JPH106119A - Machining method for radial flow impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the thickness of blade at the central part of the height of a blade and to improve efficiency. SOLUTION: Based on a relation between the projection line 13a of the central line of a ball end mill 12a to a meridian surface and the central line 16 of the rotary shaft 15 of an impeller 14 when the pressure surface side (the recessed side) 11a of a blade 11 is cut, a relation between the projection line 13b of the meridian surface of the central line of a ball end mill 12b and the central line 16 of the rotary shaft 15 of the impeller 14 when the negative pressure surface side (the protrusion side) 11b positioned facing the pressure surface side with the blade 11 nipped therebetween is established such that the projection line 13b of the meridian surface of the central line of the ball end mill 12b is inclined in a direction in which it approaches the central line 16 of the rotary shaft 15 in parallel to the central line and with this state, the blade 11 is cut. The negative pressure surface side 11b at a section orthogonal to the rotary shaft 15 of the blade 11 forms a curve. The thickness (t) of the blade 11 is decreased at the central part of the height (h) of the blade 11 to improve efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a radiating impeller of a turbocharger, a gas turbine, a centrifugal compressor or the like.

[Prior art]

[0002] As a method of processing a radiation impeller of a supercharger, a gas turbine, a centrifugal compressor, or the like, a special wooden mold is manufactured, and after the radiation impeller is cast, the blades are manually cut to finish. Processing was done. A conventional processing method will be described with reference to FIGS. FIG. 5 shows a cross section of the blade being cut, FIG. 6 shows a view taken along line VI-VI in FIG. 5, and FIG. 7 shows a relationship between the thickness and the height of the blade.

As shown in FIG. 5, a blade 1 of a radiation impeller is cut out using a side surface of a conical ball end mill 2. Projection line 3 on the meridian plane of the center line of ball end mill 2
Are made the same on the pressure side and the suction side of the blade 1. As shown in FIG. 6, among the trajectories of the center lines of the ball end mill 2 on the pressure surface side and the suction surface side of the blade 1, the cross-sectional shape of the blade 1 in the cross section including a pair of opposing pairs is changed from the hub to the tip It becomes trapezoidal up to.

[0004]

SUMMARY OF THE INVENTION A blade 1 is formed by a conventional processing method.
When cutting is performed, since the cross-sectional shape of the blade 1 becomes trapezoidal from the hub to the tip, the thickness t of the blade 1 linearly changes with respect to the height h of the blade 1 as shown in FIG. Change. on the other hand,
Regarding the strength of the wing 1, the stress at the root of the wing 1 is the highest,
The stress decreases in proportion to the square of the difference in height of any wing 1 from the tip of wing 1. Therefore, the thickness t of the central portion of the height of the wing 1 was too thick as a result. Therefore, the radiation impeller having the blades 1 cut by the conventional processing method has a low efficiency.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, a method of processing a radiant impeller according to the present invention is directed to a radiant impeller for cutting blades by cutting a side surface of a ball end mill having a conical blade surface. In the machining method of (1), the relationship between the projection line of the meridional plane of the center line of the ball end mill and the center line of the rotation axis of the impeller when cutting the pressure surface side of the blade is negative, which is opposed across the blade. The relationship between the projection line of the meridional plane of the center line of the ball end mill and the center line of the rotation axis of the impeller when cutting the pressure side is such that the center line of the ball end mill approaches parallel to the rotation axis of the impeller. By processing the blade with an inclination, the suction surface side in a cross section perpendicular to the rotation axis of the blade is formed to be curved. For this reason, the pressure distribution of the blade height is thinner at the center of the blade height than in the past, and the efficiency of the impeller is improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view for explaining a method of processing a radiation impeller according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II in FIG. 1 shows a view taken along line III-III in FIG. FIG. 4 shows the relationship between the height and the thickness of the wing.

As shown in FIG. 1, the blades 11 of the radiating impeller are cut out using the side surfaces of a conical ball end mill 12. When cutting the pressure surface side (concave side) 11a of the blade 11, the projection line 13 a of the center line of the ball end mill 12 a onto the meridian plane and the center line 16 of the rotating shaft 15 of the impeller 14 are related to each other. Negative pressure side (convex side) 1 opposite
The relationship between the projection line 13b of the meridian plane of the center line of the ball end mill 12b and the center line 16 of the rotation axis 15 of the impeller 14 when cutting 1b is obtained by rotating the projection line 13b of the meridian plane of the center line of the ball end mill 12b. The blade 11 is cut while being inclined in a direction approaching parallel to the center line 16 of the shaft 15.

FIG. 3 shows the wing 1 in a plane perpendicular to the projection line 13a.
1 shows a cross-sectional shape. As shown in FIG. 3, when the tip 17 and the hub 18 are simultaneously cut by the ball end mill 12b on the suction side 11b, the tip 17 and the hub 18 are cut straight. As a result, as shown in FIGS. 2 and 3, the thickness t of the blade 11 is reduced by Δt, and the thickness t of the blade 11 can be reduced at the center of the height h of the blade 11.
That is, as shown in FIG. 2, the suction surface side 11b in a cross section perpendicular to the rotation axis 15 of the blade 11 is formed so as to be curved. The relationship between the height h and the thickness t of the blade 11 at this time is as shown in FIG.

When the blade 11 is to be cut out by the above-described processing method, the blade 11 is automatically processed using a numerically controlled machine. The cast blade can be processed in the same manner. According to the processing method described above, the thickness t of the wing 11 can be reduced at the center of the height h of the wing 11, and the thickness t of the center of the height of the wing 11 is too thick as a result. And the efficiency can be improved.

[0010]

The method for machining a radiation impeller according to the present invention is directed to a method of cutting the pressure surface side of a blade by using a relationship between a projection line of a meridional plane of a center line of a ball end mill and a center line of a rotation axis of the impeller. On the other hand,
The relationship between the projection line of the meridional plane of the center line of the ball end mill and the center line of the rotation axis of the impeller when cutting the negative pressure surface side that faces the blade is sandwiched between the center line of the ball end mill and the rotation axis of the impeller. By machining the blade in a direction approaching parallel, the suction surface side in the cross section perpendicular to the rotation axis of the blade is formed so as to be curved, so the blade at the center of the blade height Can be made thinner, and the efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method of processing a radiation impeller according to an embodiment of the present invention.

FIG. 2 is a view taken along line II-II in FIG.

FIG. 3 is a view taken along the line III-III in FIG. 1;

FIG. 4 is a graph showing the relationship between the height and the thickness of a wing.

FIG. 5 is a cross-sectional view for explaining a conventional method of processing a radiation impeller.

FIG. 6 is a view taken along line VI-VI in FIG. 5;

FIG. 7 is a graph showing the relationship between the height and the thickness of the wing.

[Explanation of symbols]

 Reference Signs List 11 blade 11a suction side 11b pressure side 12 ball end mill 13 projection line 14 impeller 15 rotation axis 16 centerline 17 tip 18 hub

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Mikogami, 3000 Tana, Sagamihara-shi, Kanagawa Prefecture Mitsubishi Heavy Industries, Ltd.

Claims (1)

[Claims] 1. A method for processing a radial impeller in which a blade is cut by cutting a side surface of a ball end mill having a conical blade surface, wherein a center line of the ball end mill when cutting the pressure surface side of the blade. With respect to the relationship between the projection line of the meridional plane of the impeller and the center line of the rotation axis of the impeller, the projection line of the meridional plane of the center line of the ball end mill and the impeller when cutting the suction side opposite to the blade. The relationship of the center line of the rotation axis of the blade end mill is inclined in a direction in which the center line of the ball end mill approaches parallel to the rotation axis of the impeller, so that the blade is machined. A method for processing a radiation impeller, characterized in that the pressure surface side is formed to be curved.