JP2011157816A - Method of manufacturing variable vane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a variable vane, capable of setting the dimensions of a shaft part and a blade part with desired dimensional precisions without cutting work. <P>SOLUTION: A sinter is prepared such that, with respect to the target dimensions of a final product, the height of the blade part 2 ranges within +0.3% to +0.9%, the thickness of the blade part 2 ranges within -0.6% to -0.0%, the diameter of the shaft part 3 ranges within +0.3% to +0.9%, the length from the lower end of the blade part 2 to the lower end of the shaft part 3 ranges within -0.6% to -0.0%, and a sintering density is 95% or more of a relative density. In the sinter, the blade part 2 is set to desired product dimensions in the height direction and in the thickness direction at the same time in a first pressing process; the coaxiality between the blade part 2 and the shaft part 3 is set to a desired product dimension in a second pressing process; and the roundness of the shaft part 3 is set to a desired product dimension in a third pressing process. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a variable vane incorporated in a turbocharger used in an automobile engine or the like. More specifically, for a sintered product obtained by metal powder injection molding (MIM method), a mold for correcting the height and thickness of the wing part, a mold for correcting the shape of the wing part, and a mold for correcting the shaft part It is related with the manufacturing method of the variable vane which can be pressed by this and can make a wing | blade part and a shaft part into a predetermined dimension without cutting.

Turbochargers used in automobile engines, etc., amplify the exhaust gas flow rate so that the engine can efficiently obtain output even at low speed rotation, and the exhaust side turbine rotates using this exhaust energy. The engine is designed to rotate the intake side turbine directly connected to the exhaust side turbine to force air into the engine, and use multiple variable vanes as components to adjust the exhaust gas flow rate and flow velocity. I have.
This variable vane is composed of a central axis of rotation and a wing portion for adjusting the flow rate and flow velocity of exhaust gas, and the wing portion becomes thinner toward the tip.

  Conventionally, this variable vane has been manufactured by cutting, but the processing time is very long and the efficiency is as low as 100 to 500 per day per processing machine.

  Therefore, several production methods are presented. In Patent Document 1, a steel material as a material is manufactured by a cold forging process and a polishing process. In Patent Document 2, a product is manufactured by using a lost wax or a material manufactured by the MIM method, using a rolling method for the shaft and a press in the height direction. In Patent Document 3, a product is manufactured by polishing a shaft portion using a sintered product of the MIM method.

  In Patent Document 1, since a forging process and a polishing process are required, it is sufficient to prepare a stainless steel plate material. However, in terms of time required for post-processing and effective use of the material, it is possible to improve production speed and cost during mass production. There is a limit to down. Moreover, when it becomes a complicated thin shape, it is difficult to produce a desired product shape by forging.

In Patent Document 2, a material made by lost wax or the MIM method is manufactured by pressing and a rolling process. However, a material processing method is not mentioned, and post-processing that occurs in the axial rolling process is inevitable. In addition, the accuracy is improved by uniaxial pressing from the top in the height direction. In particular, with the conventional MIM method, dimensional variations and deformations of more than ± 0.5% of the product dimensions occur during degreasing and sintering. Therefore, even if the dimensional accuracy is improved by pressing in the height direction, it is difficult to correct the deformation of the vane portion, and as a result, many places must be cut and polished.
Specifically, when the height of the wing portion is 10 mm, the dimensional variation of the product obtained by the conventional MIM manufacturing method occurs ± 0.05 mm. However, since deformation of about ± 0.05 mm occurs in the width direction of the wing, even if the height can be set to a desired size by pressing, when pressed in the width direction (thickness direction) of the wing Therefore, the shape of the blade portion having the calculated height and width cannot be obtained unless the sintered product has excellent dimensional accuracy not only in the height direction but also in the width direction. Also, in the coaxiality of the wing part and the shaft, the variation of the coaxiality in the conventional MIM sintered product occurs about ± 0.05 mm, so the dimensional accuracy of the shaft is kept within the dimensions by machining and pressing. However, in order to keep the coaxiality within 0.01 mm, machining of the wings is inevitable.

Similarly, Patent Document 3 does not mention a processing method by the MIM method, and polishing processing is unavoidable in order to improve the accuracy of the perpendicularity between the shaft portion and the polishing vane portion. In addition, it is difficult to obtain a highly accurate product only by the pressing method when twisting warpage occurs in the wing portion.
Japanese Patent No. 3833002 Japanese Patent No. 3944819 JP 2008-88849 A

  Therefore, in order to solve the above problem, an object of the present invention is to provide a method capable of manufacturing a variable vane with high dimensional accuracy only by a pressing method without performing a cutting process.

  As a result of intensive studies to solve the above problems, the present inventor prepared a sintered product having a shape approximate to the final product, and having a certain relationship with the desired final product. In the first press process of sintered products, the height and thickness direction (width direction) of the wings are set to the desired product dimensions at the same time. In the second press process, the concentricity between the wings and the shaft is desired. In the third step of pressing, the roundness of the shaft is set to the desired product size, so that the desired dimensional accuracy (target size ± 0.01 mm) can be obtained without cutting. The above-mentioned problems have been solved by succeeding in being within a range of 0.05 mm or less.

That is, the present invention is a method of manufacturing a variable vane having a flat wing portion and a cylindrical shaft portion located below the wing portion,
Pressing a sintered product having a shape close to the desired final product,
The sintered product is an integrally formed product of a blade portion and a shaft portion, and the height of the blade portion is + 0.3% to + 0.9% and the thickness of the blade portion is −− with respect to the target dimension of the final product. 0.6% to -0.0%, shaft diameter is + 0.3% to + 0.9%, length from lower end of wing to lower end of shaft is -0.6% to -0.0% %, And the sintered density is 95% or more, and the pressing step includes a three-stage process,
In the first pressing step, the sintered product is pressed by a lower die having a shaft portion insertion hole and an upper die having a shape other than the lower end surface of the wing portion, and the height and thickness of the wing portion are adjusted,
In the second pressing step, the blade portion and the shaft portion of the sintered product are simultaneously pressed by an upper die and a lower die each having a shape obtained by dividing the variable vane on a surface that divides the thickness of the blade portion into two. Adjusting the angle of the shaft portion with respect to the wing portion and the coaxiality of the shaft portion;
In the third press step, the upper die and the lower die each having the shape of a semi-cylindrical body corresponding to the shaft portion of the variable vane, the shaft portion of the sintered product from a direction 90 degrees different from the second press step. The roundness of the shaft portion is adjusted by pressing.

The mold used in the first press step is a lower mold for holding a sintered product by inserting a shaft part below the wing part, and an upper mold having a shape other than the lower end surface of the wing part (that is, the wing part) The shape in the height direction and the thickness direction can be defined simultaneously). In addition, when manufacturing the variable vane in which the shaft part also exists on the upper side of the wing part, the upper mold is a mold including the shape of the shaft part above the wing part in addition to the shape of the wing part. By pressing the upper mold toward the lower mold, while the wing is compressed downward, the upper surface of the wing is compressed and the side surface swells and deforms, and the side surface follows the mold shape, The desired wing height and sides and wing shape and axial squareness to the wing are achieved.
The mold used in the second press process consists of an upper mold and a lower mold each having a shape in which variable vanes (wing section and shaft section) are divided on a plane that divides the thickness of the wing section into two parts. By fixing the lower mold in the direction, compressing the upper mold downward, and simultaneously pressing the wing part and the shaft part, the perpendicularity of the shaft part with respect to the wing part and the coaxiality of the shaft part with respect to the wing part are obtained.
Furthermore, the mold used in the third press step is composed of an upper mold and a lower mold each having a semi-cylindrical shape corresponding to the shaft portion of the variable vane, and the shaft portion positioned below the blade portion of the sintered product is provided. The roundness of the shaft portion is obtained by pressing up and down while rotating 90 degrees from the second press step.

  When performing the above-mentioned press working, there is no cutting work by using a sintered product in which each dimension of the blade part and the shaft part is within the above-mentioned dimension range as a sintered product to be pressed with respect to the desired final product size. Thus, each dimension of the shaft part and the wing part can be accommodated to a desired dimensional accuracy (target dimension ± 0.01 to 0.05 mm or less). Further, by using a sintered product having a relative density of 95% or more, it is possible to produce a variable vane having a mechanical strength that can withstand high-temperature use and can keep the dimensional accuracy after pressing to a desired dimensional accuracy. it can.

  The sintered product is more preferably a sintered product having a relative density of 98% or more. Further, if a multi-forming machine capable of press bending from the 360 degree direction is used, the first press process to the third press process can be performed continuously, and the press process can be saved.

In order to produce a sintered product used in the pressing process,
After adding an organic binder (b) to the metal powder (a) and heating and mixing, an injection molding material is obtained by pulverization or pelletization, and the molding material is produced by injection molding the molding material. In the method having the step of heat degreasing,
Using a metal powder having an average particle diameter of 1 to 20 μm and a tap density of 3.5 g / m ³ or more as the metal powder (a),
Using an organic binder containing 5-40 Vol% polyacetal (b1) and 5-40 Vol% polypropylene (b2) as the organic binder (b),
In the step of adding the organic binder (b) to the metal powder (a), adding (b) to 30 to 60 Vol% with respect to (a + b),
Thus, a sintered product suitable for manufacturing the variable vane can be obtained.

In the manufacturing process of the sintered product,
The degreasing step is performed at a maximum temperature of 800 ° C. or less in any one of a reduced pressure inert gas atmosphere, an atmospheric pressure inert gas atmosphere and an atmospheric pressure hydrogen atmosphere, and the sintering step is performed under a reduced pressure inert gas atmosphere and a pressurized inert gas. It is preferably performed at 1000 ° C. or higher and 1500 ° C. or lower in any of an atmosphere, an atmospheric pressure inert gas atmosphere, and an atmospheric pressure hydrogen atmosphere.

  Furthermore, in the manufacturing process of the sintered product, after producing a primary sintered product having a relative density of 94% or more, the relative density is preferably made 98% or more by a hot isostatic pressing method.

According to the present invention, a variable vane with high dimensional accuracy can be manufactured only by pressing a sintered product without performing machining.
Also, in the manufacture of sintered products, by adopting the particle size, tap density, binder amount, and binder component of the above metal powder, a sintered product for variable vane manufacturing with higher dimensional accuracy than conventional can be obtained by the MIM method. Can be manufactured.

As shown in FIG. 1, the variable vane used in the turbocharger has a blade portion (nozzle vane portion) that adjusts the flow rate of exhaust gas and a shaft portion (vane shaft portion) that rotatably supports the blade portion. The shaft portion is connected to at least one side (lower side) from the rotation center position near the center of the wing portion. The shaft portion has a cylindrical shape, the wing portion has a flat plate shape, and has a wedge shape that becomes thinner toward the tip. Further, in many cases, the wing portion is thin and asymmetrically curved in order to easily adjust the flow rate of the exhaust gas, so that the stability of incorporation and the stability during operation can be improved.
Further, in the shaft portion, it is preferable that the opposite end surface connected to the wing portion has a planar shape as a molding surface, and the boundary between the end surface and the peripheral wall surface of the shaft portion is a curved surface. . By doing so, there is no mechanically unnecessary part to be machined, and the strength is improved. Further, since the end portion of the shaft portion is a curved surface, the stability of incorporation and the stability of rotation can be improved.

  There are two types of product shapes: those with a flat wing upper surface (see FIG. 1A) and those with a rotating shaft on the upper surface (see FIG. 1B). A product manufacturing method is shown in FIG. 2 (manufacturing flowchart).

  In the production of variable vanes, it is necessary to first produce a sintered product having a shape that approximates the desired final product. Using a molding material obtained by adding an organic binder, a molded body is prepared by molding in advance with a mold in consideration of the shrinkage rate after sintering of the product.

The metal used in the variable vane has corrosion resistance and is made of a heat-resistant steel metal material. As preferred metal materials for producing sintered products, SUS310 and SCH21 (HK30) in which the contents of Ni and Cr are Ni: 19.0 to 22.0 wt% and Cr: 23.0 to 27.0 wt%, respectively. Is mainly used. In addition, Inconel, which is a Ni-based alloy, is used.
As a metal powder made of such a metal material, an alloy powder produced by a water atomization or gas atomization method is usually used. In addition to the alloy powder produced by the atomization method, the alloy powder is adjusted to be an alloy component during sintering. Element powders may be added according to the composition. In general, water atomized powder can be produced in a larger amount than gas atomized powder, so the manufacturing cost is also low, but because the powder shape tends to be irregular, the tap density tends to be low, and The amount of oxygen also increases. On the other hand, although the manufacturing cost of the gas atomized powder is increased, it is easy to obtain a spherical powder and the tap density is increased. For this reason, the water atomized powder and the gas atomized powder may be mixed and used in consideration of the cost and the tap density.

  As for the average particle diameter of the metal powder (a) concerning this invention, 1-20 micrometers is preferable. When the average particle size is less than 1 μm, the amount of binder added increases as the surface area of the powder increases, and deformation during degreasing increases. In addition, when the amount of the binder is increased, the shrinkage rate at the time of sintering is increased, the dimensional variation after the sintering is increased, and it is difficult to obtain a product with high dimensional accuracy in the subsequent pressing process. When the powder particle diameter exceeds 20 μm, it becomes difficult to stably obtain a sintered density (relative density) of 95% or more, the strength is remarkably lowered, and it cannot be used as a product. A more preferable average particle diameter is 5 to 12 μm, and more desirably 8 to 10 μm. In the present invention, the average particle diameter means an average diameter of 50% cumulative weight measured using a particle size distribution measuring apparatus using a laser diffraction / scattering method. As such a particle size distribution measuring apparatus, a SALD-2000 model manufactured by Shimadzu Corporation can be used.

The metal powder (a) according to the present invention preferably has a tap density of 3.5 g / m ³ or more. When the tap density of the powder is less than 3.5 g / m ³ , it is necessary to increase the amount of the binder to be added by increasing the surface area of the powder, which causes dimensional variation during degreasing and sintering. The tap density is more preferably 4.0 g / m ³ or more, and still more preferably 4.2 g / m ³ or more. The upper limit is not particularly limited, but a sufficient effect can be obtained at a tap density of 5.0 g / m ³ or less.
The tap density can be measured by a measuring method described in “Metal Powder Tap Density Test Method” JPMA P 08 published by Japan Powder Metallurgy Industry Association.

As the organic binder (b), an organic binder containing 5 to 40 Vol% of polyacetal (b1) and 5 to 40 Vol% of polypropylene (b2) is used. By using polyacetal and polypropylene in the organic binder, the amount of deformation during degreasing can be suppressed as compared with conventional binders using polyethylene, ethylene vinyl acetate, and acrylic resin.
Polyacetal is indispensable as a substance that increases the strength of the molded body, prevents deformation of the molded body at 600 ° C. or lower during sintering, and does not leave carbides after sintering. Polypropylene imparts toughness to the shaped body and prevents cracking of the sintering and separation of the added low melting point compound. Polypropylene also has the property that no carbides remain after sintering.
When the addition amount of polyacetal and polypropylene is less than 5 Vol% with respect to the total amount (b) of the organic binder, deformation during degreasing becomes large, and the prescribed dimensional accuracy after sintering cannot be obtained. On the other hand, when the addition amount of polyacetal and polypropylene exceeds 40 Vol% with respect to the total amount (b) of the organic binder, the viscosity at the time of molding increases and the molding material cannot be completely filled in the mold.
A more preferable polyacetal content is 10 to 30% by volume, and a more preferable polypropylene content is 10 to 30% by volume.

As materials other than polyacetal and polypropylene, the following organic materials can be used.
Fatty acid ester, fatty acid amide, phthalic acid ester, paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, carnauba wax, montan wax, urethanized wax, maleic anhydride to provide fluidity and improve degreasing Modified waxes and polyglycol compounds are used. Particularly preferred materials include paraffin wax, fatty acid ester, and polypropylene wax.

  In addition, polyethylene, amorphous polyolefin, ethylene vinyl acetate copolymer, acrylic resin, polyvinyl butyral resin, glycidyl methacrylate resin, and the like can be used to impart fluidity during molding and flexibility in the molded body. Particularly preferred materials include polyethylene and amorphous polyolefin.

In order to improve the fluidity and degreasing properties, the organic binder is added to the total amount (a + b) of the metal powder (a) and the organic binder (b) in order to provide the fluidity and flexibility. (B) is preferably 30 to 60% by volume (Vol%), more preferably 35 to 50% by volume.
The organic binder and metal powder having the above ratio are heated and kneaded at about 160 to 180 ° C. for about 2 hours to completely disperse and mix the metal powder with the organic binder. Then, it is taken out and formed into a pellet having a diameter of about 5 mm by an extruder or a pulverizer, and used as a molding material.

For sintered products, considering the dimensional change due to pressing, the wing part has a desired dimension as the final product in the height direction and + 0.3% to + 0.9% of the desired dimension as the final product. The shaft is in the range of −0.6% to −0.0%, and the shaft portion has a diameter of + 0.3% to + 0.9% of a desired size as a final product, and a shaft below the wing portion. It is necessary to make the length of the part to be in the range of -0.6% to -0.0% of the desired dimension as the final product.
And in shaping | molding, it is necessary to determine a metal mold | die shape in consideration of the dimension after sintering. These dimensions are dimensions obtained after sintering or after hot isostatic pressing, and the dimensions differ depending on the sintering density. Therefore, the mold design needs to fully consider the subsequent dimensional changes. For this reason, it is necessary to design the dimensions of the mold in consideration of the dimensional accuracy, and it is necessary to calculate in advance the shrinkage rate from molding to sintering.

  In the conventional organic binder system, deformation occurs during the degreasing process, and it is very difficult to obtain a product within the size range of the sintered product, but the above-mentioned metal powder particle size, tap density, binder amount, binder component By doing so, a sintered product with higher dimensional accuracy than the conventional one can be manufactured by the MIM method.

As shown in FIG. 1, the thickness of the wing portion of the variable vane gradually decreases from the rear end side (left side in FIG. 1) to the front end side (right side in FIG. 1). The thickness varies depending on the measurement location. In the present invention, the thickness of the wing portion in the range of −0.6% to −0.0% with respect to the target dimension of the final product means that the final product and the sintered product (having a shape approximate to the final product). ) Means that the difference is within the above range.
If the height of the wing part, the diameter of the shaft part, and the length from the lower end of the wing part to the lower end of the shaft part also vary depending on the measurement location, the final product and sintered product as well as the thickness of the wing part Means that the difference is within the above range.

  Molds are mounted on an injection molding machine and molded, but the number of molded products obtained should be from 1 to 8 with a single mold, taking into account the size and mass production quantity of the product. Can do. The capacity of the injection molding machine is appropriately adjusted according to the number of molds to be taken and the size of the product. In general, molding is performed using a molding machine having a clamping force of about 20 to 100 tons. The injection speed and pressure are adjusted so that defects such as bubbles and cracks do not occur in the molded body, and the mold is provided with a gas escape to effectively release the air in the mold and the gas generated from the molding material. There is a need. If there is no effective gas escape, air or gas generated from the molding material is taken into the molded body, and bubbles are generated in the molded body.

  The obtained molded body is put into a degreasing furnace, and the added organic binder is removed. The degreasing furnace for removing the organic binder is performed using any one of a reduced pressure inert gas atmosphere, an atmospheric pressure inert gas atmosphere, and an atmospheric pressure hydrogen gas atmosphere. In the case of a sintering apparatus having a degreasing function, the degreasing sintering is performed. Can be done consistently. As the degreasing furnace, a batch type degreasing furnace or a continuous (belt type, pusher type, walking beam type) degreasing furnace can be used. In particular, it is effective to perform degreasing using a jig having a shape along the shape of the molded body so as to prevent deformation to a minimum in view of the fact that the amount of deformation increases during degreasing.

The degreasing atmosphere is performed at any one of a reduced pressure inert gas atmosphere, an atmospheric pressure inert gas atmosphere, and an atmospheric pressure hydrogen atmosphere at a maximum temperature of 800 ° C. or less.
When the degreasing atmosphere is in the air, the powder is oxidized at 300 ° C. or higher, and the amount of oxygen after sintering increases, which greatly affects the strength of the sintered product. Therefore, a depressurized inert gas atmosphere, an atmospheric pressure inert gas atmosphere, and an atmospheric pressure hydrogen atmosphere are used as the degreasing atmosphere. Nitrogen or argon is used as the inert gas, but it is desirable to use nitrogen gas in consideration of cost. In addition, the temperature rising rate during degreasing is preferably 50 ° C./hr from room temperature to 400 ° C. in consideration of deformation during degreasing. Moreover, the deformation | transformation at the time of degreasing of a molded object can be suppressed by using the jig | tool which considered the deformation | transformation of a molded object at the time of degreasing.
The degreasing temperature is 800 ° C. or lower. However, when the temperature is about 300 ° C., the organic binder tends to remain about 30%, and when the temperature is 600 ° C. or higher, the organic binder is easily removed completely. There exists a possibility that it may collapse | crumble, and a more preferable degreasing temperature is 400 to 500 degreeC at maximum. Moreover, it is effective to use a sintering furnace having a degreasing function as a method for preventing the collapse of these molded products, and it is possible to shift to sintering without lowering the temperature even after the degreasing. In addition, by connecting a continuous (belt, pusher, walking beam) sintering furnace as well as a continuous (belt, pusher, walking beam) degreasing furnace, sintering is not interrupted by degreasing. Processing can be performed continuously.

  In the sintering process, any one of a reduced pressure inert gas atmosphere, an atmospheric pressure inert gas atmosphere, a pressurized inert gas atmosphere, and an atmospheric pressure hydrogen atmosphere is used as the sintering atmosphere. As the inert gas, a stainless material is often used as a material during sintering. Therefore, it is preferable to use argon gas in consideration of nitriding of the material. The sintering temperature is 1000 ° C. or higher and 1500 ° C. or lower. However, if the sintering temperature is lower than 1000 ° C., the sintering is insufficient. In order for the sintered density to be 95% or more, 1200 to 1400 ° C is desirable, and further 1250 to 1380 ° C is desirable. In addition, it is desirable to maintain the maximum temperature for about 2 to 4 hours in consideration of improvement of the sintering density during sintering and dimensional variation during sintering. As in the degreasing process, deformation occurs at high temperatures in the sintering process, so it is effective to use a jig for preventing deformation of the sintered product.

  In degreasing and sintering, considering the production volume, batch type degreasing furnaces and sintering furnaces are used for small quantities of various products, and degreasing and sintering are performed by pusher type continuous furnaces and walking when the number increases. By using a continuous process using a beam-type continuous furnace and a belt-type continuous furnace, production can be dramatically improved.

By setting the density of the sintered product to 95% or more in terms of relative density, the mechanical strength and hardness at high temperatures can be maintained. If the relative density is less than 95%, the mechanical strength at high temperatures, particularly the elongation and hardness, are lowered, and continuous use at high temperatures is difficult.
The relative density of the sintered product can be measured by the Archimedes method.

  The obtained sintered product is further subjected to a hot isostatic pressing method (HIP method) in order to further increase the sintered density to improve the mechanical strength and to improve the reliability of the mechanical strength in a high temperature range. It is effective to be treated at a low temperature of about 10 ° C. to 100 ° C. lower than the sintering temperature and at a high pressure of about 10 MPa to 180 MPa, so that there is no pinhole inside and a relative density of 98% or more. A sintered product can be obtained stably. In addition, by using a sintered HIP apparatus that can perform a pressure treatment of up to about 6 MPa during the sintering process, a sintered product having a relative density of 98% or more can be obtained without using the HIP method in the subsequent process.

The sintered product after sintering or after the HIP process is formed into a desired final product size by the pressing process shown in FIGS.
In the first press step, the height and width (thickness) direction of the wing are simultaneously set to the desired product dimensions, and in the second press step, the concentricity between the wing and the shaft is set to the desired product dimensions. By setting the roundness of the shaft to a desired product dimension in the process, the dimensions of the shaft portion and the wing portion can be processed into a desired shape without cutting.
Hereafter, each press process is demonstrated in detail.

Press first process (dimension adjustment of wings)
In the first press process, the mold consists of a lower mold that holds the sintered product and an upper mold that simultaneously defines the height direction and width direction of the wings. By pressing the upper mold toward the lower mold, While the wing is compressed downward, the upper surface of the wing is compressed and the side surface swells and deforms, and the side surface follows the mold shape, so that the desired wing height and side and wing shape As well as the perpendicularity of the axis with respect to the wing.

Second press step (Adjustment of coaxiality between blade and shaft)
In the second press process, the mold consists of an upper mold and a lower mold each having a shape obtained by dividing the wing part and the shaft part of the variable vane into two parts (dividing the wing part thickness into two parts) and sintering. The product is fixed in the horizontal direction with the lower die, and the upper die is pressed toward the lower side to compress the wing and shaft at the same time, so that the axis is perpendicular to the wing and the axis is coaxial with the wing. Get.

Press third process (Adjusting the roundness of the shaft)
In the third press step, the mold is composed of an upper die and a lower die each having a shape (semi-columnar shape) obtained by dividing the shaft portion below the wing portion into two in the axial direction. The roundness of the shaft is obtained by rotating the shaft 90 degrees and pressing up and down.

  By subjecting the above-described sintered product to post-processing in these three-stage pressing processes, a desired variable vane can be obtained without performing cutting. Die steel, high-speed steel, and cemented carbide are used as the die material used for the press in consideration of the life. The press process uses a parts feeder and a progressive feed device to save labor, so that the processing capacity per hour can be greatly improved compared to conventional machining, and the processing capacity per hour is 300 to 600. It can be increased to about one.

  In order to further save labor in the press process, it is possible to save labor in the process by using a multi-forming machine capable of press bending from the 360-degree direction in the press process. A processing capacity of about 10 to 50 per hour can be dramatically improved to about 500 to 1000 per hour.

  Furthermore, the surface roughness of the product after pressing can be improved by barrel polishing and electrolytic polishing as needed, and burrs can be removed.

  According to the present invention, by using a sintered product obtained by the MIM process, in which the dimensional accuracy is controlled in advance, as a raw material, the post-processing does not perform a cutting process and a polishing process by machining, and the desired dimensional accuracy is excellent. A variable vane having a shape to be manufactured can be manufactured. In the present invention, particularly by adopting the MIM method, the production loss of the material can be suppressed to 5% or less even when compared with the conventional punching process of lost wax and plate material. By the automation process, the production efficiency is 5 to 10 times or more compared with the conventional manufacturing method by machining. In addition, by adopting the MIM method, it becomes possible to mass-produce variable vanes having a thinner and more complex shape, which was difficult to obtain easily in the past.

A sintered product according to the present invention was produced. The molding material, heat-kneading conditions, injection molding conditions, degreasing conditions, sintering conditions, etc. were as follows. 100 compacts were molded, degreased and sintered, and dimensional variations were measured.
・ Metal powder: SUS310 Average particle size 9.2μm Tap density 4.2g / m ³
・ Organic binder composition: Polyacetal 15Vol%, Polypropylene 25Vol%, Amorphous polyolefin 10Vol%, Paraffin wax 35Vol%, Acrylic resin 10Vol%, Fatty acid ester 5Vol%
・ Metal powder: 60Vol% Organic binder 40Vol%
・ Heat kneading: 180 ℃ for 2 hours ・ Injection molding conditions: 180 ℃ Mold temperature: 40 ℃
Degreasing conditions: Maximum temperature 500 ° C (nitrogen) held for 2 hours Total time 24 hours Sintering conditions: Maximum temperature 1350 ° C (argon, reduced pressure atmosphere) held for 2 hours

One mold for injection molding was taken, and the shape of the variable vane shown in FIG. 3A was adopted. The desired final product dimensions are as follows: A1 is the height of the wing, B1 is the thickness of the wing, C1 is the diameter of the shaft, D1 is the length of the shaft located below the wing (length from the lower end of the wing to the lower end of the shaft) Indicates.
Desired final product dimension A1: 6.0mm (target dimension) ± 0.01mm (5.99mm-6.01mm)
B1: 2.5mm (target dimension) ± 0.03mm (2.47mm to 2.53mm)
C1: 4.0mm (target dimension) ± 0.01mm (3.99mm to 4.01mm)
D1: 10.0mm (target dimension) ± 0.05mm (9.95mm to 10.05m)
Concentricity of shaft and wings: within 0.03mm, perpendicularity: within 0.03mm Parallelism of wings: within 0.03mm

The molding machine used was a molding machine with a clamping pressure of 30 tons. The dimensions of the manufactured sintered product were as follows. The dimension measurement was performed using a tool microscope.
Dimension A1: 6.024mm to 6.044mm (target dimension + 0.4% to + 0.73%)
B1: 2.485mm to 2.494mm (target dimension -0.60% to -0.24%)
C1: 4.018mm to 4.030mm (target size + 0.45% to + 0.75%)
D1: 9.955mm-9.980mm (target dimension -0.45%--0.2%)
Concentricity of shaft and wing: 0.035mm, perpendicularity: 0.042mm Parallelism of wing: 0.038mm
Sintered product density: 96.0%

A pressing process was performed by the process shown in FIG. The dimensions after the pressing process were as follows.
Dimensions of manufactured final product A1: 5.994mm ~ 6.003mm B1: 2.489mm ~ 2.515mm C1: 3.996mm ~ 4.004mm D1: 9.984mm ~ 0.029mm
Concentricity of shaft and wings: 0.017mm, perpendicularity: 0.009mm Parallelism of wings: 0.015mm

  Although the final product size could not be obtained after sintering, the product within the final product size tolerance could be obtained in the pressing process.

A sintered product according to the present invention was produced. The molding material, heat-kneading conditions, injection molding conditions, degreasing conditions, sintering conditions, etc. were as follows. 100 compacts were molded, degreased and sintered, and dimensional variations were measured.
・ Metal powder: HK30 Average particle size 8.7μm Tap density 4.3g / m ³
・ Organic binder composition: Polyacetal 20Vol%, Polypropylene 20Vol%, Amorphous polyolefin 10Vol%, Paraffin wax 35Vol%, Acrylic resin 10Vol%, Fatty acid ester 5Vol%
・ Metal powder: 60Vol% Organic binder 40Vol%
・ Heat kneading: 180 ℃ for 2 hours ・ Injection molding conditions: 180 ℃ Mold temperature: 40 ℃
・ Degreasing conditions: Maximum temperature 500 ° C (nitrogen) held for 2 hours Total time 24 hours ・ Sintering conditions: Maximum temperature 1350 ° C (argon, reduced pressure atmosphere) held for 2 hours ・ HIP treatment: Processing temperature 1200 ° C (argon, 100 MPa) 2 Time hold

One mold for injection molding was taken, and the shape of the variable vane shown in FIG. 3B was adopted. The desired final product dimensions are as follows: A2 is the height of the wing, B2 is the thickness of the wing, C2 is the diameter of the shaft, and D2 is the length of the shaft located below the wing.
Desired final product dimension A2: 6.0 mm (target dimension) ± 0.01 mm (5.99 mm to 6.01 mm)
B2: 2.5mm (target dimension) ± 0.03mm (2.47mm to 2.53mm)
C2: 4.0mm (target dimension) ± 0.01mm (3.99mm to 4.01mm)
D2: 10.0mm (target dimension) ± 0.05mm (9.95mm to 10.05m)
Concentricity of shaft and wings: within 0.05mm, perpendicularity: within 0.03mm Parallelism of wings: within 0.03mm

The molding machine used was a molding machine with a clamping pressure of 30 tons. The dimensions of the manufactured sintered product were as follows. The dimension measurement was performed using a tool microscope. C2a indicates the diameter of the shaft portion located below the wing portion, and C2b indicates the diameter of the shaft portion located above the wing portion.
Dimension A2 of the manufactured sintered product : 6.024mm to 6.049mm (target size + 0.4% to + 0.82%)
B2: 2.487mm to 2.494mm (target dimension -0.52% to -0.24%)
C2a: 4.016mm to 4.028mm (target size + 0.4% to + 0.7%)
C2b: 4.015mm to 4.031mm (target size + 0.38% to + 0.78%)
D2: 9.961mm-9.92mm (target dimension -0.39%--0.08%)
Concentricity of shaft and wings: 0.062mm, perpendicularity: 0.044mm Parallelism of wings 0.035mm
Sintered product density: 99.2%

A pressing process was performed by the process shown in FIG. The dimensions after the pressing process were as follows.
Dimensions A2: 5.993mm to 6.005mm B2: 2.479mm to 2.505mm C2a: 3.993mm to 4.003mm C2b: 3.996mm to 4.002mm D2: 9.982mm to 10.023mm
Concentricity of shaft and wing: 0.031mm, perpendicularity: 0.014mm Parallelism of wing: 0.016mm

  Although the final product size could not be obtained after sintering, the product within the final product size tolerance could be obtained in the pressing process.

[Comparative Example 1]
The following sintered bodies were produced under the same conditions as in Example 1.
Dimension of sintered product manufactured A1: 5.985mm ~ 6.005mm (Target size of final product -0.25% ~ + 0.08%)
B1: 2.490mm to 2.505mm (Target size of final product -0.4% to + 0.2%)
C1: 3.985mm to 4.006mm (Target size of final product -0.38% to + 0.15%)
D1: 9.985mm ~ 10.005mm (Target size of final product -0.15% ~ + 0.05%)
Coaxiality of shaft and wings: 0.040mm, perpendicularity 0.044mm Parallelism of wings 0.039mm
Sintered product density: 96.0%

Three-stage pressing was performed using the sintered body under the same conditions as in Example 1. The dimensions after the pressing process were as follows.
Dimensions of manufactured final product A1: 5.985mm ~ 6.003mm B1: 2.490mm ~ 2.515mm C1: 3.986mm ~ 4.003mm D1: 9.986mm ~ 10.09mm
Concentricity of shaft and wing: 0.032mm, perpendicularity: 0.036mm Parallelism of wing: 0.030mm

Although the product which made the sintered product size close to the final product size was created, a product within the dimensional tolerance of the final product could not be obtained for A1 and C1. Also, the coaxiality and verticality could not be within tolerance.
This is presumably because the difference between the sintered products A1 and C1 before the pressing step and the desired final product was large.

  Furthermore, in order to investigate the influence of the difference between the dimensions A to D of the sintered product and the target size of the final product on the tolerance of the final product, various sintered products were created under the same conditions as in Example 1. The relationship between the final product after pressing and the sintered product before pressing was examined. The results are shown in Table 1.

  From the results of Example 3, the sintered product before pressing had a blade height of + 0.3% to + 0.9% and a blade thickness of the desired final product dimensions (target dimensions). -0.6% to -0.0%, shaft diameter is + 0.3% to + 0.9%, and the length from the lower end of the wing portion to the lower end of the shaft portion is -0.6% to -0. It has been found that when it is in the range of 0% and the sintered density is 95% or higher, the final product with the desired dimensional tolerance can be obtained only by the pressing process.

[Comparative Example 2]
Of the organic binder components of Example 1, an attempt was made to produce a sintered product in the same manner as in Example 1 except that an organic binder in which polyacetal was replaced with ethylene vinyl acetate resin was used.
However, after degreasing, the molded body was not able to proceed to the subsequent sintering and pressing processes because the wing portion was tilted by 30 degrees or more as shown in FIG.

  Also, when an organic binder in which polypropylene is replaced with polyethylene is used, after degreasing, the molded body is inclined more than 10 degrees as shown in FIG. I couldn't.

In addition, as a result of creating molded bodies from various injection molding materials and attempting degreasing and sintering, metal powder having an average particle diameter of 1 to 20 μm and a tap density of 3.5 g / m ³ or more is used. In addition, an organic binder containing 5 to 40% by volume of polyacetal and 5 to 40% by volume of polypropylene was used, and the amount of the organic binder was set to 30 to 60% by volume with respect to the total amount of the metal powder and the organic binder. In some cases, it was found that a sintered product suitable for use in the pressing step according to the present invention was obtained.

A indicates a variable vane having a flat upper surface of the wing portion, and B indicates a variable vane having a shaft portion on the upper side of the wing portion. In each, (a) is a front view, (b) is a right side view, (c) is a bottom view, and (d) is a perspective view. It is a flowchart which shows one Example of the manufacturing method of the variable vane concerning this invention. A indicates a variable vane having a flat upper surface of the wing portion, and B indicates a variable vane having a shaft portion on the upper side of the wing portion. The process which presses the variable vane whose upper surface of a wing | blade part is flat in three steps is shown. The process of pressing the variable vane having the shaft portion on the upper side of the wing portion in three stages is shown. The state which the molded object of the comparative example 2 deform | transformed after degreasing is shown.

Explanation of symbols

1 variable vane 2 wing part 3 shaft part (shaft part located below the wing part)
3 'shaft (shaft located above the wing)

Claims (6)

A method of manufacturing a variable vane having a flat blade portion and a cylindrical shaft portion located below the blade portion,
Pressing a sintered product having a shape close to the desired final product,
The sintered product is an integrally formed product of a blade portion and a shaft portion, and the height of the blade portion is + 0.3% to + 0.9% and the thickness of the blade portion is −− with respect to the target dimension of the final product. 0.6% to -0.0%, shaft diameter is + 0.3% to + 0.9%, length from lower end of wing to lower end of shaft is -0.6% to -0.0% %, And the sintered density is 95% or more, and the pressing step includes a three-stage process,
In the first pressing step, the sintered product is pressed by a lower die having a shaft portion insertion hole and an upper die having a shape other than the lower end surface of the wing portion, and the height and thickness of the wing portion are adjusted,
In the second pressing step, the blade portion and the shaft portion of the sintered product are simultaneously pressed by an upper die and a lower die each having a shape obtained by dividing the variable vane on a surface that divides the thickness of the blade portion into two. Adjusting the angle of the shaft portion with respect to the wing portion and the coaxiality of the shaft portion;
In the third press step, the upper die and the lower die each having the shape of a semi-cylindrical body corresponding to the shaft portion of the variable vane, the shaft portion of the sintered product from a direction 90 degrees different from the second press step. A method for producing a variable vane, wherein the roundness of the shaft portion is adjusted by pressing.   The method for producing a variable vane according to claim 1, wherein the sintered product is a sintered product having a relative density of 98% or more.   The variable vane manufacturing method according to claim 1, wherein the first press process to the third press process are continuously performed using a multi-forming machine capable of press bending from a 360-degree direction. . Further, the method includes a step of manufacturing the sintered product, and after the sintered product manufacturing step adds and heat-mixes the organic binder (b) to the metal powder (a), an injection molding material is obtained by pulverization or pelletization. The molding material is injection-molded to produce a molded body, and the obtained molded body is heated and degreased,
The metal powder (a) is a powder having an average particle diameter of 1 to 20 μm and a tap density of 3.5 g / m ³ or more;
The organic binder (b) contains 5-40 Vol% polyacetal (b1) and 5-40 Vol% polypropylene (b2),
In the step of adding the organic binder (b) to the metal powder (a), the organic binder (b) is added so as to be 30 to 60 Vol% with respect to the total amount of the metal powder and the organic binder (a + b).
The manufacturing method of the variable vane of Claims 1-3 characterized by these. In the manufacturing process of the sintered product,
The degreasing step is performed at a maximum temperature of 800 ° C. or less in any one of a reduced pressure inert gas atmosphere, an atmospheric pressure inert gas atmosphere and an atmospheric pressure hydrogen atmosphere, and the sintering step is performed under a reduced pressure inert gas atmosphere and a pressurized inert gas. 5. The method for producing a variable vane according to claim 4, wherein the method is performed at 1000 ° C. or more and 1500 ° C. or less in any one of an atmosphere, an atmospheric inert gas atmosphere, and an atmospheric hydrogen atmosphere.   In the manufacturing process of the sintered product, after producing a primary sintered product having a relative density of 94% or more, a sintered product having a relative density of 98% or more is obtained by a hot isostatic pressing method. The method for producing a variable vane according to claim 4 or 5.

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