JP2003049663A - Manufacturing method for variable vane in vgs(variable geometry system) type turbocharger and variable vane manufactured by same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new manufacturing method providing a preform to become an original form of a variable vane by casting and constantly and massively manufacturing stable and high-quality level variable vanes without using any cutting and welding. SOLUTION: This manufacturing method for the variable vane 1 is characterized by having a preparation process for the preform for integrally forming a vane part 11 and a shaft part 12 by casting, an HIP(Hot Isostatic Pressing) process for treating the injection molded preform by hot hydrostatic pressure pressing and improving the density of the preform, a rolling process for pressurizing the shaft part 12 of the preform onto a pair of dies and forming it into a prescribed-thickness diameter, a process for polishing the end face of the vane part 11 and forming the vane part 11 into a prescribed vane height (h), and a barrel process for wholly polishing the surfaces of the shaft part 12 and the vane part 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger used in an automobile engine or the like,
In particular, the present invention relates to a novel manufacturing method capable of eliminating cutting and welding altogether when manufacturing a variable blade incorporated in this product.

[0002]

BACKGROUND OF THE INVENTION A turbocharger is known as a supercharger used as a means for increasing the output and improving the performance of an automobile engine. This turbocharger drives a turbine by the exhaust energy of the engine, It is a device that rotates the compressor by the output and brings the engine into a supercharged state that is higher than natural intake. By the way, in this turbocharger, when the engine is rotating at a low speed, the exhaust turbine hardly works due to a decrease in the exhaust flow rate, and therefore, in the case of an engine that can rotate up to a high rotation range, the turbine has a feeling of rattling until it rotates efficiently, It was inevitable that the so-called turbo lag, etc., required for the subsequent blowing up of the air all at once. Also, the diesel engine, which has a low engine speed, has a drawback that it is difficult to obtain a turbo effect.

For this reason, a VGS type turbocharger has been developed which operates efficiently even in a low rotation range. This is a device in which a small exhaust flow rate is narrowed down by variable blades (blades), the speed of exhaust is increased, and the work of the exhaust turbine is increased, so that high output can be exhibited even at low speed rotation. Therefore, the VGS type turbocharger requires a variable blade variable mechanism and the like, and the peripheral components also have to be more complicated in shape and the like than the conventional ones. In the manufacture of such a variable blade for a VGS type turbocharger, conventionally, for example, a precision casting method typified by lost wax casting has been used. This is because the variable blade's original shape (form material) is cast almost as the intended product (actually, it is slightly larger than the actual product size), then this shape material is cut appropriately, and finally the blade part The shaft part is finished into a desired shape and size.

However, the cast material cast by the lost wax method can be approximated to the actual product size almost faithfully, and a so-called near net shape can be obtained, but the shape and size accuracy is not always good, and There was a problem that the variations among individual products were noticeable. Therefore, in the cutting process of the blank after casting,
The cutting allowance is often different for each product, and the setting of the cutting allowance may be complicated. In addition, since this type of turbo equipment is generally used under high temperature and exhaust gas atmosphere, heat resistant stainless steel such as SUS310S having excellent heat resistance and oxidation resistance is also applied to the variable blades. However, such a material is generally difficult to cut, and there is a problem that the cutting itself takes a long time and the processing is troublesome. Furthermore, about 10 to 15 variable vanes are required for one turbocharger, so when actually producing about 30,000 cars per month,
It was necessary to manufacture 300,000 to 450,000 variable blades per month, and the cutting process was not enough to handle it (the cutting process was limited to about 500 per day).

Under the circumstances, a method for manufacturing a variable vane, which eliminates the cutting work, has been developed, for example, Japanese Patent Laid-Open No. 2000-14.
No. 5470, "Variable vanes applied to variable vane turbocharger and manufacturing method thereof". This Japanese Patent Laid-Open No. 2000-145470 discloses a method in which a variable blade is first divided into a blade portion and a shaft portion and then formed, and then welded, and the cutting is not required at all, and accordingly, a proper evaluation is made. Although obtained, there was still room for further development.

That is, in the method of manufacturing the variable blade by welding the blade portion and the shaft portion, which are divided in advance, it is extremely difficult to always weld the blade portion and the shaft portion at a constant angle.
The accuracy may vary. Also, even if the shape itself of the blade and the shaft in the single product state can be formed with high accuracy, the welding heat and welding marks (welding beads) will have a bad effect, and the desired dimensional accuracy cannot be obtained as the final product. As a result, it has not reached the stage where mass production of stable, high-quality variable blades has always been reached.
In recent years, particularly in diesel vehicles, the exhaust gas discharged into the atmosphere is strongly regulated from the viewpoint of environmental protection and the like, and NO _x and particulate matter ( VG that can improve the efficiency of the engine even in the low speed range to reduce PM)
Mass production of the S-type turbocharger was highly desired.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and a raw material which is a prototype of a variable blade is obtained by metal injection molding and cut into the raw material. This is an attempt to develop a new manufacturing method that enables mass production of stable and high quality variable blades without any welding or welding.

[0008]

That is, a method for manufacturing a variable vane in a VGS type turbocharger according to a first aspect of the present invention comprises a shaft portion which is a center of rotation and a vane portion which substantially regulates a flow rate of exhaust gas. The relatively small amount of exhaust gas emitted from the engine is appropriately narrowed down, the speed of the exhaust gas is amplified, the exhaust turbine is rotated by the energy of the exhaust gas, and the compressor directly connected to this exhaust turbine produces more than natural intake air. In order to manufacture a variable blade to be incorporated into a VGS type turbocharger that enables the engine to deliver high output even at low speed rotation, the process involves the metal injection molding of the blade and shaft. The process of preparing the raw material, which is to form the metal material that is integrally provided, and the hot isostatic pressing process for the injection-molded raw material, The HIP process for increasing the degree of flexibility, the rolling process for pressing the shaft part of the blank into a pair of dies and processing it to the desired diameter, and the end face of the blade part is polished to make the blade part the desired blade height. And a barrel process for polishing the entire surface of the shaft and wings. According to the present invention, the base material of the variable blade is obtained by metal injection molding, and the variable blade can be mass-produced efficiently without performing cutting or welding on the base material. .

Further, in the method for manufacturing a variable blade in a VGS type turbocharger according to claim 2, in addition to the requirements according to claim 1, in the rolling step, the rolling allowance is set to 0.05 to 0.1 mm. It is characterized in that it suppresses the axial elongation caused by rolling. According to this invention, the axial elongation caused by rolling is 0.05 m due to the extremely small rolling allowance.
It can be suppressed to m or less (substantially no correction is required for this dimension), and the cutting process which has been conventionally performed to correct the axial elongation can be eliminated. Therefore, the cutting process can be completely eliminated from the manufacturing process of the variable vanes, which makes the mass production of the variable vanes more realistic. It should be noted that simply switching the machining of the shaft portion from cutting to rolling causes axial elongation due to rolling, and new cutting may be required to correct this. In the form, it has also been devised to suppress axial elongation.

According to a third aspect of the present invention, in addition to the requirements of the first or second aspect, in the method for manufacturing a variable blade in a VGS type turbocharger, in the step of preparing the raw material, a spherical gap between metal particles is used. It is characterized in that sintering is carried out so that a certain closed cell is finely and uniformly generated. According to this invention, the porosity of the metal material obtained by metal injection molding is reduced, and the strength of the raw material can be increased. That is, it is possible to overcome the high porosity, which is one of the drawbacks of metal injection molding, and it is possible to practically apply the base material formed by injection molding. Further, due to the reduced porosity, the dimensional accuracy is improved, and the shaped material to be molded can have a near net shape closer to the target variable blade. Therefore, the rolling allowance and the like can be further suppressed, and the rolling process and the like can be simplified.

A method for manufacturing a variable blade in a VGS type turbocharger according to a fourth aspect of the present invention is the method according to the first aspect.
In addition to the requirements described in 2 or 3, in the step of preparing the base material, the shape of the metal powder for injection molding is made spherical and fine, and the high temperature rotary bending fatigue property of the base material is improved. It consists of According to this invention, the high temperature rotary bending fatigue of the metal material obtained by injection molding is improved. That is, it is possible to overcome the high-temperature rotary bending fatigue property, which is one of the drawbacks of metal injection molding, and it is possible to actually apply the raw material obtained by injection molding. It should be noted that, simply by switching from lost wax to metal injection molding in obtaining a raw material, such inconveniences associated with metal injection molding occur, and a raw material that can be mass-produced practically cannot be obtained. A device for overcoming such inconvenience is also provided.

Further, the variable blade in the VGS type turbocharger according to claim 5 comprises a shaft portion which is a center of rotation and a blade portion which substantially adjusts a flow rate of exhaust gas, and is relatively discharged from the engine. A small amount of exhaust gas is appropriately narrowed down, the speed of the exhaust gas is amplified, the exhaust turbine energy is used to turn the exhaust turbine, and a compressor directly connected to the exhaust turbine sends air above the natural intake to the engine, and at low speed. A variable wing incorporated in a VGS type turbocharger which enables the engine to exhibit high output.
It is characterized by being manufactured by the manufacturing method described. According to the present invention, the variable blade as a mass-produced product can be stably supplied to the market because it can be manufactured without performing cutting, welding, etc., which required a great amount of time for processing. By the way, with the conventional method that mainly relies on cutting, 5
In the present invention, the production amount was about 00 pieces, but in the present invention, about 5000 pieces can be mass-produced per day. In addition, mass-produced variable blades can be obtained with high dimensional accuracy by devising the injection molding of the blank material and by devising a rolling allowance to keep the axial elongation within an allowable range.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments. In the description, the variable vane 1 will be described together with the exhaust guide assembly A in the VGS type turbocharger to which the variable vane 1 according to the present invention is applied, and then the variable vane 1 according to the present invention.
The manufacturing method of will be described. The exhaust guide assembly A adjusts the exhaust gas flow rate by appropriately narrowing the exhaust gas G when the engine is rotating at a low speed, and is provided on the outer periphery of the exhaust turbine T as shown in FIG. A plurality of variable blades 1 for setting the flow rate, a turbine frame 2 for rotatably holding the variable blade 1, and a variable mechanism 3 for rotating the variable blade 1 by a certain angle to appropriately set the flow rate of the exhaust gas G are provided. It consists of. Each component will be described below.

First, the variable blade 1 will be described. As an example, as shown in FIG. 1, a plurality of these are arranged in an arc shape along the outer periphery of the exhaust turbine T (one exhaust guide assembly A
Approximately ten to fifteen of them are disposed, and each of them is rotated by approximately the same degree to appropriately adjust the exhaust gas flow rate. Each variable blade 1 comprises a blade portion 11 and a shaft portion 12. The blade portion 11 is formed so as to have a constant width mainly according to the width dimension of the exhaust turbine T, the cross-section in the width direction thereof is formed into a substantially blade shape, and the exhaust gas G is effectively exhaust turbine. It is configured to go to T. Here, the width dimension of the blade portion 11 is referred to as a blade height h for convenience. In addition, the shaft portion 12 is formed so as to be continuous with the wing portion 11 integrally, and is a portion corresponding to a rotating shaft when the wing portion 11 is moved.

At the connecting portion between the blade portion 11 and the shaft portion 12, there is provided a taper portion 13 that narrows from the shaft portion 12 toward the blade portion 11, and a flange portion 14 having a diameter slightly larger than that of the shaft portion 12. Are formed to be continuous. The bottom surface of the collar portion 14 is formed substantially on the same plane as the end surface of the blade portion 11 on the shaft portion 12 side, and this plane serves as a sliding surface when the variable blade 1 is attached to the turbine frame 2, The smooth rotating state of the blade 1 is ensured. Furthermore, at the tip of the shaft 12,
A reference surface 15 is formed which serves as a reference for the mounting state of the variable blade 1. The reference surface 15 is a portion fixed to the variable mechanism 3 described later by crimping or the like, and as an example, FIG.
As shown in FIG. 2, the plane in which the shaft portion 12 is cut out in a facing manner is formed with a substantially constant inclination with respect to the blade portion 11.

Next, the turbine frame 2 will be described. This is configured as a frame member that rotatably holds a plurality of variable blades 1. As an example, as shown in FIG. 1, the variable blade 1 is sandwiched by a frame segment 21 and a holding member 22. Is configured as follows. The frame segment 21 is provided with a flange portion 23 that receives the shaft portion 12 of the variable blade 1 and a boss portion 24 that fits the variable mechanism 3 described later on the outer circumference. Due to such a structure, the flange portion 23 is formed with the same number of receiving holes 25 as the variable blades 1 at the peripheral portion at equal intervals. Further, the holding member 22 is formed in a disk shape having an opening in the central portion as shown in FIG. The dimension of the variable blade 1 sandwiched between the frame segment 21 and the holding member 22 is substantially constant (generally, the blade width of the variable blade 1 is approximately constant so that the blade portion 11 of the variable blade 1 can always be smoothly rotated. The caulking pins 26 are provided at four places on the outer peripheral portion of the receiving hole 25 as an example.
The dimension between both members is maintained by. Here, the holes formed in the frame segment 21 and the holding member 22 to receive the crimping pins 26 are referred to as pin holes 27.

In this embodiment, the flange portion 23 of the frame segment 21 has two flange portions, that is, a flange portion 23A having substantially the same diameter as the holding member 22 and a flange portion 23B having a diameter slightly larger than the holding member 22. , Which are made of the same material,
In the case where processing with the same member becomes complicated, it is also possible to form two flange portions having different diameters by dividing them and then to join them by caulking or brazing.

Next, the variable mechanism 3 will be described. This is provided on the outer peripheral side of the boss portion 24 of the turbine frame 2 and rotates the variable blade 1 in order to adjust the exhaust flow rate. As an example, as shown in FIG. The variable blade 1 includes a rotating member 31 that causes the variable blade 1 to rotate, and a transmission member 32 that transmits the rotation to the variable blade 1. The rotating member 31 is formed in a substantially disc shape with an opening in the central portion as shown in the figure, and the same number of transmitting members 32 as the variable blades 1 are provided at equal intervals on the peripheral portion thereof. The transmission member 32 includes a drive element 32A rotatably attached to the rotating member 31 and the variable blade 1.
Element 32 fixedly mounted on the reference plane 15 of the
B is included, and the rotation is transmitted in a state where the drive element 32A and the passive element 32B are connected. Specifically, a rectangular piece-shaped drive element 32A is rotatably pinned to the rotating member 31, and a passive element 32B formed in a substantially U shape so as to receive the drive element 32A is variable. Fixed to the reference surface 15 at the tip of the wing 1, and the square-piece-shaped drive element 32A is replaced by the U-shaped passive element 32.
The rotation member 31 is fitted in the B and is engaged with both.
Is attached to the boss portion 24.

In the initial state in which a plurality of variable vanes 1 are attached, in order to align them in a circumferential shape, each variable vane 1 and the passive element 32B need to be attached at a substantially constant angle. In the above embodiment, the reference surface 15 of the variable vane 1 mainly plays this role. Further, when the rotating member 31 is simply fitted in the boss portion 24, when the rotating member 31 is slightly separated from the turbine frame 2,
Since there is concern that the engagement of the transmission member 32 may be released, in order to prevent this, a ring 33 or the like is provided so as to sandwich the rotating member 31 from the opposite side of the turbine frame 2,
The rotation member 31 is given a tendency to be pressed toward the turbine frame 2 side. With such a configuration, when the engine rotates at a low speed, the rotating member 31 of the variable mechanism 3 is appropriately rotated, and the shaft portion 12 is moved through the transmission member 32.
And the variable blade 1 is rotated as shown in FIG. 1, the exhaust gas G is appropriately narrowed, and the exhaust flow rate is adjusted.

An example of the exhaust guide assembly A to which the variable vane 1 according to the present invention is applied is configured as described above, and a method for manufacturing the variable vane 1 will be described below. (1) Forming material preparation step In this step, the original shape (formation material) of the variable blade 1 is obtained by metal injection molding, and the shape material is slightly larger than the variable blade 1 in the completed state. Although formed, it is formed into a so-called near net shape having a shape and dimensions that are almost close to the completed state. Metal injection molding is essentially
This is the same as the conventionally known general injection molding of general synthetic resin (plastic), and for example, metal powder (material) such as iron or titanium.
A binder (mainly an additive that binds metal powders together, as an example, a mixture of polyethylene resin, wax, and phthalate ester) is kneaded to impart plasticity, and then injected into a mold to obtain an appropriate shape. It is what hardens. Then, after removing the binder, it is sintered to obtain a raw material having a desired shape.

In the metal injection molding, the porosity of the formed raw material is generally higher than that of the solid material, and particularly in the case of heat resistant high alloy material, the bulk density is insufficient and the high temperature It had the drawback of being inferior in bending fatigue. Here, the vacancy is a kind of cavity (a large number of aggregates of point defects, which become microscopic (micro) cracks when they are connected and aggregated) in a crystal of a metal material, etc., and this ratio is too high. And it has a bad influence on metal materials.
For this reason, in this embodiment, in order to make the closed cells (spherical gaps between the metal particles) small and uniform, the sintering is performed for a long time. Specifically, for example, when SUS310S having a melting point of 1500 ° C is applied, sintering is performed at 1300 ° C for a relatively long time of about 2 hours.

(2) HIP step By performing the above-mentioned sintering, the porosity of the raw material can be reduced and the bulk density can be improved. (Hot Isostati
In the step (abbreviated as c Pressing), hot isostatic pressing is performed to achieve a higher density. Specifically, the template material is isotropically applied with a pressure of about 100 MPa (1000 atm) while the template material is heated to, for example, about 1300 ° C. The applicant confirmed that the above-mentioned sintering, HIP treatment, etc., increased the closed cells from about 100 μm before sintering to about 10 μm after sintering, improving the bulk density by about 5%. Has been done. The improvement of the bulk density improves the strength of the raw material, improves the dimensional accuracy, and obtains the near-net shaped raw material.

Further, in the present embodiment, a technical device for making the metal powder for injection molding spherical and fine and improving the high temperature rotary bending fatigue resistance of the shaped material to be molded is also provided. Here, in making the metal powder spherical and fine,
For example, a molten metal is ejected from a nozzle, a high-speed fluid such as air or water is caused to act on the molten metal, the metal is divided into a large number of droplets by the impact force of the high-speed fluid, and then cooled and solidified to obtain a metal powder. The air atomizing method and the water atomizing method are applied. And in such an atomizing method, by appropriately changing the shape and diameter of the nozzle for ejecting the molten metal, the discharge rate of air or water acting on the molten metal, the cooling rate, etc., the metal of the desired size can be obtained. A powder is obtained. By the way, SUS
It has been confirmed by the applicant of the present invention that when the metal powder of 310S is finely pulverized to about 200 μm and sintered, the high-temperature rotary bending fatigue property is improved by about 20%.

(3) Rolling Step This step is a step of pressing the shaft portion 12 of the blank, which has finished the HIP step, against a pair of dies and processing it into a desired diameter. Note that the rolling allowance in this embodiment is suppressed to an extremely small dimension of about 0.05 to 0.1 mm as an example, whereby the axial elongation caused by rolling is
As an example, it can be suppressed to 0.05 mm (upper limit value in consideration of variations in processing) or less. By the way, if this degree of axial elongation is required, substantial post-processing to correct this is not necessary, and this eliminates the cutting work that was conventionally performed to correct axial elongation. is there. Here, the relationship between the rolling allowance and the axial elongation is shown in FIG. 3. In this figure, the straight line passing through the point where the axial elongation becomes 0.05 mm when the rolling allowance is 0.1 mm is the upper limit of the variation. It becomes a straight line, and the range of variation is shown including the standard machining line in the hatched portion below it (in the figure, the range of variation above and below the standard machining line is indicated by different hatching).

Of course, the rolling allowance of the shaft portion 12 of the raw material can be suppressed within the above-mentioned dimensions because it is technically possible to improve the bulk density of the raw material in addition to obtaining the raw material by metal injection molding. One of the reasons is that the material can be formed into a near-net shape due to ingenuity. To put it the other way around, no matter how much the raw material that is far from the actual product dimensions is rolled, the larger the rolling allowance, the greater the axial elongation. In some cases, a new cutting process is required to correct this axial elongation. Therefore, the original purpose of switching to the rolling process cannot be achieved.

(4) Polishing of blade end face (blade height polishing) As described in the description of the exhaust guide assembly A, the blade portion 11 is mounted between the frame segment 21 and the holding member 22 in the attached state. Even if it is sandwiched, a smooth rotating state is ensured. Therefore, in this process, the frame segment 21 in the wing portion 11 is
Side (shaft 12 side) end surface and holding member 2 facing this
The blade height h is finished to a desired dimensional accuracy by polishing both the end surface on the second side and the both sides. Of course, in view of the function of the variable blade 1, if either one of the two end surfaces of the blade portion 11 can be polished, only one of them may be polished.

(5) Barrel process In this process, both end faces of the blade portion 11 are polished, and a metal material (variable blade) having a desired blade height h is entirely surface-polished. In this process, a material and an additive called a medium are put into a barrel container, and the barrel container is rotated or vibrated to collide the metal material with the medium to finish the surface of the metal material.

[0028]

According to the invention described in claim 1 or 5, the variable vane 1 can be manufactured without performing cutting, welding, etc., which conventionally required a great amount of time for processing. The variable blade 1 can be stably supplied to the market. Specifically, by eliminating the cutting process, about 5000 variable blades 1 can be manufactured per day, which is sufficient for mass production. Further, the variable blade 1 manufactured can have a high dimensional accuracy due to technical measures for improving the bulk density of the raw material.

Further, according to the second aspect of the present invention, due to the fact that the rolling allowance is set as small as possible, the axial elongation accompanying the rolling does not require a subsequent correction process (cutting). Can be suppressed to Therefore, the cutting process can be completely eliminated from the manufacturing process of the variable vanes 1, and the mass production of the variable vanes 1 can be further realized.

Furthermore, according to the third aspect of the present invention, the porosity, which is one of the drawbacks of metal injection molding, can be reduced, and a near-net shaped molding material closer to the actual product can be obtained. . Therefore, the rolling allowance can be suppressed to a smaller size.

According to the fourth aspect of the present invention, the high-temperature rotary bending fatigue property, which is one of the drawbacks of metal injection molding, can be improved, and the method for forming a blank by injection molding becomes a reality.

[Brief description of drawings]

FIG. 1 is a perspective view (a) showing a VGS type turbocharger incorporating a variable vane according to the present invention, and an exploded perspective view (b) showing an exhaust guide assembly.

FIG. 2 is a front view and a left side view showing a variable vane according to the present invention.

FIG. 3 is a graph showing the relationship between the rolling allowance when rolling the shaft portion of the variable vane and the accompanying axial elongation.

[Explanation of symbols]

1 variable wings 2 turbine frame 3 variable mechanism 11 wings 12 Shaft 13 Tapered part 14 Tsubabe 15 Reference plane 21 frame segments 22 Holding member 23 Flange 23A Flange (small) 23B Flange (large) 24 Boss 25 receiving hole 26 Caulking pins 27 pin hole 31 Rotating member 32 transmission member 32A drive element 32B passive element 33 ring A Exhaust guide assembly G exhaust gas h blade height T exhaust turbine

Claims (5)

[Claims] 1. A shaft having a center of rotation and a wing that substantially adjusts a flow rate of exhaust gas, and appropriately narrows a relatively small amount of exhaust gas discharged from an engine to amplify the speed of the exhaust gas. VGS type that rotates the exhaust turbine with the energy of the exhaust gas, and sends the air more than naturally aspirated to the engine by the compressor directly connected to this exhaust turbine, so that the engine can exhibit high output even at low speed rotation. In manufacturing variable blades to be installed in the turbocharger of, the process was to prepare a raw material by metal injection molding to mold a metal material with the blade and shaft integrally, and injection molding Hot isostatic pressing is applied to the base material,
The HIP process for increasing the density of the base material, the rolling process for pressing the shaft part of the base material against a pair of dies and processing it into the desired diameter, and the end face of the blade part is polished to remove the blade part. A method of manufacturing a variable blade for a VGS type turbocharger, comprising: a step of forming a desired blade height; and a barrel step of polishing the entire surface of a shaft portion, a blade portion and the like. 2. The rolling allowance is set to 0.
5. The V according to claim 1, characterized in that the axial elongation is suppressed to 05 to 0.1 mm so as to suppress axial elongation caused by rolling.
A method for manufacturing a variable blade in a GS type turbocharger. 3. In the step of preparing the shaped material, the sintering is performed so that closed cells, which are spherical gaps between the metal particles, are finely and uniformly generated. 2. A method for manufacturing a variable blade in a VGS type turbocharger according to 2. 4. The step of preparing the raw material is characterized in that the shape of the metal powder for injection molding is made spherical and fine to improve the high temperature rotary bending fatigue resistance of the raw material. 4. A method for manufacturing a variable blade in a VGS type turbocharger according to 1, 2 or 3. 5. The speed of the exhaust gas is amplified by appropriately squeezing a relatively small amount of exhaust gas discharged from the engine, which comprises a shaft portion serving as a center of rotation and a wing portion for substantially adjusting the flow rate of exhaust gas. Then, the exhaust turbine energy is used to rotate the exhaust turbine, and a compressor directly connected to the exhaust turbine blows air above the naturally aspirated air into the engine so that the engine can exhibit high output even at low speed rotation.
A variable blade incorporated in an S type turbocharger, which is manufactured by the manufacturing method according to claim 1, 2, 3 or 4.