The invention relates to a method for producing an impulse mistuning component, according to the preamble of claim 1.
Such an impulse mistuning component is disclosed for example in the application DE 10 2014 223231 (not yet published at the time of filing the present application). The impulse mistuning component here is illustrated in a perspective manner in
In another embodiment which is depicted on the left side of
The present invention is thus based on the object of proposing a method for producing an impulse mistuning component such that hardly any or no fissures arise in the mistuning component under operating conditions.
The object is achieved by the features of claim 1.
The invention relates to a method for producing an impulse mistuning component for a turbine. The method comprises substantially the steps that are listed hereunder. in step a) a container having at least one chamber is produced. in step b) a lid is produced. Subsequently, in step c), an impulse element is inserted into the chamber. In step d) the lid and the container are then joined, wherein joining is carried out by soldering/brazing.
The impulse element herein can be a simple ball. Cylindrical elements are also conceivable. The shape depends on the shape of the chamber or pocket, respectively, in which the impulse element is later placed. It is only important for the chamber to be larger than the impulse element such that the latter has sufficient space for moving back and forth in the chamber.
It is advantageous herein that notches do not arise in the joining zone. The service life of the mistuning component is thus significantly increased. It is to be noted the container can have more than one mutually separated chambers. These chambers can then be disposed in the form of an egg box.
In one advantageous design embodiment of the invention, a furnace, an inductive coil, a laser beam, and/or an electron beam are/is used as a heat source for soldering/brazing. The heat treatment can furthermore be carried out in a vacuum and/or in a protective atmosphere. The vacuum can have a residual pressure of 10−5 mbar to 10−3 mbar.
In one further advantageous design embodiment of the invention, the sequence of steps a) and b) is arbitrary. Step c) herein follows step a), and step d) herein follows steps b) and c).
In one further advantageous design embodiment of the invention, the production of the lid in step b) is carried out by punching, by laser beam welding, and/or by spark erosion. In the production by means of spark erosion (EDM=electrical discharge machining), an oxide layer in the form of a recast layer is created on the surface of the lid. Such an oxide layer has the advantage that it acts in a wetting-inhibiting manner. It can thus be prevented in a targeted manner that solder reaches undesirable locations. Those locations to which the solder is to be applied have to be relieved of the oxide layer. In general, lids can be produced in an extremely cost-effective manner by punching.
In one further advantageous design embodiment of the invention, the production of the container in step a) is carried out by spark erosion, electrochemical processing, and/or mechanical subtraction, in particular by milling and/or grinding. In the production by means of spark erosion (EDM=electrical discharge machining), an oxide layer in the form of a recast layer is created on all surfaces of the container, and thus also on the walls that enclose the chamber. It is thus advantageously prevented that solder ingresses into the chamber and disturbs or impedes, respectively, the mobility of the impulse element. Those locations to which the solder is to be applied have to be relieved of the oxide layer. A nickel alloy such as, for example, Haynes 230 is preferably used for the container.
In one further advantageous design embodiment of the invention, after step a) and before step c) the internal wall of the chamber is irradiated with Al2O3. In particular, when the container has been produced by means of mechanical subtraction or electrochemical processing (ECM=electrochemical machining). The periphery of the container herein can either be covered, or the surface of the irradiated periphery is subtracted.
In one further advantageous design embodiment of the invention, before step d) at least one encircling part of the container to which the solder is applied before step d) is relieved of oxide. This has the advantage that a high-grade soldered/brazed connection can be created.
In one further advantageous design embodiment of the invention, the soldering/brazing time in step d) is 1 s to 60 s.
In one further advantageous design embodiment of the invention, a preshaped filler is placed on the container and/or on the lid before step d), The preshaped filler can be cut out, for example by laser beam cutting, so as to correspond to the contour of the container. A nickel-based solder such as AMS4777 is suitable as a solder material. The thickness of the preshaped filler can be 25 μm to 50 μm.
In one further advantageous design embodiment of the invention, the preshaped filler is adhesively bonded to both sides on the lid and on the container before step d). As a result, the two parts are fixed to one another. A respective adhesive can evaporate without residue in step d). This has the advantage that handling is significantly simplified. Alternatively, the completed component (container, lid, and preshaped filler) can be fixed by means of tack welding. One tacking point per side can be provided herein.
In one further advantageous design embodiment of the invention, the external width bbA of the container and the external width fbA of the preshaped filler meet the condition bbA≧fbA. Furthermore, the internal width bbI of the container and the internal width fbI of the preshaped filler meet the condition bbI≦fbI, where fbA>fbI. Furthermore, the external length bLA of the container and the external length fLA of the preshaped filler can meet the condition bLA≧fLA, and the internal length bLI of the container and the internal length fLI of the preshaped filler can meet the condition bLI≦fLI, where fLA>fLI. In one particular embodiment, the preshaped filler goes up to the periphery of the container. Here: bbA=fbA and bLA=fLA. This has the advantage that encircling soldering/brazing can be performed, such that the chamber is dosed off from the external environment in a gas-tight manner. In order for the lid to terminate so as to be flush with the container, the dimensions of the lid have only to meet the following conditions: dbA≧bbA and dLA≧bLA, where dbA is the lid width, and dLA is the lid length. Should the lid have the same external dimensions as the container, the lid in step d) is to be aligned so as to be flush with the container. However, the lid can be somewhat repositioned during soldering/brazing. This can be avoided by suitable fixing.
Alternatively thereto, the lid can be larger than the container in all directions. To this end, after step d) that part of the lid that protrudes beyond the periphery of the container should be mechanically subtracted until the lid is flush with the periphery.
Further advantageous design embodiments of the invention are reflected in the dependent claims.
Preferred exemplary embodiments of the invention will furthermore be described in more detail by means of the schematic drawing in which:
A cross section through a mistuning component 30, 30′ having a lid 32, 32′ and a box-shaped container 34 is depicted in
A plan view of the preshaped filler 46 to be used is in
In the first embodiment (see
A second embodiment of a mistuning component 30′ produced according to the invention is in
The method according to the invention will now be described hereunder. In steps a) and b) the lids 32′ are punched preferably from metal, and the egg-box-shaped container 34 is produced. At least one ball (impulse element) is inserted into each chamber 36. Subsequently, the sticky lower side of the preshaped filler 46′ is adhesively bonded to the external walls 42 and 44 of the container 34. The lid 32′ is adhesively bonded to the sticky upper side of the preshaped filler 46′. Attention has to be paid herein that all three parts (preshaped filler, lid, container) are mutually aligned so as to be flush. The preshaped filler 46′ is subsequently made to melt.
Number | Date | Country | Kind |
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16160546.4 | Mar 2016 | EP | regional |