Metal fusion bonding – Process – Using dynamic frictional energy
Reexamination Certificate
1998-10-06
2001-03-13
Heinrich, Samuel M. (Department: 1725)
Metal fusion bonding
Process
Using dynamic frictional energy
C228S219000, C228S002100, C228S042000, C239S290000, C239S590000
Reexamination Certificate
active
06199744
ABSTRACT:
The invention relates to a friction welding process according to the preamble of patent claim
1
, as well as a shielding gas shower for carrying out the process according to claim
6
. Such a friction welding process is disclosed in EP 513,669 B1.
Such friction welding processes serve for mounting the blades of a blade carrier of a flow machine, for example of entire disks (blisk) or a drum for a jet engine. The blade carrier comprises a conical or cylindrical contour, on the circumference of which a plurality of uniformly mutually spaced blades are welded by means of their blade roots. Both the circumference of the blade carrier as well as the blade root comprise a plane or slightly curved welding surface, and are pressed together by means of an upsetting compressing force in order to develop the necessary welding temperature, so that the area of the welding surfaces is heated to the welding temperature during the translational pendular motion of the blades relative to the blade carrier. The pendular motion is carried out perpendicularly to the longitudinally extending configured welding surface, and can amount to several millimeters in this context.
The friction welding process, which belongs to the class of pressure welding or plastic welding processes, distinguishes itself relative to typical gas or arc melt welding processes by a substantial insensitivity with respect to oxidation in the surrounding ambient air, because, due to the relative motion of the parts to be welded, firstly the access of surrounding ambient air is hindered, and secondly oxides are transported together with the molten material out of the weld zone due to the rubbing frictional motion. Nonetheless, defects have been discovered in the edge and corner areas in the weld seam due to oxide formation. Since such defects reduce the strength of the weld seam, the danger of a blade rupture exists during operation of the flow machine due to the high centrifugal forces.
Beginning from this background, it is an object of the invention to provide a friction welding process of the general type described above for mounting the blades of a blade carrier, which ensures a defect-free welded junction between the blade carrier and the blades. Moreover, a shielding gas shower of the general type described above is to be provided such that it can be employed for carrying out a friction welding process without hindering the relative motion between the bodies that are to be joined.
With regard to the process, the object is achieved according to the invention by means of the characterizing features of patent claim
1
.
In contrast to the known rotational friction welding processes, in the welding process of the general type described above using an oscillating relative motion, it cannot be avoided that areas of the welding surfaces corresponding to the amplitude of the relative motion are exposed, and the exposed welding surface is subjected to oxidation due to access by air. In this context, the invention has the advantage that, due to the flowing of a shielding gas around the welding surfaces, these surfaces are surrounded by a shielding gas curtain, so that these are protected against access by air during their relative motion. Due to the fact that the blade and blade carrier form a flow grating, the surrounding flow of the shielding gas effectuates a similar flow field or pattern as occurs during operation of the blade carrier. In other words, the shielding gas flow follows the contour of the blade carrier and of the blade and thus serves to provide a closed shielding gas curtain for protecting the welding surface. Thus, no further measures are needed for maintaining the flow in the area of the welding surfaces, even during the relative motion of the bodies.
In this context it is advantageous to orient the welding surfaces, which are provided with an over-dimension relative to the finished part contours, at the blade angle &bgr; and taper angle &agr;, so that the shielding gas flow that develops has a flow that lies against the hub area of the flow machine for as long as possible, similarly as in the case of operating the flow machine, whereby the welding surfaces remain covered by shielding gas. This effect is further reinforced in that the shielding gas flow encompasses at least that area passed over by the moving welding surface, which is made possible by corresponding expansion of the shielding gas flow in the direction of the pendular motion. By correspondingly orienting the shielding gas flow with respect to the taper angle &agr; of the blade carrier and the angle of incidence &bgr; of the welding surfaces, a largely adherent or contacting shielding gas flow is achieved in the area of the welding surfaces. In order to ensure a shielding gas supply with the minimum possible interference on the one hand, and the operation of the friction welding process without interference on the other hand, the direction of the shielding gas flow is oriented transverse or perpendicularly to the direction of the relative motion, whereby the relative motion carries out an essentially translational or slightly arc-shaped motion.
The object of the invention relating to the shielding gas shower is achieved according to the invention by means of the characterizing features of patent claim
6
.
In order to achieve a supply of gas to the welding surfaces from all sides to the extent possible during the relative motion, the shielding gas shower, which is stationary relative to one of the bodies, comprises a gas outlet opening facing the welding surfaces. The expansion of the gas outlet opening in the motion direction has the advantage for the invention that the area passed over by the moving welding surface is gasable, i.e. can have gas supplied thereto, without gaps, and thus air access to the oxidation sensitive welding surfaces can be prevented. By means of the stationary construction of the shielding gas shower, firstly a defined area passed over by the shielding gas is achieved, and secondly the supply of the shielding gas to the shielding gas shower is simplified.
The arrangement of the shielding gas shower with a spacing perpendicular to the motion direction allows the friction welding process to be carried out unhindered, so that the geometrical motion sequences generally can be maintained. Also thereby, it becomes possible to achieve a gas showering of the welding surfaces that comes close to the actual flow conditions, so that the above initially mentioned advantages with regard to the flow guidance can optimally be ensured, especially since this makes it possible to achieve the gas outlet that is optimal for the flow guidance transversely or perpendicularly to the motion direction.
In an advantageous manner, the shielding gas shower is embodied corresponding to the contour of one of the bodies in the area of the welding surface. Generally, the shielding gas shower is mounted on the blade carrier that is stationary during the friction welding process, so that the shielding gas shower is embodied with an arc-shape corresponding to the cylindrical contour of the blade carrier. Thereby, the shielding gas shower can be mounted surfacially on the disk carrier, so that the access of air between the disk carrier and the shielding gas shower, and therewith an all too intensive mixing with the shielding gas in the area of the welding surfaces, can be prevented.
Further advantageous embodiments of the invention with regard to uniform distribution of the shielding gas over the outlet opening, are achieved by the features of patent claims
11
to
13
.
REFERENCES:
patent: 3597833 (1971-08-01), Frederick et al.
patent: 3875364 (1975-04-01), Boyett
patent: 4871894 (1989-10-01), Suzuki et al.
patent: 5314106 (1994-05-01), Ambroziak et al.
patent: 5388753 (1995-02-01), Bjorkman, Jr.
patent: 5393948 (1995-02-01), Bjorkman, Jr.
patent: 5981897 (1999-11-01), Offer et al.
patent: 3401078C1 (1984-01-01), None
patent: 0513669A2 (1992-05-01), None
patent: 0513669 (1992-11-01), None
patent: 361092796A (1986-05-01), None
patent: 405131280A (1993-05-0
Katheder Karl
Muschal Georg
Schneefeld Dieter
Thaler Erich
Fasse W. F.
Fasse W. G.
Heinrich Samuel M.
MTU Motoren - und Turbinen-Union Muenchen GmbH
LandOfFree
Friction welding process and shielding gas shower for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Friction welding process and shielding gas shower for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Friction welding process and shielding gas shower for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2456098