JPS59185541A - Coupling method of shaft and shaft - Google Patents

Abstract

PURPOSE:To couple securely two shafts with good accuracy in such a way as to withstand the torque in the axial and rotating directions of both shaft in the stage of coupling the two shafts by working a stopper groove on the outside circumference of the one shaft, fitting the other shaft thereto and ironing the outside circumference thereof. CONSTITUTION:A turbine revolving shaft 2 is projected from a turbine vane wheel 3 formed of ceramics or a casting in such a case in which the revolving shaft of a supercharger of an internal combustion engine, etc. is coupled to the shaft of the vane wheel. A coupling shaft 5 having the diameter smaller than the diameter of the shaft 2 is provided and plural pieces of rugged stopper grooves 5A extending in the axial direction are preliminarily formed on the shaft 5. After the circumference of the wheel 3 is held by a die 7, the shaft 2 is fitted to the shaft 5 and a die 6 is suspended from above to iron the shaft. The assembly is then disposed on a receiving die 8 so as to position downward the wheel 3 and the shaft 2 is plastically deformed by the outside ironing with the die 9, by which a compressor vane wheel 4 is bound thereto.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a shaft-to-shaft coupling method, and in particular to a shaft-to-shaft method suitable for coupling a rotating shaft and an impeller shaft of a supercharger for an internal combustion engine, etc. Regarding the method of joining.

[Background of the invention]

In general, there are two ways to connect shafts: one is to arrange the shafts in series and connect them, and the other is to connect a hollow shaft to the shaft.

JP-A-57-122125 discloses a method of connecting shafts to each other in a supercharger for an internal combustion engine. For example, in the case of a turbocharger, a turbine impeller (cast product) that is exposed to high temperatures is fixed to one side of the rotating shaft by friction welding, and an aluminum H compressor impeller rotates to the other side. After being fitted onto the shaft, it is tightened and fixed with a nut.

In this manner, one impeller is fixed to the turbine rotating shaft of the supercharger by welding, and the other impeller is fixed by screws, in consideration of strength and assembly. However, fixing by welding has poor workability and has a large thermal effect on the impeller since it is heated and fixed, and workability is extremely poor for products that require precision on the micron level. On the other hand, according to the nut tightening method using screws, tension is always applied to the rotating shaft by the nut, so even if a small bending force is applied to the rotating torque, the rotating shaft can easily bend, which can be a problem. Ta. Not only is this bend unable to maintain a very small gap with the compressor casing, but objects may come into contact with the casing, resulting in the loss of the product's life. Furthermore, in order to reduce the bending of the rotating shaft, it is necessary to improve the machining accuracy of the nut. In other words, in mass-produced products, it is said to be extremely difficult to ensure the thread accuracy of nuts, the perpendicularity between the screw and the tightening end face, and the core accuracy of the screw center and outer diameter in microscopic units. If that happens, it is inevitable that Natsuto's cost will increase.

Furthermore, the maximum rotational speed of an exhaust turbine supercharger varies depending on the size, but it is an extremely high-speed rotating machine of 1000 to 280,000 (rpm), and the balance of the rotating body is vital.

This balance accuracy requires several microns, and it is necessary to improve the balance accuracy of each component, and it is also necessary to ensure the balance accuracy of the assembled state of the rotating body, not just the balance of individual parts. However, the above-described through welding and nut fastening methods impair balance accuracy and at the same time cannot ensure balance accuracy of several microns during assembly.

[Purpose of the invention]

The present invention provides a shaft-to-shaft coupling method with high coupling precision and product precision.

[Summary of the invention]

In the present invention, a groove for preventing rotation is machined on the outer periphery of the shaft, another shaft is fitted into the shaft, and the outer periphery is squeezed so that the two shafts can withstand torque in the axial and rotational directions. It is a strong fixed bond.

[Embodiments of the invention]

FIG. 1 shows an installed state diagram of an exhaust turbine supercharger embodying the present invention. A turbine rotary shaft 2 is supported in the center of the housing case 1 via a bearing, a turbine impeller is fixed to one side of the shaft, and a compressor impeller is fixed to the other side.

The turbine impeller 3 is made of a cast product or a ceramic material.As shown in detail in FIG. 2, the turbine impeller 3 protrudes from the center of the impeller in advance and has a diameter smaller than that of the first member, the turbine rotating shaft 2. A shaft 5 is provided, and a plurality of projections and depressions 5A extending in the axial direction are formed on the joint shaft 5 by knurling.

The length of this unevenness 5A is appropriate, but both ends 5B, 5
As can be seen from FIG. 4, the diameter D6 of C is at least smaller than the outer diameter D5 of the unevenness. On the other hand, the outer diameter D of the coupling shaft 5
A recessed hole 2A is formed at the end of the turbine rotating shaft 2, which is the second member to be fitted with the second member, and the recessed hole 2A is smaller than the hole diameter D5 and is freely fitted. An annular protrusion 2B is formed on the outer diameter part of the recessed hole 2A, the outer diameter D3 of both ends of which is approximately equal to the inner diameter D1 of the machining tooth 6A of the mold 6, which is formed separately, and the outer diameter D2 It is designed so that it does not come into contact with anything other than the machined teeth 6A of No. 6.

Therefore, after holding the circumference of the turbine impeller 3 vertically with the mold 7, the turbine rotating shaft 2 is fitted and held on the coupling shaft 5,
Further, the mold 6 is lowered from above and the protrusions 2B are pressed against the processing teeth 6A to perform processing.

Then, the inside of the protrusion 2B is plastically deformed in the direction of the two concave holes and bites into the periphery of the concave and convex portion 5A and into the front and back 5B and 5C. At this time, the gap between the connecting shaft 2B and the concave holes 2 is approximately the same as the amount of deformation of the protrusion 2B. There is no elongation of the turbine rotating shaft 2 which is in the position, and it is securely fixed at the specified position.

Next, to fix the compressor impeller 4, after fixing the impeller 3 to the turbine rotating shaft 2 and supporting it in the housing case 1 as shown in FIG. It is placed in a mold 8 and fixed to the rotating shaft 2. Here, the rotating shaft 2 has a knurling 2C at its tip and an annular concave surface 2D at the knurling base,
The compressor impeller 4 is arranged in a cone-like manner, with one end of a hollow shut 4A formed integrally with the compressor impeller fitting and facing each other.
The outer circumference of the hollow shirt 4A is squeezed by a mold 9 having an inner diameter smaller than its outer diameter, resulting in plastic deformation.That is, when the hollow mold 9 is press-fitted from the end face of the hollow shaft 4A, , hollow shirt made of aluminum material) 4A is gradually plastically deformed, and some of the material that cannot escape bites into the knurling 2C and flows into the annular concave surface 2D, preventing movement in the rotational and axial directions.

The coupling shaft of the turbine impeller coupled by the above method and one end of the turbine rotating shaft fixing the compressor impeller are securely fixed without being subjected to any deformation pressure or tensile force, respectively. Furthermore, when fixing, the two parts are brought into close contact while being plastically formed with a mold, so a product with good finishing accuracy can be obtained.

The shape of the fixed portion of the compressor impeller may be, in addition to the knurling shown in the above embodiment, a screw groove, a mesh groove, or the like. Of course, it is also possible to provide it in several stages in the axial direction, if necessary.

〔Effect of the invention〕

As described above, according to the present invention, a shaft-to-shaft joining method with high joining precision and product precision is provided.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional side view of a turbine supercharger using the present invention, Fig. 2 is a longitudinal sectional view of main parts showing the method of coupling the turbine impeller and the turbine rotating shaft in Fig. 1, and Fig. 3 is a partial cross-sectional side view of a turbine supercharger using the present invention. Same 1st
FIG. 4 is a longitudinal sectional view of a narrow portion showing a method of coupling the compressor impeller and the turbine rotation shaft in the figure, and FIG. 4 is a partially exploded enlarged view of FIG. 2.

Claims (1)

[Claims] 1. In a shaft-to-shaft coupling method in which a first shaft member and a second shaft member are fitted and joined together, the first member is provided with unevenness extending in the axial direction on the outer circumferential surface; A soft second part that fits with the outer diameter and has at least a joining part equal to or smaller than the above-mentioned member.
After fitting the second member to the first member, the material of the second member is pressed and plastically flowed with a mold in the first uneven portion and before and after the first uneven portion. A method for connecting shafts, characterized in that movement in the rotational direction is fixed by a material inserted in the circumferential direction of the shaft, and movement in the axial direction is fixed by material at both ends of the uneven axial direction.