partial housing. In this case the weld (13) is at the height of the end of the edge (7a) of the first sub-housing. The weld can be applied via eg Mig or Tig welding. This weld that is applied afterwards when the sub-housings are already mounted on each other via the EMP crimping and / or welding, is easier to apply than a weld to mount two sub-housings on top of each other as used in the prior art.

Figure 3 shows some alternative embodiments of the present invention wherein the edges (6a) of the second sub-housing (6) comprise a, preferably outwardly curled, overlap profile (9b). Such an overlap profile makes it possible to absorb the impact of the EMP welding on the sub housing with the curled profile on the outside, i.e. on the outside of the membrane accumulator. Alternatives (303) and (307) illustrate an embodiment in which the overlap profile (9b) of the edge (6a) of the second housing (6) comprises a shape that clamps the membrane (3) against the overlap profile (9a) of the edge (9a) 7a) of the first partial housing (7). Figure 3 illustrates an embodiment of the present invention wherein the sub housing is mounted on top of each other via EMP welding. Hereby it is possible to omit the sealing ring, since the weld in itself ensures sufficient gas and liquid tight assembly.

The alternatives illustrated in the figures do not constitute an exhaustive list. Moreover, it is also assumed that the present invention is not limited to the embodiments described above and that some modifications or changes can be added to the described examples without re-evaluating the appended claims. Thus it is stated in this text that the second sub-housing is or is mounted on the first sub-housing, but it will be clear that, for example, the first sub-housing can also be mounted on the second sub-housing. M.a.w. the orientation of the sub-housings (e.g. the first sub-housing above, below or next to the second sub-housing) or the order of assembly (e.g. first provide the first sub-housing and then mount the second sub-housing on it) may vary depending on the version.

Claims (16)

CONCLUSIONS A method for manufacturing a membrane accumulator, comprising the steps of: providing a first sub-housing, preferably a cylindrical sub-housing; providing a second sub-housing, preferably a cylindrical sub-housing; mounting a membrane in the first and / or the second sub-housing; mounting the second sub-housing on the first sub-housing, whereby a sealed housing is obtained which is divided by the membrane into two mutually closed compartments, characterized in that the second sub-housing is mounted on the first sub-housing by means of Electro Magnetic Pulse (EMP) shrink to ensure gas and liquid tight assembly. A method as in claim 1, wherein the first sub-housing comprises an edge with an overlap profile adapted to an edge of the second sub-housing and / or wherein the second sub-housing comprises an edge with an overlap profile adapted to an edge of the first partial housing. A method as in any one of claims 1 to 2, wherein the membrane is mounted with a clamping ring in the first or the second sub-housing. Method as in claim 3, wherein the clamping ring comprises an overlap profile that is adapted to the first sub-housing and / or to the second sub-housing, wherein the overlap profile is adapted to the edge of the first sub-housing and / or to the edge of the second partial housing. A method as in any one of claims 1 to 4, wherein a support ring (11) is inserted into the first and / or second sub-housing. A method as in any one of claims 1 to 5, wherein a locking ring (8) is arranged around the first and the second sub-housing in an overlap zone. A method for manufacturing a membrane accumulator, comprising the following steps: providing a first sub-housing, preferably a cylindrical sub-housing; providing a second sub-housing, preferably a cylindrical sub-housing; mounting a membrane in the first and / or the second sub-housing; mounting the second sub-housing on the first sub-housing, whereby a sealed housing is obtained which is divided by the membrane into two mutually closed compartments, characterized in that the second sub-housing is mounted on the first sub-housing by means of Electro Magnetic Pulse (EMP) welding to ensure gas-tight and liquid-tight assembly. A method as in claim 7, wherein the first sub-housing comprises an edge with an overlap profile adapted to an edge of the second sub-housing and / or wherein the second sub-housing comprises an edge with an overlap profile adapted to an edge of the first partial housing. A method as in any one of claims 7 to 8, wherein the diaphragm is mounted with a clamping ring in the first or the second part housing, wherein preferably the clamping ring comprises an overlap profile adapted to the first part housing and / or to the second part housing , wherein the overlap profile is adapted to the edge of the first sub-housing and / or to the edge of the second sub-housing, and / or wherein a support ring (11) is inserted into the first and / or second sub-housing and / or wherein a locking ring ( 8) is arranged around the first and the second sub-housing in an overlap zone. 10. A membrane accumulator provided with a first sub-housing, a second sub-housing, a membrane mounted in the first and / or the second sub-housing, the second sub-housing being mounted on the first sub-housing so that a sealed housing is distributed which is distributed by the membrane in two separate compartments, characterized in that the second sub-housing is mounted gas-tight and liquid-tight on the first sub-housing by means of Electro Magnetic Pulse (EMP) crimping and / or Welding Electro Magnetic Pulse (EMP). A membrane accumulator as claimed in claim 10, provided with a clamping ring in the first and / or second part housing which clampes the membrane, provided with a support ring in the first and the second part housing arranged at the level of an overlap zone between the first and the second partial housing, and / or provided with a locking ring over the first and second partial housing at the level of the overlap zone between the first and the second partial housing. A membrane accumulator as in claim 10 comprising a pressure resistance of at least 20 bar. A membrane accumulator as in any of claims 10 to 12, wherein components of the membrane accumulator such as the first sub-housing, the second sub-housing, the membrane, the clamping ring, the support ring and / or the locking ring, comprise parameters whose values are selected are dependent on pressure requirements, whereby one or more parameters can be selected from the following list: material of the component; and / or thickness, shape, diameter and / or curvature of the components; A membrane accumulator as in any one of claims 10 to 13, wherein the EMP includes crimping and / or welding parameters whose values are selected as a function of pressure requirements, wherein one or more parameters can be selected from the list of size, orientation and / or the time-dependent profile of a magnetic field that is generated during EMP shrinking and / or welding. A membrane accumulator as in any one of claims 10 to 14, wherein the second sub housing is mounted on the first sub housing according to a method as in one of claims 1 to 9. A membrane accumulator comprising a first sub-housing, a second sub-housing and a membrane, wherein the second sub-housing is mounted on the first sub-housing in an overlap zone, thereby obtaining a housing comprising a longitudinal direction, the membrane being mounted in the housing and divides the housing into two compartments, the position of the membrane in the longitudinal direction of the housing being determined independently of the position of the welding zone