JP2003049655A - 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 for the preform. SOLUTION: This manufacturing method for the variable vane 1 is characterized by having a preparation process for the preform for providing a metal material integrally having a vane part 11 and a shaft part 12 by casting, a rolling process for pressurizing the shaft part 12 of the cast 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 above-described method of sequentially cutting the variable blade material has a problem in the following points. That is, this type of turbo device
Since it is generally used under high temperature and exhaust gas atmosphere, the variable blade also has excellent heat resistance and oxidation resistance.
Heat-resistant stainless steel such as 310S is applied, but such a material is generally a material that is difficult to cut,
There is a problem that it takes a long time for cutting and it takes time to process. In addition, about 10 to 15 variable blades are required for one turbocharger, so if the actual monthly production of about 30,000 cars is carried out, the variable blades will be 30 times a month.
It was necessary to manufacture 10,000 to 450,000 pieces, and the cutting process was not enough to meet the demand.
The limit was around 00).

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. Further, 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 the welding mark (welding bead) adversely affect the desired dimensional accuracy as the final product. For this reason, the current situation is that we have not reached the stage where we can mass-produce stable, high-quality variable blades at all times. 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 ( It has been earnestly desired to mass-produce a VGS type turbocharger that can improve the efficiency of the engine even in a low rotation range in order to reduce PM).

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and a cast material which is a prototype of a variable blade is obtained by casting, and a cutting or welding is performed on the cast material. This is an attempt to develop a new manufacturing method that can actually mass-produce variable blades that are always stable and have a high quality level without performing any of the above.

[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 in a VGS type turbocharger that enables the engine to deliver high output even at low speeds, the process is to cast the blade and shaft together. The process of preparing the raw material to obtain the alloy material provided, and the process of pressing the shaft of the cast raw material into a pair of dies and processing it into the desired diameter It is characterized by including a step, a step of polishing the end surface of the blade portion to form the blade portion at a desired blade height, and a barrel step of polishing the entire surface of the shaft portion and the blade portion. It consists of According to the present invention, cutting and welding can be eliminated from the manufacturing process of the variable blade, which contributes to efficient manufacturing of the variable blade. Also, it will be possible to mass-produce variable wings.

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 and suppresses the axial elongation dimension caused by rolling. According to this invention, the axial elongation caused by rolling is 0.0 because the rolling allowance is set to be extremely small.
It can be suppressed to 5 mm 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 variable blade manufacturing process,
Make variable wing mass production 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, the method for manufacturing a variable blade in a VGS type turbocharger is characterized in that in the step of preparing the raw material, heat-resistant steel (alloy) is used in casting. ) Is used as the main base material, and C (carbon) and S contained are applied.
Each weight% of i (silicon) and O (oxygen) is 0.05 to
0.5%, 0.5 to 1.5% and 0.01 to 0.1% are used to improve the flowability of the molten metal cast into the mold. According to the present invention, in order to improve the flowability of the raw material to be cast, the shaped material obtained by casting has a so-called near net shape, which is closer in shape and size 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 raw material, either one or both of the mold and the raw material is cooled to shorten the time from casting the molten metal to crushing the die. However, it is characterized in that the solidification structure of the shaped material is made fine. According to this invention, since the solidification structure of the cast material obtained by casting is made finer, generally, sharp edges (metals on the surface of the shaft portion due to the rolling of the shaft portion are likely to occur in the cast material in the rolling process. The raw material undergoes plastic flow, and an acute angle portion formed in a protruding state from the tip of the shaft portion is effectively suppressed, the rolling process and the like are facilitated, and a product having a size closer to the intended product is obtained.

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, since the variable blade can be manufactured without performing cutting, welding, etc., which required a great amount of time for processing, the variable blade as a mass-produced product can be stably supplied to the market. By the way, in the conventional method that mainly relied on cutting,
In the present embodiment, the production amount of only about 500 pieces per day can be mass-produced at about 5000 pieces per day. In addition, mass-produced variable blades can be obtained with high dimensional accuracy by devising the casting of the blanks and devising the rolling allowance to keep the axial elongation within the 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 constituted as described above, and a method for manufacturing the variable vane 1 will be described below. (1) Casting process for forming material In this process, the original shape (forming material) of the variable blade 1 integrally including the blade portion 11 and the shaft portion 12 is formed by a precision casting method typified by lost wax casting. In the step of obtaining, the material is cast so as to have a shape and dimensions that are substantially close to the finished state while being formed somewhat larger than the variable blade 1 in the finished state. It is generally known that the lost wax method itself can faithfully reproduce a relatively complicated shape, but in the present embodiment, when casting,
The flowability of the raw material to be cast is improved so that the shape and dimensional accuracy of the raw material can be brought closer to the finished variable blade 1.

Specifically, a virgin material is applied to a raw material to be cast (heat-resistant material such as SUS310S), and the amount of C (carbon) contained in this virgin material is 0.05.
~ 0.5%, Si (silicon) amount 0.5 to 1.5%, O
The amount of (oxygen) is adjusted to 0.01 to 0.1% (the addition amount of each component indicates% by weight). It has been confirmed by the present applicant that the viscous fluidity of the Stokes flow is improved by at least about 20 to 40% by optimizing the amounts of C, Si, and O in this manner.

Further, by quenching one or both of the mold and the raw material, the time until the crushing of the die is shortened and the solidified structure of the raw material is made fine.
Specifically, for example, before and after casting, water is sprayed on the mold to cool it, and the time required for crushing the mold is shortened to, for example, 1 hour or less (normal air cooling takes 1 to 4 hours). At this time, only the mold is cooled in the pre-cooling before the casting, and both the mold and the base material are cooled in the cooling after the casting. Needless to say, the quenching is performed within a range in which the mold does not cause thermal stress cracking. If it is not necessary to cool before and after casting, either one may be used, or if it is desired to further enhance the cooling effect, in addition to cooling both before and after casting, the material removed from the mold It is also possible to spray cooling water on. And by making the solidification structure of the shaped material fine in this way, it is intended to prevent the sharp edge from occurring in the shaped material as much as possible during the subsequent rolling processing, making it easier to perform the rolling processing, etc. To do.

(2) Rolling Step This step is a step of pressing the shaft portion 12 of the cast blank into a pair of dies and processing it into a desired diameter. The rolling allowance in this embodiment is about 0.
It can be suppressed to about 0.05 to 0.1 mm, whereby the axial elongation caused by rolling can be suppressed to, for example, 0.05 mm (upper limit in consideration of processing variations) or less. By the way, if this degree of axial elongation is required, substantial post-processing to correct this is not necessary,
It eliminates the cutting that was often done to correct axial elongation. 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 after casting can be suppressed within the above-mentioned dimensions in addition to casting the raw material by the lost wax method, and improving the flowability of the raw material to be cast. It is possible to obtain the raw material in a state closer to the actual product size due to such 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 greater the rolling allowance, the greater the axial elongation.
In some cases, a new cutting process is required to correct this axial elongation, and the original purpose of switching to the rolling process cannot be achieved.

(3) 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 mounted 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.

(4) Barrel process In this process, both end faces of the blade portion 11 are polished, and the entire surface of a metal material (variable blade) having a desired blade height h is 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.

[0027]

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 by devising the casting of the blank material and devising a rolling allowance for suppressing the axial elongation within the allowable range.

According to the second aspect of the invention, because the rolling allowance is set to be as small as possible, the axial elongation accompanying the rolling does not require correction by later cutting. Can be suppressed. 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.

Further, according to the third aspect of the present invention, since the molten metal flowability is improved in casting, the casting material obtained by casting is a near-net shaped casting material closer to the actual product. Is obtained, and the rolling allowance can be suppressed to a smaller size.

According to the invention as set forth in claim 4, since a shaped material having a fine solidification structure can be cast, generally, sharp edges which are likely to occur in the shaped material in the rolling process are effectively suppressed, and The variable blade 1 can be formed with higher accuracy.

[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 turbochargers of, the process is to prepare an alloy material that integrally includes a blade and a shaft by casting, and to prepare the material and the cast material. Rolling process of pressing the shaft part to a pair of dies and processing it to a desired diameter, polishing the end surface of the blade part and forming the blade part to the desired blade height, shaft part and blade part Etc. overall Method for manufacturing a variable vane in VGS type turbocharger, characterized in that it comprises a barrel process of surface polishing. 2. The rolling allowance is set to 0.
The variable blade manufacturing method for a VGS type turbocharger according to claim 1, characterized in that the axial elongation dimension caused by rolling is suppressed to a value of 05 to 0.1 mm. 3. In the step of preparing the shaped material, a virgin material containing heat-resistant steel (alloy) as a main base material is applied in casting, and C (carbon), Si (silicon),
Each weight percent of O (oxygen) is 0.05-0.5%, 0.
The VGS type turbocharger according to claim 1 or 2, wherein the flow rate of the molten metal to be cast into the mold is improved by setting the content to 5 to 1.5% and 0.01 to 0.1%. Variable wing manufacturing method. 4. In the step of preparing the raw material, either one or both of the mold and the raw material is cooled to shorten the time from casting the molten metal to crushing the die, The method for manufacturing a variable blade in a VGS type turbocharger according to claim 1, 2 or 3, wherein the solidified structure of the material is made fine. 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.