RU2766654C1 - Method for manufacturing a bimetallic turbine impeller - Google Patents

Abstract

FIELD: engine technology.

SUBSTANCE: invention relates to the field of engine building, to axial turbines of gas turbine engines, in particular to a method for manufacturing bimetallic turbines impellers of gas turbine engine turbines made in the form of a blisk. A method for manufacturing a bimetallic turbine impeller in which blades made of one alloy are connected to a disk blank made of another alloy into a single part by hot isostatic pressing, cavities and vents are performed in the disk blank, powder is poured into the cavities for diffusion welding, the powder is compacted by pressing, then the blade roots are inserted into the cavity with the powder, forming a connection with a fixed seating of the blades in the cavities of the disk blank, before diffusion welding, air is pumped out of the cavities through the exhaust vents and the exhaust vents are muffled, then diffusion welding is performed with hot isostatic pressing of the blades with the disk blank, after diffusion welding, final processing is performed, during which ledges are removed and smooth transitions are formed on the surface from the blade roots to the disk part.

EFFECT: invention makes it possible to ensure the efficiency and reliability of the technology, as well as simplify the manufacturing process of bimetallic turbine impellers.

1 cl, 3 dwg

Description

The invention relates to the field of engine building, to axial turbines of gas turbine engines, in particular to a method for manufacturing bimetallic impellers of turbines of gas turbine engines, made according to the blisk type.

The prior art method of manufacturing bimetallic impellers according to patent RU 2467177, selected as the closest analogue. In this method, individual blades made of one metal alloy are connected to a disk part made of another metal alloy, the blades are connected to the disk part into a single part by hot isostatic pressing (HIP) in a zone approximately equal to the long-term strength of these alloys, while the profile part , the tract shelf and part of the leg above the specified zone of any of the blades are located outside the HIP impact zone, and the other part of the leg and the disk part are encapsulated and placed in the impact zone, the blade legs are aligned with the disk, mainly end-to-end, and the area of the zone is approximately equal to the long-term strength of both alloys determined previously, for example, according to the long-term strength curves of Larson-Miller.

In the manufacture of bimetallic impellers using hot isostatic pressing (HIP), an intermediate operation is used to solder the blades into a technological ring and a capsule is made to hold the blades and ensure tightness during HIP.

The disadvantage of this method is the use of the process of soldering the blades into the technological ring and the manufacture of the capsule. The soldering process requires the manufacture of massive technological parts of the capsule (rings and covers) with the exact dimensions of the gaps for soldering the blades. Operations of selection of blades to ensure accurate gaps, installation of blades in the ring, assembly and removal of the capsule and subsequent removal of the technological ring are laborious, they increase the cost of technology. In addition, there are risks of defective solder joints and uneven bulk density of the powder in the capsule, since it is impossible to control the quality of the solder joints and the uniformity of the bulk density of the powder using non-destructive control methods.

The purpose of the invention is to ensure the efficiency and reliability of the technology, as well as to simplify the process of manufacturing bimetallic turbine impellers.

This goal is achieved by the fact that in the proposed method for manufacturing a bimetallic turbine impeller, blades made of one alloy are connected to a disc blank made of another alloy into a single part by hot isostatic pressing, cavities and gas outlet holes are made in the disc blank, and filled for diffusion welding. powder in the cavity, the powder is compacted by pressing, then the legs of the blades are inserted into the cavities with the powder, forming a connection with a fixed fit of the blades in the cavities of the disc blank, before diffusion welding, air is pumped out of the cavities through the gas outlet holes and the gas outlet holes are muffled, then diffusion welding is performed at hot isostatic pressing the blades with the disk blank, after diffusion welding, final processing is carried out, during which ledges are removed and smooth transitions are formed on the surface from the blade roots to the disk part.

Fig. 1 is a cross-sectional view of the disk blank at the place of landing of the blade with a gas outlet from a flat side surface.

Fig. 2 is a cross-sectional view of the disk blank at the place of landing of the blade with a gas outlet from the cylindrical rim surface.

Fig. 3 - shows a three-dimensional model of a bimetallic turbine impeller after machining, indicating a smooth transition (fillet).

1 - annular disk blank

2 - cavities

3 - leg (shank) of the blade

4 - powder

5 - gas outlets

6 - fillet.

In the annular disc blank 1 shown in FIG. 1 and 2, cavities 2 are made according to the dimensions of the legs of the blades 3. Powder 4 is poured into the cavity from a heat-resistant granular nickel alloy for diffusion welding during HIP. The powder is compacted by pressing. Then, the blade roots are inserted into the cavities with the powder, forming a connection with a fixed fit of the blades (interference fit) in the cavities of the disc blank. It is allowed to press the powder with the help of the legs of the blades. The ends of the blade legs prevent the powder from pouring out when the disk blank is turned. In the disk blank, gas outlet holes 5 are provided for pumping air out of the cavities with powder. The vent holes 5 can be made both before the powder is pressed in, and after the powder is pressed in, or after the blades are pressed in. The vent holes can be located both on the flat side surface of the disc blank and on the cylindrical rim surface of the disc blank, at an angle to the blade axis, as shown in FIG. 2

The blades in the disc blank are held by a fixed fit. Before diffusion welding, air is pumped out of the cavities through the gas outlet holes, after which the gas outlet holes 5 are silenced. Then, the operation of diffusion welding in the process of hot isostatic pressing (HIP) of the blades with the disc blank is performed at a pressure of 150 ... 200 MPa, and at a temperature above 1250 degrees. After diffusion welding, the final processing of the bimetallic turbine impeller is carried out, during which ledges are removed and smooth transitions (fillets) 6 are formed on the surface from the blade roots to the disk part, as shown in Fig. 3.

The shape of the blade root and the cavity in the disc blank must ensure the tightness of the joint. It has been established that the best option for the cross-sectional shape of the blade root and the cavity in the disc blank is a circle, since such a shape can be made with high accuracy, high repeatability, with minimal manufacturing costs, and is the simplest form for calculating a fixed fit.

Unlike the prototype, where during diffusion welding of the blades soldered into the technological ring with the disc blank, where the powder is located in the entire annular gap between the blades and the disc blank, in the proposed technology, the powder is poured into cavities, the cross-sectional area of which is approximately equal to the cross-sectional area of the ends of the legs shoulder blades. This achieves maximum savings in powder for diffusion welding.

The invention is intended to be used in the field of aircraft engine building.

Claims (1)

A method for manufacturing a bimetallic turbine impeller includes: blades made of one alloy are connected to a disk blank made of another alloy into a single part by hot isostatic pressing, characterized in that cavities and gas outlet holes are made in the disk blank, powder is poured for diffusion welding in the cavity, the powder is compacted by pressing, then the legs of the blades are inserted into the cavities with the powder, forming a connection with a fixed fit of the blades in the cavities of the disc blank, before diffusion welding, air is pumped out of the cavities through the gas outlet holes and the gas outlet holes are muffled, then diffusion welding is performed during hot isostatic pressing blades with a disk blank, after diffusion welding, final processing is carried out, during which ledges are removed and smooth transitions are formed on the surface from the blade roots to the disk part.

Images