JPH028838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of joining a turbine wheel and a turbine shaft constituting a radial turbocharger or a small gas turbine, and an apparatus for carrying out the method, and particularly relates to a method of joining a turbine wheel and a turbine shaft that constitute a radial turbocharger or a small gas turbine, and an apparatus for implementing the method. The present invention relates to a method and apparatus for friction welding.

Turbine shaft assemblies, which make up radial turbochargers or small gas turbines used for energy recovery from engine exhaust gases, typically require an expensive Precision casting is performed using a heat-resistant alloy using the lost-work method, and the resulting cast product is polished in a subsequent process.The turbine shaft is also made of steel with good bearing characteristics, and is manufactured as described above. The turbine wheel and turbine shaft are integrally welded together.

By the way, as a method for joining the turbine wheel and the turbine shaft, since the materials of the turbine wheel and the turbine shaft are different as mentioned above, friction welding is often used, and the conventional method is the friction welding method. The specific method is as follows.

1 to 3 are for explaining an example of a conventional method of joining a turbine wheel 1 and a turbine shaft 2, in which the turbine wheel 1 is gripped by chucks 4 on the outer periphery of its blades 3, and , in order to bring the push rod 5 for receiving the thrust during joining into contact with the tip end surface 6 of the turbine wheel 1, and to prevent the turbine wheel 1 from rotating due to the rotational force received from the turbine shaft 2 during joining, the cross section has a rectangular shape. The plate 8 is fitted to the tip portion 7 formed so as to
is gripped by another chuck 9. In this state, at least one of the turbine wheel 1 and the turbine shaft 2 is rotated relative to the other together with the chucks 4 and 9 (in the case of rotating the turbine wheel 1, together with the chuck 4, the push rod 5, and the plate 8), Then, the tip of the turbine shaft 2 is pressed against the center of the back surface of the turbine wheel 1, thereby friction welding them together.

However, in the conventional method described above, since each of the chucks 4 and 9 is provided at the desired position,
If the turbine wheel 1 and the turbine shaft 2 are manufactured according to specifications, they will be positioned on the same axis by being gripped by the chucks 4 and 9. However, even if the turbine wheel 1 is precision cast, However, the roundness of the blade 3 may be slightly out of order due to deformation during casting or slight deviation of the casting mold based on the model made of wax, and the blade 3 may be slightly out of roundness. The center of the back surface, that is, the pressure contact surface 10 and the tip surface 6
If there is any deviation in perpendicularity to the central axis, the thrust during press-contact will act as a force to tilt the turbine wheel 1, which may cause the blades 3 to deform and the turbine wheel 1 to tilt. , Therefore, in the conventional joining method mentioned above,
There have been cases where the turbine wheel 1 and the turbine shaft 2 are joined with their central axes deviated from each other. Turbine shaft assemblies with misaligned coaxiality should be repaired after the joining work is completed.
As shown in FIG. 4, the back surface and center boss portion 1 of the turbine wheel 1 make it easy to locate the center of the turbine shape.
Center holes 12 and 13 are formed in the front end surface 6 of the turbine wheel 1 and the rear end surface of the turbine shaft 2 with reference to the outer peripheral surface of the turbine wheel 1.
If the turbine shaft assembly having the above configuration is attached to an appropriate cutting device via the
The coaxiality of the turbine shaft 2 and the turbine shaft 2 can be kept within the permissible value, and at the same time, the initial unbalance can be prevented since the back side and the center boss portion 11 of the turbine wheel 1 account for most of the total weight of the turbine wheel 1. It can be reduced to some extent. However, with the above-described joining method, the coaxiality of the resulting turbine shaft assembly may be relatively large, so it is necessary to provide sufficient machining allowance for the turbine shaft 2 in advance, and Cutting as a process takes time, and there are problems such as poor material yield due to the large amount of cutting chips that are removed.

In addition, in the conventional joining method described above, even if the coaxiality error that occurs during joining can be corrected by cutting in the subsequent process, a cavity is formed on the tip surface of the turbine shaft 2 to reduce heat transfer from the turbine wheel 1. If an air dam 14 (referred to as an air dam) is provided, the deviation of the air dam 14 from the axis of rotation remains, resulting in a very large initial unbalance of the turbine shaft assembly. Generally, such unbalance of the turbine shaft assembly is finally corrected by scraping off the vicinity of the tip 7 and the back side of the turbine wheel 1 according to the unbalance. As mentioned above, since the wheel 1 is made of a heat-resistant alloy, it is extremely difficult to cut it, and there is a large amount of cutting to be done, and in the end, the initial imbalance that occurred as described above cannot be completely corrected. The reality is that cases arise.

This invention has been made in view of the above circumstances, and provides a joining method and method that can improve coaxiality between a turbine wheel and a turbine shaft after joining and reduce initial unbalance as much as possible. The purpose is to provide a device for

That is, the method and device of the present invention, when positioning the turbine wheel at the desired position,
The turbine wheel is characterized in that positioning is performed with reference to the back side, which accounts for most of the total weight of the turbine wheel and is relatively easy to pull out at the center of the shape. To this end, in the present invention, a center hole is formed in the front end surface with reference to the back surface of the turbine wheel and the outer circumferential surface of the central boss portion, and the center hole is The turbine wheel was fixed to the support plate through the hole. In this way, by setting in advance the relative position of the pressing member for pressing through the support plate and the center hole with respect to the turbine shaft, the turbine wheel can be positioned coaxially with respect to the turbine shaft. It is possible to position and fix the turbine wheel, thereby improving the coaxiality between the turbine wheel and the turbine shaft after joining. Since the side or center boss is used as a reference, in other words, the center of rotation determined from the outer shape coincides with the center of weight as much as possible, so the initial unbalance of the resulting turbine shaft assembly can be significantly reduced. .

Embodiments of the present invention will be described below with reference to FIGS. 5 to 7. First, an embodiment of the welding apparatus of the present invention will be described. FIG. 5 shows a cross-sectional plan view of the welding apparatus according to the present invention, and FIG. 6 shows a longitudinal cross-sectional side view thereof, in which the turbine wheel 1 is A base 20 for fixing the turbine shaft 2 and a chuck 21 for gripping and rotating the turbine shaft 2 are arranged to face each other, and the base 20 has a housing section 22 for housing the turbine wheel 1 on the chuck 21. It is formed with an opening on the side. A through hole 23 is formed in the center of the wall of the accommodating portion 22 facing the chuck 21 so that its central axis coincides with the turbine shaft 2 held by the chuck 21. The tip of a piston rod 25 of the hydraulic cylinder 24 is fixed to the open end on the back side (the right side in FIGS. 5 and 6). Further, a center pin 26 is inserted into the through hole 23 so as to be movable back and forth so that its center axis coincides with the turbine shaft 2 held by the chuck 21, and between the center pin 26 and the tip end surface of the piston rod 25. A spring 27 is arranged at. The tip of the center pin 26 protrudes toward the accommodating portion 22 side, and a sphere 28 is attached to the tip. The turbine wheel 1 is pressed against the turbine wheel 1 while being inserted into the central hole 29 .

A receiving seat plate 30 and a torque plate 31 serving as a rotation stopper are sequentially laminated on a wall surface of the accommodating portion 22 facing the chuck 21, and are fixed to the base 20 with bolts 32.
The catch plate 30 has a hole through which the protruding end of the center pin 26 passes, and a spherical catch 33 formed on the contact surface with the torque plate 31. Bearing member 34
is arranged, and by bringing the tip end surface 6 of the turbine wheel 1 into surface contact with the bearing member 34, the thrust force applied to the turbine wheel 1 during joining is received by the base 20 via the bearing member 34 and the receiving seat plate 30. It's getting old. Note that the bearing member 3
4 is formed with a through hole having a larger diameter than the projecting end in order to allow the projecting end of the center pin 26 to pass therethrough. Therefore, the front bearing member 34 can be moved to a certain extent without interfering with the center pin 26. It is designed to be able to rotate within a range of . Further, the torque plate 31 is formed with a recessed portion in the central portion on the rear side, that is, on the receiving seat plate 30 side, to allow rotation of the bearing member 34, and as shown in FIG. A rectangular hole 35 into which the tip 7 of the turbine wheel 1 is fitted is formed in the center, and by fitting the tip 7 of the turbine wheel 1 into the rectangular hole 35, the rotation of the turbine wheel 1 is controlled. It is designed to prevent it.

Furthermore, a support plate 36 is disposed between the base 20 and the chuck 21 so as to be perpendicular to the central axes of the turbine shaft 2 held by the chuck 21 and the center pin 26. This support plate 36 fixes the turbine wheel 1 between it and the center pin 26 in a state where the back surface of the turbine wheel 1 (more precisely, the back surface of the center boss portion 11) is in contact with the support plate 36. This support plate 3
6 is connected to the flange plate 38 of the hydraulic cylinder 24 by a plurality of rods 37 provided through the base 20, and therefore the support plate 36
is adapted to move toward and away from the base 20 by operating a hydraulic cylinder 24. Note that an insertion hole 39 is formed in the support plate 36 to allow the turbine shaft 2 to come into contact with the pressure contact surface 10 of the turbine wheel 1 .

Next, the operation of the bonding apparatus configured as described above, that is, the bonding method of the present invention will be explained.

First, a center hole 29 is formed in the distal end surface 6 of the turbine wheel 1, which has been precision cast and polished, with reference to the back surface of the turbine wheel 1 and the outer peripheral surface of the central boss portion 11. On the other hand, by operating the hydraulic cylinder 24 and bringing it closer to the base 20, the support plate 36 connected to the hydraulic cylinder 24 by the rod 37 is separated from the base 20 to some extent. put. Then, the turbine wheel 1 is inserted into the accommodating portion 22, and the ball 28 attached to the tip of the center pin 26 is inserted into the center hole 29 formed in the tip surface 6, and the tip 7 of the turbine wheel 1 is applied with torque. Square hole 3 of plate 31
Then, by operating the hydraulic cylinder 24 in the opposite direction to the above case, the support plate 36 is brought closer to the base 20, the back surface of the turbine wheel 1 is brought into contact with the support plate 36, and the turbine wheel 1 is then inserted into the support plate 36. The turbine wheel 1 is pressed until the front end surface 6 of the wheel 1 comes into contact with the bearing member 34 . In this way, the center pin 26 and piston rod 25
Since the spring 27 disposed between the center pin 26 and the front end surface of the turbine wheel 1 is compressed, the turbine wheel 1 is held and fixed between the center pin 26 and the support plate 36 by the elastic force of the spring 27. In this case, the center hole 29 is formed based on the back surface of the turbine wheel 1 and the outer circumferential surface of the center boss portion 11, and the back surface of the turbine wheel 1 is in contact with the support plate 36 through the center hole 29. Since the back side and center boss portion 11 of the turbine wheel 1 account for the majority of the total weight of the turbine wheel 1, the turbine wheel 1 substantially has its center of weight attached to the turbine shaft. It is positioned so that it is aligned with the central axis of No. 2.

Position the turbine wheel 1 as described above.
After fixing, tighten the turbine shaft 2 with the chuck 21.
The turbine shaft 2 is frictionally welded to the turbine wheel 1 by pressing its tip against the pressure contact surface 10 of the turbine wheel 1 while rotating the turbine shaft 2 at the same time. In this case, the thrust force applied to the turbine wheel 1 is received by the receiving seat plate 30 via the hemispherical bearing member 34, but the bearing member 34 contacts the spherical receiving seat 33 and is rotatable. Therefore, even if the tip surface 6 of the turbine wheel 1 is not exactly perpendicular to the central axis but is slightly inclined, the bearing member 34 will rotate in response to the inclination of the tip surface 6 of the turbine wheel 1. As a result, no force is generated that acts to tilt the turbine wheel 1, and thus, together with the fact that the turbine wheel 1 and the turbine shaft 2 are positioned with their respective central axes coincident,
Both are accurately joined without causing so-called misalignment. It goes without saying that the turbine wheel 1 is prevented from rotating during friction welding by the torque plate 31 to which the tip end 7 of the turbine wheel 1 is fitted.

After joining the turbine wheel 1 and the turbine shaft 2 as described above, if the hydraulic cylinder 24 is operated to bring the hydraulic cylinder 24 and the base 20 relatively close together, the supporting plate 36 is separated from the base 20, the clamping and fixation of the turbine wheel 1 is released, and the turbine wheel 1 and the turbine shaft 2, that is, the turbine shaft assembly can be removed from the joining device.

The turbine shaft assembly obtained in this way has almost no deviation in coaxiality between the turbine wheel 1 and the turbine shaft 2, and furthermore, the turbine wheel 1 is connected to the back surface and the center boss portion 1 of the turbine wheel 1.
1 as a reference, in other words, the turbine wheel 1 is positioned substantially with the center of gravity as a reference, so that the initial unbalance is extremely small.

In the device of the above embodiment, the spherical catch 33 is formed on the catch plate 30, and the catch plate 30 is fixed to the base 20, but instead of this, the spherical catch 33 is attached to the base 20. Alternatively, instead of attaching the sphere 28 to the tip of the center pin 26, the tip of the center pin 26 may be made spherical. Further, in this invention, when positioning and fixing the turbine wheel 1 with respect to the turbine shaft 2, instead of bringing the back surface of the turbine wheel 1 into contact with the support plate, the outer periphery on the back side of the central boss portion 11 of the turbine wheel 1 The turbine wheel 1 may be held by a suitable support plate and simultaneously pressed by a center pin 26 fitted into the center hole 29. Even in this method, the center of gravity of the turbine wheel 1 can be centered around the rotation center as in the embodiment described above. They can be positioned and fixed in a matched state.

As is clear from the above description, according to the joining method of the present invention, when joining the turbine shaft to the center of the back surface of the turbine wheel by friction welding, the front end surface of the turbine wheel is connected to the back surface and the outer circumferential surface of the center boss part as a reference. The turbine wheel is fixed by forming a center hole and pressing the turbine wheel against the support plate through the center hole with the back surface of the turbine wheel in contact with the support plate. , since the rear side and central boss portion of the turbine wheel account for most of the total weight, the turbine wheel can be positioned so that its center of weight substantially coincides with the central axis of the turbine shaft, and therefore the turbine wheel and the turbine shaft It is possible to improve the coaxiality with the turbine shaft assembly, and at the same time, it is possible to reduce the initial unbalance of the resulting turbine shaft assembly. Further, according to the welding device of the present invention, the welding device is arranged coaxially with the turbine shaft so as to press the turbine wheel through the center hole formed in the front end surface of the turbine wheel with reference to the back surface of the turbine wheel and the outer peripheral surface of the center boss portion. Since the turbine wheel is provided with a center pin and a support plate that makes contact with the back surface of the turbine wheel, and the turbine wheel is held and fixed between the center pin and the support plate, the center of weight of the turbine wheel is substantially aligned with the center axis of the turbine shaft. a hemispherical bearing member that is in surface contact with the tip surface of the turbine wheel;
Since a spherical seat that rotatably supports the bearing member is provided, even if the tip surface of the turbine wheel is not perpendicular to the center axis but is slightly inclined, the thrust during friction welding will The turbine wheel does not tilt, so the turbine wheel and turbine shaft can be joined while maintaining the coaxiality that was set at the beginning of joining, and the initial unbalance of the resulting turbine shaft assembly is reduced. can be reduced to an unprecedented degree. Further, according to the joining method and apparatus of the present invention, it is possible to reduce the initial unbalance of the turbine shaft assembly obtained by joining the turbine wheel and the turbine shaft, so that correction work in the subsequent process can be reduced. It is extremely simple, and has secondary effects such as reducing machining allowance provided in advance on the turbine shaft and making it possible to reduce the diameter of the turbine shaft material.

[Brief explanation of drawings]

Figures 1 to 3 are for explaining the conventional joining method, in which Figure 1 is a sectional view showing a state in which the turbine wheel and the turbine shaft are each gripped by a chuck, and Figure 2 is a sectional view showing the gripping FIG. 3 is a front view of the turbine wheel to show locations, FIG. 3 is a top view of the same, FIG. 4 is a cross-sectional view showing a method for centering the turbine shaft assembly, and FIG. 5 is an embodiment of the joining device of the present invention. 6 is a longitudinal sectional view of the same, and FIG. 7 is a front view showing the torque plate. DESCRIPTION OF SYMBOLS 1... Turbine wheel, 2... Turbine shaft, 6... (Turbine wheel) tip surface, 7...
Tip part (of the turbine wheel), 10... Pressure contact surface (of the turbine wheel), 11... Center boss part, 26
... Center pin, 29 ... Center hole, 31 ... Torque plate, 33 ... Spherical bearing seat, 34 ... Hemispherical bearing member, 36 ... Support plate.

Claims (1)

[Claims] 1. When friction welding the turbine shaft to the center of the back surface of the turbine wheel, a center hole is formed in the tip surface of the turbine wheel with reference to the back surface of the center boss portion of the turbine wheel and the outer peripheral surface of the center boss portion. The turbine wheel is pressed toward the support plate through the center hole while the back surface of the center boss portion is brought into contact with the support plate, or the outer periphery of the back surface of the center boss portion is gripped by the support plate. By doing so, the turbine wheel is positioned and fixed coaxially with respect to the turbine shaft, and in this state, at least one of the turbine wheel and the turbine shaft is rotated and the two are brought into pressurized contact to be joined. A method for joining a turbine wheel and a turbine shaft. 2. A welding device in which a turbine wheel and a turbine shaft are positioned coaxially and at least one of the turbine wheel and the turbine shaft is rotated to frictionally weld the turbine shaft to the center of the back surface of the turbine wheel. A support plate that supports the turbine wheel with its back surface or the outer circumference of the back surface in contact and has a turbine shaft insertion hole; a center pin disposed coaxially with the turbine shaft so as to fix the turbine wheel to the support plate through a center hole; and a hemispherical bearing member disposed so as to be in surface contact with a tip end surface of the turbine wheel. , comprising a spherical seat that rotatably supports the hemispherical bearing member, and a rotation stopping member that prevents rotation of the turbine wheel fixed between the support plate and the center pin. A device for joining the turbine wheel and turbine shaft.