JPH0919714A - Devide for forming bent tube having special shaped cross section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve the reliability of a gas turbine by forming a bent tube having a special shape with high accuracy and at a low cost and using the bent tube having the special shape for the flow passage of the gas turbine. SOLUTION: This device is the device for forming into the bent tube 15 having the special shaped cross section by executing bending forming of a base stock having a circular cross section with internal pressure loaded on the base stock and the internal pressure is sealed by pressing apacking 9 on the outer surface of which a slope is provided against the circular tube 1 of the base stock. The packing is made of a hard packing 9b for flaring the circular tube 1 of the base stock and a soft packing 9a for sealing the internal pressure and two these processes are successively executed with the same device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus suitable for molding a curved pipe having a modified cross section used as a flow path member.

[0002]

2. Description of the Related Art There is a press molding method as one of the conventional molding methods for a curved pipe of irregular cross section. This is manufactured by cold-pressing or hot-pressing a member into which the upper and lower parts are divided into two parts, respectively, and welding the both members.

Further, in the method of forming a curved pipe of irregular cross section, as described in JP-A-55-77934, an elementary pipe having a circular cross section is formed into an irregular cross section while applying an axial tensile force and internal pressure below the yield point. A method has been used in which the upper and lower molds thus formed are pressed and the internal pressure is increased in a state where the molds are integrally held to form a curved pipe having a modified cross section. In this case, the internal pressure applied to the tube is 0
It was sealed with a ring.

[0004]

In the method of integrating two press-formed members by welding as in the above-mentioned prior art, it is necessary to process a groove having a three-dimensional curved surface in each press-formed member. It took a lot of time to work. Further, since the dimensional accuracy of each press-formed member is poor, it takes a lot of time to straighten and deform the groove surface out of the plane during welding to perform the surface alignment. Furthermore, since thermal deformation occurs when the two members are butt-welded together, there is a problem that the dimensional accuracy of the integrated curved pipe having an irregular cross section is poor.

On the other hand, in the method of forming a curved pipe of irregular cross section by applying an internal pressure and a press load of a die to a circular pipe having a circular cross section, since a thin welded pipe is used as the raw pipe, its roundness is poor. There was a drawback that the insertability of the seal member was poor. Also, as described on page 102 of the hydraulic technology manual,
If the gap between the inner diameter of the raw pipe and the outer diameter of the seal member becomes large, the internal pressure for sealing becomes extremely low, and there is a problem that the curved pipe having the irregular cross section cannot be formed. Further, there is a drawback that buckling is promoted because the tube is pulled in the axial direction during the molding process, and wrinkles easily occur in the molded product.

An object of the present invention is to provide a device which can form a curved pipe having an irregular cross section with high dimensional accuracy and in a short working time, and which is inexpensive in equipment cost.

[0007]

SUMMARY OF THE INVENTION The above object is to provide a method of forming a curved pipe having an irregular cross section by bending a material having a circular cross section while bending the material having a circular cross section with an internal pressure applied thereto. This can be achieved by flaring the end of the circular cross-section material with a packing and pressing the packing against the flared portion of the material to seal the internal pressure.

Further, the packing described above is composed of a hard packing for flaring the material circular pipe and a soft packing for sealing the internal pressure, and the flaring process of the material circular pipe and applying the internal pressure to the material circular pipe. The above object can be achieved by continuously performing the step of bending and shaping in a state to form a curved pipe having an irregular cross section with the same apparatus.

[0009]

[Function] By pressing the packing against the flared part and making the surface pressure of this part higher than the internal pressure for sealing, the roundness of the thin-walled welded pipe is corrected and the degree of freedom of insertability is increased. It is possible to seal the pressure required to form a curved pipe with a cross section. Further, since the deformation of the material circular tube in the axial direction is restrained by the seal portion, it is possible to prevent buckling which may be a concern during molding.

Further, since the packing has a double structure of a hard packing for flaring a material circular tube and a soft packing for sealing internal pressure, the cylinder in which these are mounted can be moved in the axial direction. Thus, the above-described operation can be continuously performed by the same device.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 shows a sectional view of an apparatus for integrally molding a curved pipe having an irregular cross section using a circular pipe as a raw material. In the figure, 1 is a material circular tube, 2 is an upper mold, 3a and 3b are lower molds, 4a and 4b are material holders, 5a and 5b are seal cylinders, 6 is a holder restraining hydraulic cylinder, and 7a and 7b are seals. Hydraulic cylinder for moving cylinder, 8 is hydraulic cylinder for press, 9 is seal member, 10 is seal nut, 11
Is a hydraulic pressure introduction hole, 12 is an air vent valve, 13 is a knockout hydraulic cylinder, and 14 is a pedestal.

A curved pipe having an irregular cross section is molded by using the molding apparatus shown in FIG. 1 as follows. First, the material circular tube 1 is installed in the lower molds 3a and 3b and the lower material holder 4b while the upper mold 2 and the upper material holder 4a are moved upward. Then, the upper material holder 4a is lowered by the holder restraining hydraulic cylinder 6 to tighten the material circular tube 1. In this state, as shown in FIG. 2, the seal cylinders 5a and 5b are moved forward by the seal cylinder moving hydraulic cylinders 7a and 7b to flare the end portion of the material circular pipe and press the seal member 9 with the load F to move the inside of the circular pipe. Seal. Furthermore, a liquid (pressure medium) is supplied by a pump (not shown) from the hydraulic pressure introduction hole 11 provided in the seal cylinder 5a to discharge the air in the circular pipe and fill the liquid in the circular pipe. When the liquid is filled, the air vent valve 12 provided on the seal cylinder 5b is closed, and the liquid is supplied by a pump (not shown) to apply a predetermined internal pressure p ₁ to the circular pipe. In this state, the upper die 2 is lowered by the press hydraulic cylinder 8 to apply the load W,
Each section is formed into a different shape while bending the material circular tube 1. Finally, the internal pressure in the circular pipe is increased to a predetermined value p ₂ , and the molding is completed along the upper and lower molds.

The shaped curved pipe having a modified cross section is taken out by the following procedure. Reduce the internal pressure in the circular pipe to zero,
The upper die 2 and the upper material holder 4a are raised by each hydraulic cylinder. After that, the seal cylinders 5a and 5b are retracted by the seal cylinder moving hydraulic cylinders 7a and 7b to open the mold. Finally, the knock-out hydraulic cylinder 13 raises a part 3b of the lower mold to take out the deformed cross-section curved pipe 15 formed from the lower molds 3a, 3b. In this embodiment, the knockout hydraulic cylinder 13 is shown as an example for raising a part of the lower mold, but the knockout spring can also provide the same operation.

FIG. 3 is a perspective view of a curved tube having a modified cross section formed by the apparatus shown in FIG. The curved pipe is a pipe member used as a flow path for gas or the like, and has a circular cross section on the gas inflow side and a rectangular cross section on the outflow side, and the cross section continuously changes between them. In this embodiment, as shown in FIG. 4, such curved pipes having different cross-sections are simultaneously molded in a state where two (15a, 15b) are connected in the longitudinal direction.

A detailed structure of the seal member shown in FIGS. 1 and 2 is shown in FIG. In the figure, an inclined surface having an inclination angle α is formed on a part of the inner surface of each of the material holders 4a and 4b. The packing 9 is attached to the seal cylinder 5 a and is tightened with a seal nut 10. Further, on the outer surface thereof, an inclined surface having the same angle as the inclined surfaces of the material holders 4a and 4b is formed. Further, an inclined surface having an angle β is also formed on the surface facing the seal cylinder.

As shown in FIG. 5, the seal cylinder 5a is moved forward by the seal cylinder moving hydraulic cylinder 7a to flare the end of the material circular pipe 1 and the packing 9 is pressed by the load F, so that the packing and the material circle are pressed. Surface pressure p between the pipe
By generating g, the internal pressure pi applied to the raw material circular pipe 1 is sealed. In this case, it is necessary to apply a surface pressure pg as shown in Formula 1 between the packing and the material circular pipe.

[0018]

[Equation 1] pg ≧ mpi (Equation 1) Here, m is a gasket coefficient, which is a value determined by the material of the packing and the roughness of the contact surface. Therefore, in order to reduce the surface pressure of the packing as much as possible, that is, to reduce the axial compressive load applied to the packing, the material of the packing is a copper alloy having a gasket coefficient of 3 (JIS, C3602).

The axial compressive load F, which applies the surface pressure pg necessary for sealing the internal pressure to the packing, is expressed by the equation 2 in the seal structure shown in FIG.

[0020]

F = Fs + Fp (Equation 2) where Fp is a reaction force due to the internal pressure pi and is represented by Equation 3.

[0021]

(Equation 3)

Further, the load Fs applied to the packing is expressed by the equation 4 as a function of the surface pressure pg from the balance of the force in the horizontal direction, as shown in FIG. .

[0023]

(Equation 4)

[0024]

(Equation 5)

D: Inner diameter of material circular tube (mm) dm: Average diameter of packing (mm) h: Length of packing (mm) α: Tilt angle of material holder (°) On the other hand, it acts on upper and lower material holders Vertical load Ft
Is similarly expressed by Equation 6 as a function of the surface pressure pi from the balance of forces in the vertical direction as shown in FIG.

[0026]

(Equation 6)

Here, assuming that the seal length l (= h / cosα) is constant, dm · l · m · pi is replaced with a coefficient K to make the load in the horizontal and vertical directions dimensionless. Fs
FIG. 7 shows the relationship between / K and Ft / K and the inclination angle α of the material holder. As can be seen from the figure, the horizontal load Fs required to seal the internal pressure pi sharply increases as the inclination angle α increases. In other words, the hydraulic cylinder 7a for moving the seal cylinder that applies this load
Capacity increases. On the other hand, the vertical load Ft
Gradually decreases as the inclination angle α increases. Therefore, in order to make the capacities of the seal cylinder moving hydraulic cylinder and the holder restraining hydraulic cylinder as small as possible, it is effective to set the inclination angle α of the material holder to 20 ° or less. In addition, it is desirable that the inclination angle is small from the viewpoint of the forming limit due to the elongation of the material circular pipe to be flared.

(Embodiment 2) A method of flaring the end portion of the raw material circular tube 1 with a packing 9 and sealing the internal pressure, and when the raw material circular tube is harder than the packing, packing is performed on the end surface of the raw material circular tube during flaring. It may be scratched and the seal cannot be made. In this case, the packing 9 has a structure as shown in FIG. In the figure, the packing is made of copper alloy (JIS,
C3602) packing 9a and chrome molybdenum steel (JIS, SCM440) packing 9b.
Further, on the outer surface of the packing 9a, an inclined surface whose angle matches the inclined surface of the material holder 4a is formed. further,
On the outer surface of the packing 9b, an inclined surface whose inclination angle is slightly larger than that of the inclined surface formed on the outer surface of the packing 9a is formed.

As shown in FIG. 8B, the seal cylinder 5a is moved forward by the seal cylinder moving hydraulic cylinder 7a, and first, the end portion of the raw material circular pipe 1 is flared with the hard packing 9b. After that, the seal cylinder 5a is further advanced, the packing 9a is pressed against the material circular pipe, and the surface pressure pg
Is generated to seal the internal pressure pi. It is generally said that the lower the hardness of the packing, the smaller the gasket coefficient, that is, the smaller the surface pressure required to seal the internal pressure pi. In the case of the present invention, since the inclined surface of the hard packing 9b is made larger than that of the soft packing 9a, only the soft packing 9a always contacts the inner surface of the raw material circular tube 1. Further, since the surface of the soft packing is not damaged at the end of the material circular tube, the seal does not leak.

(Embodiment 3) Another embodiment of the second embodiment is shown in FIG.
Shown in In the figure, the packing is made of soft fluororesin packing 9a and hard chrome molybdenum steel (JIS, SCM44
The packing 9b of 0) is used. Further, a backup ring 1 of a copper alloy (JIS, C3602) is used to prevent cold flow of the soft fluororesin packing 9a.
6 is provided. In the case of the present invention, since the soft fluororesin packing 9a having the gasket coefficient of 2 is used for the seal member having the internal pressure pi, the surface pressure required for sealing becomes smaller than that in the second embodiment. However, in the case of fluorine resin or the like, cold flow may occur from the contact corner portion with the seal cylinder 5a when the pressure becomes high. In order to prevent this, in the present invention, the backup ring 16 is provided. Moreover, since the position of the contact surface between the fluororesin packing 9a and the backup ring 16 is within the contact inclined surface with the material circular pipe, the effect is increased.

(Embodiment 4) FIG. 10 is a perspective view of a curved pipe with a modified cross section formed by the forming apparatus shown in FIG. The modified cross-section curved pipe in the figure is one of the components of the gas turbine, and is a component that serves as a flow path for guiding the high temperature gas burned in the combustor to the turbine blades. The gas inflow side has a circular cross section with an outer diameter of 300 mm, the outflow side has a rectangular cross section with a width of 390 mm and a height of 120 mm, and a length of 400 mm.
And, during that time, the cross section changes continuously. The perimeter of the curved pipe with a modified cross section increases from the gas inflow side toward the outflow side, and the rectangular cross section on the gas outflow side is about 1.1 times the perimeter of the circular cross section on the inflow side. The wall thickness is 5 mm. When molding a curved pipe of irregular cross section, the center of the straight pipe of stainless steel shown in FIG. 11 is shown in FIG. 11 so that the circumference of each cross section is substantially equal to the circumferential length of each cross section of the curved pipe of irregular cross section. A material circular tube is used that is formed by bulging the part to an outer diameter of 330 mm.

First, as shown in FIG. 1, with the upper mold 2 and the lower molds 3a, 3b open vertically, the material circular tube 1 having the central portion stretched out is set in the lower holder 4b. After that, the upper holder 4a is lowered by the holder restraining hydraulic cylinder 6 to tighten the material circular tube 1. In this state, the seal cylinders 5a and 5b are moved to the hydraulic cylinder 7 for moving the seal cylinder.
a and 7b, the end portion of the raw material circular tube was flared, and the sealing member 9 shown in FIG. 8 was pressed to seal the inside of the circular tube. In this case, the upper and lower holders and the soft packing 9
The inclination angle of a is 10 °, and the inclination angle of the hard packing is 11
°.

Molding of the curved pipe with a modified cross section is the same as the method shown in Example 1, but specifically, it was performed according to the process shown in FIG. First, in order to prevent buckling during the press bending process of the raw material circular tube, the material circular tube has about 7.
An internal pressure of 5 MPa is applied. In this state, lower the upper mold 2 and apply a bending load W of about 3,200 kN to the material circular pipe 1.
Each cross-section was formed into a different shape while being bent. Then, the internal pressure in the circular pipe was increased to about 25 MPa, and the circular pipe was made to follow the shapes of the upper and lower molds 2 and 3 to complete the molding. At this time, use a hydraulic cylinder for moving the seal cylinder to
A molding internal pressure of 25MPa when an axial load of 2,250kN is applied.
It was possible to mold the curved pipe with an irregular cross-section into a good shape by sealing.

In the gas turbine part molded by the above method, the circumferential lengths of the respective cross sections before and after the molding are made substantially equal to each other, so that the gas turbine parts are not locally stretched during the molding process. Is substantially equal in each cross section. Therefore, local thermal stress does not occur during use, and reliability is significantly improved. In addition, the wall thickness of the material circular pipe designed in consideration of the wall thickness reduction due to high temperature oxidation can be made uniform, and the wall thickness can be made thinner than the wall thickness of the material circular pipe designed based on the locally thin portion. .

(Fifth Embodiment) In the above-described embodiments, the flared portion at the end of the raw material circular pipe is used only for sealing the internal pressure applied to the raw material circular pipe. However, in order to improve the gas flow path characteristics, a gas turbine component in which the gas inflow side is flared at about 15 ° as shown in FIG. 13 may be used. Therefore, in the present invention, the flared portion for sealing the internal pressure is made to coincide with the flare forming portion of the gas turbine component. Therefore, in the seal structure shown in FIG. 8, the upper and lower holders and the soft packing 9a have an inclination angle of 15 °, and the hard packing has an inclination angle of 16 °, and the molding is performed in the same manner as in Example 4. At this time, an axial load of about 2,600 kN was applied to the packing by the hydraulic cylinder for moving the seal cylinder to seal the molding internal pressure of 25 MPa, and the curved pipe with a modified cross section could be molded into a good shape.

By molding the gas turbine component by the above method, the number of steps for molding the flare forming portion in a separate step can be omitted. In addition, since the curved pipe having the irregular cross section and the flare portion can be molded by the same mold and device, the accuracy is remarkably improved as compared with the case of molding in a separate process.

[0037]

According to the present invention, in a molding apparatus for a curved pipe having a modified cross section, the internal pressure applied to the curved pipe of the modified cross section is sealed by a packing having an inclined surface. Even a pipe can be molded with high accuracy by applying an internal pressure required for molding. Further, since the axial deformation of the material circular pipe is restrained by the seal portion, it is possible to mold a curved pipe having an irregular cross section in which wrinkles do not occur during the molding process.

Further, since the curved pipe having the irregular cross section can be molded with high accuracy and in the final shape, the flow path member of the gas turbine can be manufactured at a low cost and the reliability can be remarkably improved. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an apparatus for molding a modified cross-section curved pipe showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a molding device showing a process of molding a deformed cross-section curved pipe.

FIG. 3 is a perspective view of a curved pipe with a modified cross section that is molded by the molding apparatus of the present invention.

FIG. 4 is a perspective view of two curved pipes with irregular cross-sections that are connected in the molding process.

FIG. 5 is a sectional view of a seal structure showing an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the balance of forces in the seal portion.

FIG. 7 is an explanatory diagram showing a relationship between a tilt angle and a load in the seal portion.

FIG. 8 is a sectional view of a seal structure showing a second embodiment of the present invention.

FIG. 9 is a sectional view of a seal structure showing a third embodiment of the present invention.

FIG. 10 is a perspective view of a gas turbine component having a modified cross section.

FIG. 11 is a perspective view of a raw material circular tube whose central portion is stretched and formed.

FIG. 12 is an explanatory view showing a molding process of a gas turbine component having a modified cross section.

FIG. 13 is a perspective view of a gas turbine component having a modified cross section showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Material circular tube, 9a ... Soft packing, 9b ... Hard packing, 15 ... Deformed section curved tube

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location F02C 7/00 F02C 7/00 D F23R 3/42 F23R 3/42 Z (72) Inventor Yu Aratani Hitachi Ibaraki Hitachi 3-1-1, Saicho-cho, Hitachi Ltd. Hitachi factory, Hitachi (72) Inventor Takeo Kurokawa 3-1-1, Saiwaicho, Hitachi, Ibaraki Hitachi Ltd. Hitachi factory (72) Yoko Norio Baba 3-1, 1-1 Sachimachi, Hitachi, Ibaraki Hitachi, Ltd. Hitachi factory (72) Inventor Tosumi Sato 3-1-1, Sachimachi, Hitachi, Ibaraki Hitachi, Ltd. Hitachi factory ( 72) Inventor Yoshitaka Ochiai 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd., Hitachi Works

Claims (5)

[Claims] 1. A device for bending a circular cross-section material in a state where an internal pressure is applied to the circular cross-section material to form a curved pipe having an irregular cross-section, wherein the flare is formed by flaring the end of the circular cross-section material. A molding apparatus for a curved pipe of irregular cross section, wherein a packing having an inclined surface on its outer surface is pressed against the processed portion to seal the internal pressure applied to the circular cross-section material. 2. A molding apparatus for a curved pipe of irregular cross section according to claim 1, wherein the angle of the inclined surface of the packing is 20 ° or less. 3. The packing according to claim 1, wherein the packing is formed of a packing made of a material harder than the circular cross-section material and a packing made of a material lower in hardness than the packing, and the hard packing is abutted on the circular cross-section material. Forming device for curved pipes with irregular cross section. 4. A gas turbine component, characterized in that the flare forming portion on the circular cross-section side of the irregularly-shaped curved pipe is formed by pressing a packing having an inclined surface on the outer surface. 5. A gas turbine in which the gas turbine component according to claim 4 is used as a flow path for guiding gas burned in a combustor to a turbine.