METHOD FOR PRODUCING A CONNECTION BETWEEN TWO METALLIC COMPONENTS

Abstract

The invention relates to a method for producing a connection between a first metallic component (2) and a second metallic component (3), wherein at least one of the two metallic components (2, 3) is powder-metallurgically manufactured from a sintering material and the connection is produced by means of soldering in a connection area (4) formed between the two metallic components (2, 3). The surface (9), which forms a part of the connection area (4), of the metallic component (2 or 3) manufactured from the sintering material is compacted prior to the soldering.

Claims

1. A method for producing a connection between a first metallic component (2) and a second metallic component (3), wherein at least one of the two metallic components (2, 3) is manufactured powder-metallurgically from a sintering material and the connection is produced by means of soldering in a connection area (4) formed between the two metallic components (2, 3), wherein the surface (9), which forms a part of the connection area (4), of the metallic component (2 or 3) manufactured from the sintering material is compacted prior to the soldering.

2. The method according to claim 1, wherein the compaction of the surface (9), which forms a part of the connection area (4), of the component (2 or 3) manufactured powder-metallurgically from a sintering material is carried out to a density of at least 99.5% of the full material density.

3. The method according to claim 1, wherein the compaction of the surface (9), which forms a part of the connection area (4), of the component (2 or 3) manufactured powder-metallurgically from a sintering material is carried out by means of blasting.

4. The method according to claim 3, wherein for blasting, a powder of stainless steel manufactured by means of gas atomization is used as blasting medium.

5. The method according to claim 1, wherein a sintering powder of stainless steel is used as sintering material.

6. The method according to claim 1, wherein a copper solder is used as solder.

7. An assembly (1) comprising a first metallic component (2) and a second metallic component (3), wherein at least one of the two metallic components (2, 3) is manufactured powder-metallurgically from a sintering material, and the two components (2, 3) are soldered to one another with a solder (5) in a connection area (4), wherein the metallic component, which is manufactured from the sintering material, is surface-compacted in the connection area (4).

8. The assembly (1) according to claim 7, wherein the metallic component (2 or 3), which is manufactured from the sintering material, comprises a surface density of at least 99.5% of the full material density in the connection area (4).

9. The assembly (1) according to claim 7, wherein the metallic component (2 or 3), which is manufactured from the sintering material, comprises a compacted layer, having a layer thickness (10) of between 50 m and 350 m, in the connection area (4).

10. The assembly (1) according to claim 7, wherein the metallic component (2 or 3), which is manufactured from the sintering material, comprises a fraction of solder of at most 0.1 vol % in the connection area (4).

Description

[0017] For the purpose of better understanding of the invention, it will be elucidated in more detail by means of the figures below.

[0018] These show in a respectively very simplified schematic representation:

[0019] FIG. 1 a sectional view of an assembly of two metallic components;

[0020] FIG. 2 an enlarged detail of the assembly according to FIG. 1.

[0021] First of all, it is to be noted that in the different embodiments described, equal parts are provided with equal reference numbers and/or equal component designations, where the disclosures contained in the entire description may be analogously transferred to equal parts with equal reference numbers and/or equal component designations. Moreover, the specifications of location, such as at the top, at the bottom, at the side, chosen in the description refer to the directly described and depicted figure and in case of a change of position, these specifications of location are to be analogously transferred to the new position.

[0022] FIG. 1 shows an embodiment variant of an assembly 1, comprising and/or consisting of a first metallic component 2 and a second metallic component 3. At least one of the two components 2, 3 is manufactured powder-metallurgically from a sintering material. In the depicted embodiment variant, this is the first metallic component 2, which is a mounting element for the second metallic component 3, in particular a screw neck, for which it comprises a bore extending continuously in the direction of the longitudinal central axis for taking in a connection element, in particular a screw. The second metallic component 3 is a pipeline, for example a fuel line, in the depicted embodiment variant. Moreover, the second metallic component 3 or in general the component not manufactured powder-metallurgically (if not both metallic components 2, 3 are powder-metallurgically manufactured from a sintering material) can for example be a cast part, in particular consist of steel.

[0023] The assembly 1 or its metallic components 2, 3 can also be provided for a different application, for example for exhaust systems or lubricant pipes in plant construction.

[0024] The first metallic component 2 is connected to the second metallic component 3 by soldering. For this purpose, a connection area 4 (a joint gap) is formed between the two metallic components 2, 3, into which a solder 5 is taken in with which the materially bonded connection between the two metallic components 2, 3 is produced, as can better be seen from FIG. 2 showing the connection area 4 in larger representation.

[0025] It is to be noted at this point that the first metallic component 2 comprises an indentation for the partial intake of the second metallic component 3, as can be seen from FIGS. 1 and 2. In particular, this recess comprises a bending, which at least approximately corresponds to the bending of the second metallic component 3. However, the connection area 4 can also have a shape different from the one represented in FIGS. 1 and 2.

[0026] The first metallic component 2, or in general the powder-metallurgically manufactured component, can be manufactured according to a common sintering method. As said method is per se known, it is merely mentioned in this regard that this method comprises the steps of powder blending, powder compaction to a green compact, single- or multi-level sintering and optionally mechanical post-processing, such as deburring. The parameters that are to be used respectively are inter alia guided by the powder that is used and are known to the person skilled in the art, such that at this point, for the avoidance of repetitions, reference is made to the prior art in this regard.

[0027] Below, reference is made to a powder-metallurgically manufactured component, i.e. a sintered component, only. This also covers the first metallic component 2.

[0028] Subsequently to sintering, it is provided for that the powder-metallurgically manufactured component is compacted in the connection area 4. In principle, the compaction can also be performed more widely, such that not only a surface area 6 of the sintered component in the connection area 4 is compacted, but also adjacent areas. However, this is not obligatorily required for the formation of the connection between the two metallic components 2, 3, as no solder 5 is applied onto these sites.

[0029] The compaction of the surface area 6 of the powder-metallurgically manufactured component can be carried out according to different methods, for example pressing or rolling.

[0030] However, in the preferred embodiment variant of the method, the compaction is carried out by means of blasting of a blasting medium. By means of blasting, in addition to the compaction, by means of the cold working of the surface an increase in the hardness of the powder-metallurgically manufactured component can be achieved in this area.

[0031] For example scrap particles, gravel, etc. can be used as blasting medium. The particles of the blasting medium may have an elongated shape, a needle-like shape, an irregular shape, a polygonal shape, a round shape, an oval shape, etc.

[0032] However, particularly preferred, a steel powder of stainless steel manufactured by means of gas atomization is used as blasting medium for the aforementioned reasons.

[0033] The particles of the blasting medium can have a particle diameter selected from a range of 0.2 mm to 2 mm. In this regard, the particle diameter is that diameter of a sphere, into which the particle just fits.

[0034] The blasting medium can comprise particles of a particle size distribution between 0.2 mm and 2 mm. This can for example be provided by using one or several grading curve(s).

[0035] By the compaction of the surface area 6 of the powder-metallurgically manufactured component, a density that amounts to at least 95% of the full material density, however, at least 99.5% of the full material density according to an embodiment variant, may be achieved in this area. In this regard, the full material density is that density which the component would have in the connection area 4 if it were a void-free cast component, i.e. in other words the density of a pore-free component.

[0036] Particularly preferred, the surface area 6 has a density of at least 99.9% of the full material density. In particular, the density of the powder-metallurgically manufactured component in the surface area 6 forming a part of the connection area 4 amounts to 100% of the full material density. This is adumbrated in FIG. 2 by the surface area 6 not having any pores 7 which only occur below a dashed line 8 marking the end of the surface area 6.

[0037] The compacted surface area 6 extends from an outer surface 9, which forms a part of the connection area 4, of the powder-metallurgically manufactured component into a depth below this surface 9 amounting to at least 50 m. It is preferably provided for according to an embodiment variant that the compacted surface area 6 comprises a layer thickness 10 amounting to between 50 m and 350 m, in particular between 100 m and 150 m. Such a high layer thickness of the compacted area can be achieved in particular by using the aforementioned steel powder manufactured according to a gas atomization method.

[0038] For manufacturing the powder-metallurgically manufactured component, a known metal powder (mixture) can be used. However, preferably, a steel powder is used, in particular a steel powder from a stainless steel or high-grade steel. The steel powder can for example have the composition 0 wt. % to 20 wt. % nickel, 1 wt. % to 25 wt. % chromium, 0 wt. % to 20 wt. % molybdenum, balance: iron. For example, the powder can comprise 18.5 wt. % Cr, 11.2 wt. % Ni, balance iron (oxygen maximum 0.22 wt. %, nitrogen maximum 0.05 wt. %, carbon maximum 0.02 wt. %). The common processing aids, such as compacting auxiliaries etc., as are per se known, can be admixed to the powder.

[0039] It is further possible that alloys with low melting points, such as tin alloys, are used as the solder 5. However, according to a further embodiment variant, a copper solder is particularly preferred. In this regard, the term copper solder also comprises copper alloys that can be used as the solder 5.

[0040] The solder 5 can for example be applied as a paste onto the first and/or the second metallic component 2, 3. For a higher degree of automation, the solder 5 can at least partially be applied onto at least one of the two metallic components 2, 3 outside of the connection area 4. By heating the solder 5 at least to the melting temperature, for example in a continuous furnace, the solder 5 can flow into the connection area 4 and form the connection between the two metallic components 2, 3 after cooling. For this purpose, the two metallic components 2, 3 are correspondingly positioned to one another and held with a holding device, in particular already before the application of the solder 5.

[0041] According to a further embodiment variant, it can be provided for that the metallic component, which is manufactured from the sintering material, in the connection area 4 in the surface area 6 comprises a fraction of solder of at most 0.1 vol %, in particular of 0 vol %.

[0042] Preferably, the powder-metallurgically manufactured component is cleaned after the compaction, in particular blasting compaction, and prior to the soldering. Cleaning is in particular carried out by means of thermal cleaning in an H.sub.2 atmosphere. This cleaning serves the purpose of freeing the surface of the component from oxides as far as possible. A temperature of between 800 C. and 1200 C. is suggested for carrying out this cleaning.

[0043] Tests have been carried out for evaluating the connection quality. For this purpose, two metallic components 2, 3 connected to one another by means of a copper solder were clamped and the breaking force was measured. One of the two components consisted of a cast steel, the other one of a steel powder which was processed powder-metallurgically. For measuring the breaking force, the force acting onto the connection area 4 was increased until the assembly 1 broke. In all cases, the powder-metallurgically manufactured components itself broke, not the connection area 4. In the course of this, forces of approximately 2,600 N were measured.

[0044] The exemplary embodiments show and/or describe possible embodiment variants, while it should be noted at this point that combinations of the individual embodiment variants are also possible.

[0045] Finally, as a matter of form, it should be noted that for ease of understanding of the structure, elements are partially not depicted to scale and/or are enlarged and/or are reduced in size.

LIST OF REFERENCE NUMBERS

[0046] 1 assembly

[0047] 2 component

[0048] 3 component

[0049] 4 connection area

[0050] 5 solder

[0051] 6 surface area

[0052] 7 pore

[0053] 8 line

[0054] 9 surface

[0055] 10 layer thickness