阅读说明：本技术 涡轮机壳体的制造方法 (Method for producing a turbine housing ) 是由 冈本宽之 横嶋悟 于 2018-12-21 设计创作，主要内容包括：在涡轮机壳体的制造方法中,涡轮机壳体的废气流路由金属板分割体和铸造分割体构成,对金属板材料进行冲压成形而形成金属板分割体,通过铸造来成形铸造分割体,在对铸造分割体进行铸造时,将金属板分割体的一端熔化而使其铸入到铸造分割体的内部,使该一端的原来的形状消失。(In a method for manufacturing a turbine casing, an exhaust gas flow path of the turbine casing is composed of a metal plate segment and a cast segment, the metal plate segment is formed by press molding a metal plate material, the cast segment is formed by casting, and when the cast segment is cast, one end of the metal plate segment is melted and cast into the cast segment, and the original shape of the one end is lost.)

1. A method of manufacturing a turbine housing whose exhaust gas flow path is constituted by a metal plate segment and a cast segment, characterized by comprising:

a step of forming the metal plate segment by press-forming a metal plate material; and the number of the first and second groups,

a casting step of molding the cast segment body,

in the casting step, one end of the divided metal plate is melted and cast into the cast divided body, and the original shape of the one end is removed.

2. The method of manufacturing a turbine housing of claim 1,

the casting process includes:

a wax molding step of molding wax into the shape of the cast segment and molding a wax master into which the one end of the metal plate segment is fitted;

a coating step of forming a coating layer on the surface of the wax master;

a cavity forming step of forming a cavity by removing the wax master; and

a molten metal step of injecting molten metal into the cavity while heating the cavity to a predetermined temperature to form the cast segment,

the predetermined temperature is set to a temperature at which the wax is melted or higher and at which the high-temperature oxidation resistance of the metal plate material is maintained.

3. The method of manufacturing a turbine housing according to claim 2,

in the cavity forming step, the wax master is heated at a temperature equal to or higher than the melting point of the wax and maintaining the high-temperature oxidation resistance of the metal plate material.

4. A method of manufacturing a turbine housing according to claim 3,

in the step of forming the metal plate segment, a bent portion is formed at the one end of the metal plate segment,

in the wax molding step, the bent portion is insert-molded into the wax master, and the metal plate split body is fixed to the wax master.

5. The method of manufacturing a turbine housing according to claim 3 or 4,

the wax pattern is formed so that an inner surface of the exhaust gas flow passage of the metal plate segment and an inner surface of the cast segment smoothly contact each other.

6. The method of manufacturing a turbine housing according to any one of claims 1 to 5,

in the casting step, an end portion of the exhaust pipe is melted and cast into the cast segment.

7. The method of manufacturing a turbine housing of claim 6,

the other end portion of the exhaust pipe is fixed to an exhaust outlet side flange by welding.

8. The method of manufacturing a turbine housing according to any one of claims 1 to 7,

the cast segment body is located opposite the turbine housing.

Technical Field

The present invention relates to a method of manufacturing a turbine housing used in a turbocharger (turbo super supercharger) of a vehicle.

Background

As a turbine housing of a turbocharger, a cast housing is generally used, and for example, a turbine housing proposed in patent document 1 is used. The turbine housing is manufactured by an investment casting method, and is lightweight and heat resistant.

Further, for example, patent document 2 proposes a turbine housing made of a metal plate, which is manufactured using a Press (Press) formed product of a steel plate for further reduction in weight. According to patent document 2, a base is formed at one end of a metal plate-made shell by casting. That is, one end of a metal plate-made shell is integrally joined to a base by casting.

(Prior art document)

(patent document)

Patent document 1: japanese patent laid-open publication No. 2003-56336

Patent document 2: japanese patent laid-open publication No. 2004-143937

Disclosure of Invention

(problems to be solved by the invention)

However, when the turbine housing is produced by the method of patent document 2, the shell may function as a chill (radiator) inside the mold, and the shell may remain without being completely melted in the molten metal. That is, only by fixing the casting material to the surface of the remaining shell, there is a possibility that a state of a boundary surface is formed between the shell and the casting material. Further, there is a possibility that a gap such as a crack may occur between the shell and the casting material. In such a joined state, the joining strength is insufficient, and there is a possibility of fatigue failure due to vibration or thermal stress in the use environment of the turbine housing.

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a method for manufacturing a turbine casing in which the joining strength is sufficiently ensured.

(measures taken to solve the problems)

In the method for manufacturing a turbine casing according to the present invention, the exhaust gas flow path of the turbine casing is composed of the metal plate segment and the cast segment, the metal plate segment is formed by press molding the metal plate material, the cast segment is formed by casting, and when the cast segment is cast, one end of the metal plate segment is melted and cast into the cast segment, and the original shape of the one end is lost.

(Effect of the invention)

According to the present invention, when a member made of a metal plate and a member made of a cast material are integrally joined, the joint strength can be sufficiently secured, and the possibility of fatigue failure due to vibration or thermal stress in the use environment of the turbine housing can be reduced.

Drawings

Fig. 1 is a side view of a turbine housing used in a turbocharger according to an embodiment of the present invention.

Fig. 2 is a front view of the turbine housing.

FIG. 3 is a rear view of the turbine housing described above.

Fig. 4 is a cross-sectional view of the turbine housing described above.

Fig. 5 is a sectional view taken along the line Y-Y in fig. 4.

Fig. 6 is a sectional view of a mold for precision casting a metal plate member and a metal plate exhaust pipe of the turbine housing.

Fig. 7 is a sectional view of a wax pattern insert-molded by the mold.

Fig. 8 is a sectional view of a wax pattern having a coating layer formed on a surface thereof.

Fig. 9 is a sectional view showing a state where a wax pattern is melted out to form a cavity.

Fig. 10 is a sectional view of a precision-cast molded article using the mold.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a side view of a turbine housing used in a turbocharger according to an embodiment of the present invention, fig. 2 is a front view of the turbine housing, fig. 3 is a rear view of the turbine housing, fig. 4 is a cross-sectional view of the turbine housing, fig. 5 is a cross-sectional view taken along the line Y-Y in fig. 4, fig. 6 is a cross-sectional view of a mold for precision casting a metal plate member of the turbine housing and an exhaust pipe made of a metal plate, fig. 7 is a cross-sectional view of a wax mold insert-molded by the mold, fig. 8 is a cross-sectional view of the wax mold having a coating layer formed on the surface, fig. 9 is a cross-sectional view of a state in which the wax mold is melted to form a cavity, and fig. 10 is a cross-sectional view of a molded.

As shown in fig. 1 to 4, the turbine housing 10 is used as a housing of a turbocharger (turbo super supercharger) of a vehicle. The turbine housing 10 has a double-shell (double-pipe) structure including an inner cylinder 20, an exhaust pipe 30 connected to a portion (cylindrical portion 23d) on the exhaust outlet side of the inner cylinder 20, and an outer cylinder 40 covering the inner cylinder 20 and the exhaust pipe 30 with a predetermined gap G therebetween, wherein the inner cylinder 20 forms an exhaust flow path K formed between a center flange 11, an exhaust inlet side flange 12, and an exhaust outlet side (downstream side of exhaust gas flow) flange 13; the central flange 11 is made of a casting; the exhaust gas inlet side flange 12 constitutes an inlet 12a of the exhaust gas B and is made of a casting; the exhaust-gas-outlet-side flange 13 constitutes an outlet 13a of the exhaust gas B. The turbine housing 10 discharges the exhaust gas B entering from the inlet 12a of the exhaust gas inlet-side flange 12 from the outlet 13a of the cast exhaust gas outlet-side flange 13 via the turbine wheel 14 disposed in the convoluted center portion (center portion) O of the inner tube 20.

As shown in fig. 1, a compressor 15 is connected to the center flange 11. Further, a catalytic converter (exhaust gas purification device) 16 for removing harmful pollutants in the exhaust gas B is connected to the exhaust outlet-side flange 13 for discharging the exhaust gas B via a connection flange 17 and a connection pipe 18. That is, the turbine housing 10 is interposed between the catalytic converter 16 and the suction-side compressor 15.

As shown in fig. 2 and 4, the inner cylinder 20 substantially defines an exhaust gas flow path K for exhaust gas B forming the inside of the casing, and the outer cylinder 40 is configured as a casing structure that completely covers the inner cylinder 20 and the exhaust pipe 30 with a predetermined gap G therebetween, and that protects the inner cylinder 20 and the exhaust pipe 30, insulates heat, and improves the rigidity of the turbine casing 10.

As shown in fig. 4, the inner cylinder 20 is composed of a first inner cylinder divided body 21 (a metal plate divided body), a second inner cylinder divided body 22 (a metal plate divided body), and a third inner cylinder divided body 23 (a cast divided body), the first inner cylinder divided body 21 and the second inner cylinder divided body 22 are composed of a thin plate-shaped member made of a metal plate divided into two parts in a direction orthogonal to the axial direction L of the turbine shaft 14a of the turbine wheel 14, and the third inner cylinder divided body 23 is composed of a precision cast member facing the turbine wheel 14 (a region on the exhaust gas outlet side of the exhaust gas B). Further, the third inner cylinder divided body 23 is formed by lost-wax casting using a casting material having a higher heat resistance than a metal plate. As a metal plate material constituting the first inner tube divided body 21 and the second inner tube divided body 22, for example, ferritic stainless steel SUS429 or SUS430 can be used. As the casting material, the same kind of material as the metal plate material is used. In the present embodiment, ferritic stainless steel corresponding to a metal plate material is used.

As shown in fig. 2 and 4, the first inner tube segment 21 and the second inner tube segment 22 are formed into a predetermined bent cylindrical shape by press working of a metal plate, and the end 21b on the rear peripheral side of the first inner tube segment 21 and the end 22a on the front peripheral side of the second inner tube segment 22, which are formed of the two press-formed metal plates, are welded and joined and fixed. That is, the rear peripheral side end portion 21b of the first inner tube segment 21 and the front peripheral side end portion 22a of the second inner tube segment 22 are bent perpendicularly outward and have different lengths, and the end portions 21b and 21a having different lengths are fixed by welding (the welded portion is denoted by symbol E).

Further, as shown in fig. 2 and 4, the third inner tube segment 23 is formed into a predetermined curved cylindrical shape by precision casting, and as shown in fig. 4, a portion on the rear peripheral side end portion 22b side of the second inner tube segment 22 made of a metal plate and a portion on the rear peripheral side stepped concave end portion 23b side of the third inner tube segment 23 made of a precision casting are joined to each other by casting a portion on the rear peripheral side end portion 22b side of the second inner tube segment 22 made of a metal plate together into the third inner tube segment 23 in the precision casting process of the third inner tube segment 23. In fig. 4, the end portion 22b which is cast in the third inner tube segment 23 is shown by a broken line, but this is merely for convenience of explanation to show the shape of the metal plate of the end portion 22b before casting. Actually, when the third inner tube segment 23 is cast, the end portion 22b is melted (melted so that the original shape of the end portion 22b disappears) and cast into the third inner tube segment 23, so that the second inner tube segment 22 and the third inner tube segment 23 are integrated. Thus, a portion of the inner cylinder 20 facing the turbine wheel 14 on the exhaust gas outlet side of the exhaust gas B is formed by the precision-cast third inner cylinder segment 23, and the remaining portions are formed by the first and second inner cylinder segments 21 and 22 made of a metal plate, and the exhaust gas flow passage K is formed inside thereof, wherein the precision-cast third inner cylinder segment 23 is formed by a precision-cast member, and the first and second inner cylinder segments 21 and 22 made of a metal plate are formed by a plate material made of a metal plate.

As shown in fig. 2 and 4, the front surface 23a of the third inner tube segment 23 made of precision casting is a flat portion, and is formed such that the area of the lower side (the exhaust gas inlet side flange 12) is larger than the area of the upper side (the opposite side of the exhaust gas inlet side flange 12). That is, as shown in fig. 4, the portion of the third inner tube segment 23 made of precision casting near the exhaust inlet side flange 12 is formed to have a larger wall thickness than the portion on the opposite side. Thus, the third inner tube segment 23 made of precision casting forms a part of the flow path surface K of the exhaust gas flow path K of the inner tube 20.

Further, a stepped annular recess 23c is formed on the exhaust gas inlet side of the third inner tube segment 23 made of precision casting, and a cylindrical portion 23d (cylindrical portion) is integrally formed on the exhaust gas outlet side in a protruding manner. An annular reinforcing member (not shown) for protecting the turbine wheel 14 is fitted into the stepped annular recess 23 c.

As shown in fig. 4, the inner wall of the cylindrical portion 23d of the third inner tube segment 23 made of precision casting is formed as a substantially conical inclined surface 23e expanding toward the outlet side. Between the portion on the inclined surface 23e side inside the cylindrical portion 23d of the third inner cylindrical divided body 23 and the portion on the front end portion 31 side of the metal plate cylindrical exhaust pipe 30, the portion on the front end portion 31 side of the exhaust pipe 30 is cast together with the portion on the inclined surface 23e side of the inner wall of the cylindrical portion 23d of the third inner cylindrical divided body 23 in the precision casting process of the third inner cylindrical divided body 23, whereby the metal plate exhaust pipe 30 is joined to the precision cast third inner cylindrical divided body 23. In fig. 4, the end 31 which is cast into the third inner tube segment 23 is shown by a broken line, but this is merely for convenience of explanation to show the shape of the metal plate of the end 31 before casting. Actually, when the third inner tube segment 23 is cast, the end portion 31 is melted (melted so that the original shape of the end portion 31 disappears) and cast into the third inner tube segment 23, and the exhaust pipe 30 and the third inner tube segment 23 are integrated.

As shown in fig. 1 to 4, the outer cylinder 40 is formed of two thin plate members made of metal plate, i.e., a first outer cylinder divided body 41 and a second outer cylinder divided body 42, which are divided into two parts in the axial direction L (vibration direction during vehicle traveling) of the turbine shaft 14a of the turbine wheel 14. The first outer tube divided body 41 and the second outer tube divided body 42 are formed in a predetermined bent shape by press working a metal plate, and the first outer tube divided body 41 made of two metal plates formed by press working and the second outer tube divided body 42 made of a metal plate are welded and joined to each other, thereby completely covering the inner tube 20 and the exhaust pipe 30 with a predetermined gap G therebetween.

That is, as shown in fig. 1, 3, and 4, the other end portion 41b of the first outer tube divided body 41 made of a metal plate extending in a stepped manner and the one end portion 42a of the second outer tube divided body 42 made of a metal plate extending in a stepped manner are overlapped so that the other end portion 41b of the first outer tube divided body 41 is positioned downward, and are welded (a welded portion is indicated by a symbol E) along an axial direction L (a linear direction of the shaft) of the turbine shaft 14a of the turbine wheel 14 to be fixed to each other. Accordingly, since the turbine shaft 14a contracts in the axial direction L during vehicle running, the weld can be prevented from being broken by fusion welding in the axial direction L.

As shown in fig. 5, the respective plates 45 and 46 (reinforcing plate material) made of a metal plate press-formed along the curved shape of the outer cylinder 40 are fixed to the inner surfaces of the first outer cylinder divided body 41 made of a metal plate and the second outer cylinder divided body 42 made of a metal plate constituting the outer cylinder 40 by at least one welding.

As shown in fig. 2 and 4, the center flange 11 is formed in an annular shape, and a bearing, not shown, of a turbine shaft 14a of the turbine wheel 14 is disposed in a central circular opening 11a thereof. In the precision casting process of the center flange 11, the first inner tube segment 21 made of a metal plate is joined to the portion on the inner peripheral surface 11b side of the center flange 11 by casting the portion on the front peripheral edge side end portion 21a side of the first inner tube segment 21 made of a metal plate together with the portion on the inner peripheral surface 11b side of the center flange 11. In fig. 4, the end portion 21a which is cast into the center flange 11 is shown by a broken line, but this is merely for convenience of explanation to show the shape of the metal plate of the end portion 21a before casting. Actually, when the center flange 11 is cast, the end portion 21a is melted (melted so that the original shape of the end portion 21a disappears) and cast into the center flange 11, so that the first inner tube segment 21 and the center flange 11 are integrated.

Further, the outer peripheral surface 11c of the center flange 11 is fixed by welding (a welded portion is denoted by symbol E) to the respective end portions 41c, 42c on the front peripheral edge side of the first outer cylinder divided body 41 made of a metal plate and the second outer cylinder divided body 42 made of a metal plate constituting the outer cylinder 40. A plurality of screw holes 11d for mounting bolts are formed at equal intervals in the center flange 11.

As shown in fig. 4, the exhaust outlet flange 12 is formed in a substantially annular shape, and an opening portion 12a thereof serves as an inlet of the exhaust gas B. A stepped annular recess 12c is formed on the inner side of the upper side of the outer peripheral surface 12b of the exhaust inlet side flange 12, and a stepped portion 12e protruding inward is integrally formed on the middle portion of the inner peripheral surface 12d of the exhaust inlet side flange 12. The lower end portion 21c side of the first metal plate inner tube segment 21 and the lower end portion 22c side of the second metal plate inner tube segment 22 of the inner tube 20 are each formed in a semicircular arc curved shape along the upper portion of the step portion 12e, and are fitted with the step portion 12e with an opening 25 (gap) therebetween so as to be freely extendable and retractable.

As shown in fig. 2 to 4, the lower end portions 41E and 42E of the first and second metal plate outer cylinder segments 41 and 42 constituting the outer cylinder 40 are formed in a semicircular arc curved shape along the concave portion 12c of the exhaust inlet flange 12, respectively, and are fixed to the upper side of the outer peripheral surface 12b by welding (the welded portion is denoted by symbol E) in a state of being fitted in the concave portion 12 c. Further, a plurality of screw holes for mounting bolts, not shown, are formed at equal intervals in the exhaust gas inlet-side flange 12.

Further, as shown in fig. 3 and 4, the exhaust outlet side flange 13 is formed in a substantially rectangular plate shape, and a central circular opening 13a thereof serves as an outlet of the exhaust gas B. The rear peripheral side end portions 41d and 42d of the first and second metal plate outer cylinder segments 41 and 42 constituting the outer cylinder 40 and the rear side end portion 32 of the exhaust pipe 30 are fixed to the inner peripheral surface 13b of the exhaust outlet side flange 13 by welding (the welded portion is denoted by symbol E). Further, screw holes 13d for bolt attachment are formed in the corners of the exhaust outlet side flange 13.

The second inner cylindrical divided body 22 made of a metal plate of the turbine housing 10 of the above embodiment, and the third inner cylindrical divided body 23 made of a casting and the exhaust pipe 30 made of a metal plate forming the region on the exhaust outlet side of the exhaust gas B are manufactured by an investment (lost wax) precision casting method using a mold 50 composed of a pair of lower dies 51, 52 and an upper die 53 shown in fig. 6.

Specifically, as shown in fig. 6, first, in the step of pressing the second divided body 22 made of a metal plate, the bent portions 22b are press-formed in advance in the portions fitted into the wax 56, and the passage inner surface (gas flow passage surface) side of the second inner tube divided body 22 made of a metal plate is press-formed in advance as a surface 22d which smoothly comes into contact with the third inner tube divided body 23 made of a casting without a step.

A dewaxing mold core 54 (e.g., a ceramic mold core) integrated with the exhaust pipe 30 in advance is sandwiched between the pair of lower molds 51 and 52 to form a lower mold.

Next, the second inner tube divided body 22 made of a metal plate which is press-formed in advance is set on the pair of lower dies 51, 52, and then the upper die 53 is closed with the pair of lower dies 51, 52. From this state, wax 56 is injected into the cavity 55 of the mold 50 to form a wax pattern 57 (wax master) into which the exhaust pipe 30 and the second inner cylinder segment 22 are fitted. As shown in fig. 7, the completed wax pattern 57 is in a state where the dewaxing mold core 54 is inserted into the exhaust pipe 30.

Next, a mold 50 is produced.

First, a gate is provided on the wax pattern 57, and as shown in fig. 8, the surface of the wax pattern 57 is ceramic-coated (multi-layered) to form a coating 81 (ceramic coating). Subsequently, heating/dewaxing was performed. That is, the ceramic-coated wax mold 57 is heated to melt out the wax 56 from the gate to the outside of the mold, and as shown in fig. 9, a cavity is formed in a portion where the wax 56 exists. Then, the mold 50 is completed by firing.

In the step (heating/dewaxing step) of heating the ceramic-coated wax pattern 57 to melt out the wax 56 from the gate to the outside of the mold, the wax pattern 57 is heated at a temperature not lower than the melting point of the wax. At this time, in order to prevent abnormal oxidation of the metal plate during the heating/dewaxing step, the upper limit temperature of heating of the wax pattern 57 in the heating/dewaxing step is set to a high temperature oxidation resistant temperature (temperature capable of resisting abnormal oxidation) of the material constituting the metal plate. For example, in the heating/dewaxing process, the wax pattern 57 is heated in a range of 700 ℃ to 1300 ℃. When SUS430 is used as the metal plate material, the wax pattern 57 is heated at a temperature of about 700 to 900 ℃ in accordance with the high-temperature oxidation resistance temperature of SUS of about 900 ℃.

If an oxide film is formed on the surface of the metal plate, the oxide film interferes with the melting of the metal plate in a casting step described later. Therefore, in the heating/dewaxing step, the temperature at the time of heating the wax pattern 57 is controlled so as to suppress the formation of an oxide film on the surface of the metal plate.

Next, the molten metal is poured from the gate into the cavity 55 of the mold 50 from which the wax 56 has been melted, and after the molten metal has cooled, the mold is removed, and the mold 50, the core 54, and the gate are removed, and then deburring is performed, thereby completing the final processing. Thereby, the molded article 58 shown in fig. 10 is completed, and the cast-in portion of the metal plate portion 58A and the cast portion 58B in the exhaust pipe 30 and the second inner tube divided body 22 are completely melted. That is, one end of the metal plate portion 58A is melted and cast into the casting portion 58B, and the original shape of the one end is lost. In fig. 10, when the third inner tube segment 23 is cast, the end portion 22b is melted and cast into the third inner tube segment 23, and the end portion 22b is eliminated, so that the second inner tube segment 22 and the third inner tube segment 23 are integrated. In fig. 10, when the third inner tube segment 23 is cast, the end portion 31 is melted and cast into the third inner tube segment 23, and the end portion 31 is removed, so that the exhaust pipe 30 and the third inner tube segment 23 are integrated. In the same manner as in the integrated state shown in fig. 10, when the center flange 11 is cast, the end portion 21a is melted and cast into the center flange 11, and the end portion 21a is eliminated, so that the first inner tube segment 21 and the center flange 11 are integrated.

In the step (casting step) of pouring the molten metal from the gate into the cavity 55 of the mold 50 after the wax 56 is melted, the wax mold 57 is heated at a temperature between the lower limit temperature and the upper limit temperature, with the melting point temperature of the wax being the lower limit temperature and the high-temperature oxidation resistance temperature of the material constituting the metal plate being the upper limit temperature. For example, in the casting process, the wax pattern 57 is heated in a range of 700 ℃ to 1300 ℃. When SUS430 is used as the metal plate material, the wax pattern 57 is heated at a temperature of about 700 to 900 ℃ in response to the high-temperature oxidation resistance of SUS of about 900 ℃. Here, since the molten metal is molded while keeping the temperature of the cavity at a temperature close to the solidification point of the molten metal to realize high-precision casting, it is preferable to heat the wax pattern 57 at a temperature close to the upper limit temperature.

In this manner, the wax pattern 57 is heated and molten metal is poured while the cavity is kept warm. When the casting material is ferritic stainless steel, the temperature of the molten metal is set to 1400 ℃ to 1700 ℃. The temperature of the molten metal is set to a temperature equal to or higher than the melting point of the material constituting the metal plate. However, the melting point of the coating 81 forming the chamber is higher than the temperature of the molten metal.

In the casting step, the molten metal is poured into the cavity while maintaining the temperature of the cavity at a temperature close to the solidification point of the molten metal, thereby realizing high-precision casting. However, when the temperature of the chamber reaches a temperature at which abnormal oxidation occurs in the material (metal plate segment) constituting the metal plate, an oxide film is formed on the surface of the metal plate, and the oxide film interferes with melting, so that the metal plate in the chamber cannot be completely melted. Therefore, by controlling the temperature in the chamber, the oxide film is prevented from being formed on the surface of the metal plate, and the material constituting the metal plate at the end portion of the metal plate can be melted.

In the step of pressing the second inner tube segment 22 made of a metal plate, the bent portion 22b is formed in advance in the portion fitted into the wax 56, and in the step of forming the wax pattern 57, the bent portion 22b of the second inner tube segment 22 made of a metal plate is fitted into the wax 56 to form the wax pattern 57, and then the surface of the wax pattern 57 is coated with ceramic, whereby the step of forming the wax pattern 57 by spraying ceramic as a mold material (molding material) onto the surface of the wax pattern 57 to prevent the second inner tube segment 22 made of a metal plate from falling off from the wax 56.

Further, in the pressing step of the second inner tube divided body 22 made of a metal plate, the passage inner surface of the second inner tube divided body 22 is formed in advance as a surface 22d smoothly joining with the third inner tube divided body 23 made of a casting without a step, and in the molding step of the wax mold 57, the wax mold 57 is insert-molded so as to smoothly join with the passage inner surface side of the second inner tube divided body 22 made of a metal plate without a step, whereby the joint between the metal plate portion 58A and the cast portion 58B can be molded without disturbing the exhaust gas flow. That is, the surface smoothing (flush surface) for reducing the turbulence (turbulent flow) of the air flow in the inner tube 20 can be achieved.

As described above, in the casting step of manufacturing the cast segment made of a casting, one end of the metal plate segment is integrally cast into the cast portion of the cast segment to form the inner cylinder 20 of the turbine housing 10, so that the steps of welding, cutting, washing, and the like after the conventional assembly are not necessary or can be simplified (the amount of machining is reduced), and the turbine housing 10 with high accuracy can be manufactured at low cost.

Further, as shown in fig. 10, the strength of the joint portion between the metal plate portion 58A and the cast portion 58B of the molded article 58 can be improved. Further, since casting is performed, a space for movement of a welding torch (welding torch) is not required, and accordingly, the turbine housing 10 can be downsized.

The center flange 11 and the first inner tube segment 21 made of a metal plate are also formed by integrally casting the first inner tube segment 21 made of a metal plate into the center flange 11 using the mold 50.

Further, according to the above embodiment, the case where the first inner cylinder divided body, the second inner cylinder divided body, and the exhaust pipe made of a metal plate constituting the inner cylinder are cast into the third inner cylinder divided body made of a precision casting or the flange made of a casting is described, but the first outer cylinder divided body and the second outer cylinder divided body made of a metal plate constituting the outer cylinder may be cast into the flange made of a casting or the like on the exhaust gas inlet side.

The present invention has been described above based on the embodiments, but the present invention is not limited to these descriptions. For example, the metal plate material is not limited to ferritic stainless steel, and austenitic stainless steel may be used, and accordingly, austenitic stainless steel may be used as the casting material. In addition, various modifications and improvements can be made by those skilled in the art within the scope of the gist of the present invention, and the description and drawings constituting a part of the disclosure should not be construed as limiting the present invention. Various alternative embodiments, examples, and techniques for use will be readily apparent to those skilled in the art in light of this disclosure.

The present invention naturally includes various embodiments and the like not described herein. The scope of the invention should, therefore, be determined only by the specific details of the invention, which are within the scope of the claims as appropriate in the foregoing description.

The present application claims priority based on japanese patent application No. 2017-24806, applied on 12/22/2017, and on japanese patent application No. 2018-103311, applied on 30/5/2018, and the entire contents of these patent applications are incorporated by reference in the specification of the present application.

(availability in industry)

According to the present invention, when a member made of a metal plate and a member made of a cast material are integrally joined, the joint strength can be sufficiently secured, and the possibility of fatigue failure due to vibration or thermal stress in the use environment of the turbine housing can be reduced.

(description of reference numerals)

10 turbine housing

12 exhaust inlet side flange

12a opening (inlet of exhaust gas)

13 exhaust outlet side flange

13a opening (exhaust outlet)

14 turbine wheel

20 inner cylinder

21 first inner cylinder split body made of metal plate (metal plate split body)

22 second inner tube split body (metal plate split body) made of metal plate

22b bent part

22d smooth joining surfaces without steps

23 casting third inner tube segment (cast segment made of material having higher heat resistance than metal plate by casting)

50 casting mould

56 wax

57 wax model (wax original model)

81 coating

B waste gas

K-vortex exhaust gas flow path

O revolution center (center)