阅读说明：本技术 改善热等静压粉末冶金扁平状构件端面翘曲变形的方法 (Method for improving end face buckling deformation of hot isostatic pressing powder metallurgy flat component ) 是由 徐桂华 张海洋 姚草根 杜志惠 邓太庆 于 2019-10-23 设计创作，主要内容包括：本发明涉及一种改善热等静压粉末冶金扁平状构件端面翘曲变形的方法,包括(1)优化扁平状的带有台阶的盘形结构件的成形模腔结构；(2)将热等静压加载过程调整为先升温后升压的工艺。在实际生产中,该类构件常出现一定程度的翘曲、褶皱现象,导致产品报废或材料利用率的降低,对研制周期和生产成本均有较大影响。通过本发明方法的研究,以较低的生产成本解决了产品尺寸、结构变形的问题,对于提高产品质量、降低生产成本、缩短项目周期有明显的促进作用。(The invention relates to a method for improving the end face buckling deformation of a hot isostatic pressure powder metallurgy flat component, which comprises the following steps of (1) optimizing the forming die cavity structure of a flat disc-shaped structural member with steps; (2) the hot isostatic pressing loading process is adjusted to a process of first heating and then boosting. In actual production, the components often have warping and wrinkling phenomena to a certain degree, so that products are scrapped or the utilization rate of materials is reduced, and the grinding period and the production cost are greatly influenced. Through the research of the method, the problems of size and structural deformation of the product are solved at lower production cost, and the method has obvious promotion effects on improving the product quality, reducing the production cost and shortening the project period.)

1. The method for improving the end face buckling deformation of the hot isostatic pressing powder metallurgy flat component is characterized by comprising the following steps of:

(1) optimizing the forming die cavity structure of a flat disc-shaped structural member with steps;

(2) the hot isostatic pressing loading process is adjusted to a process of first heating and then boosting.

2. The method for improving end face buckling of a hot isostatic pressed powder metallurgy flat component of claim 1, wherein: the optimized forming die cavity structure comprises a die core (1), an outer sheath (2) and powder (3); a through hole or a blind hole is formed in the center of the mold core (1), so that the mold core (1) forms a tubular or barrel-shaped structure; the mold core (1) is fixed at the center of the outer sheath with a step flat disk-shaped structure, and the powder (3) is filled in a cavity formed between the mold core (1) and the outer sheath (2).

3. The method for improving end face buckling of a hot isostatic pressed powder metallurgy flat component of claim 2, wherein: the outer sheath (2) is coaxial with the mold core (1).

4. The method for improving end face buckling of a hot isostatic pressed powder metallurgy flat component of claim 2, wherein: the maximum height of the outer sheath (2) is smaller than that of the mold core (1), the top end of the outer sheath (2) retracts relative to the top end of the mold core (1), and the bottom end of the outer sheath (2) retracts delta h relative to the bottom end of the mold core (1).

5. The method of improving hot isostatic pressing of end-face buckling of a powder metallurgy flat component of claim 4, wherein: when the outer diameter d0 of the mold core (1) is more than 50mm, the mold core (1) adopts a tubular structure, t is more than or equal to 1/3d0-10mm and less than or equal to 1/3d0, delta h is more than or equal to 5mm and less than or equal to 15mm, wherein t is the wall thickness of the mold core (1).

6. The method of improving hot isostatic pressing of end-face buckling of a powder metallurgy flat component of claim 4, wherein: when the outer diameter of the mold core (1) is more than 30mm and less than or equal to d0 and less than or equal to 50mm, the mold core (1) adopts any one of a tubular structure or a barrel-shaped structure.

7. The method for improving end face buckling of a hot isostatic pressed powder metallurgy flat component of claim 6, wherein: if a tubular structure is adopted, t is more than or equal to 10mm, and delta h is more than or equal to 5mm and less than or equal to 10 mm; wherein t is the wall thickness of the mold core (1).

8. The method for improving end face buckling of a hot isostatic pressed powder metallurgy flat component of claim 6, wherein: if a barrel-shaped structure is adopted, 10mm < h1<1/3h0, t is more than or equal to 5mm, and Δ h is more than or equal to 5mm and less than or equal to 10mm, wherein t is the wall thickness of the mold core (1), h0 is the height of the mold core (1), and h1 is the thickness of the barrel bottom of the mold core (1) with the barrel-shaped structure.

9. The method of improving hot isostatic pressing of end-face buckling of a powder metallurgy flat component of claim 4, wherein: the method is characterized in that: when the outer diameter d0 of the mold core (1) is less than or equal to 30mm, the mold core adopts a barrel-shaped structure, 10mm < h1<1/3h0, t is more than or equal to 5mm, and delta h is 5mm, wherein t is the wall thickness of the mold core (1), h0 is the height of the mold core (1), and h1 is the thickness of the barrel bottom of the mold core (1) with the barrel-shaped structure.

10. The method for improving end face buckling of a hot isostatic pressed powder metallurgy flat component of claim 1, wherein: the hot isostatic pressing loading process is adjusted to a process of firstly heating and then boosting, and the process specifically comprises the following steps:

a) before the temperature is raised, the air pressure in the hearth is not more than 0.1 Mpa;

b) when the temperature is increased between room temperature and 500 ℃, the pressure is not actively pressurized, and the pressure in the hearth is kept to be not more than 10 MPa;

c) linearly pressurizing when the temperature is increased between 500 ℃ and 700 ℃, and keeping the pressure in the hearth to be not more than 80 MPa;

d) when the temperature reaches 700 ℃, preserving heat and pressure for 1-2 hours;

e) linearly pressurizing to a target pressure above 700 ℃.

Technical Field

The invention relates to a solution for solving the end face warping/deformation of a powder metallurgy flat component, which is particularly suitable for forming control of components with smaller height and diameter and larger end faces.

Background

The disc-shaped member is one of the main application directions of the powder metallurgy technology, covers various supporting discs, turbine discs and end cover parts, is widely applied to various engines of aerospace, and has a structural schematic diagram as shown in fig. 1.

In actual production, due to the difference of shrinkage of the powder blank, the end faces of the members often have different degrees of warping or wrinkling phenomena, resulting in distortion of the members, as shown in fig. 2. This results in product scrap or a reduction in material utilization, which has a large impact on both the grinding cycle and the production cost.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the problem of end face buckling deformation easily occurring in the development and production of a flat annular component, the method for improving the end face buckling deformation of the hot isostatic pressing powder metallurgy flat component is provided, and the optimization control of a forming state is realized through the work of two aspects of the structure optimization of a forming sheath and the parameter adjustment in the forming process.

The technical scheme adopted by the invention is as follows:

a method for improving the end face buckling deformation of a hot isostatic pressing powder metallurgy flat component comprises the following steps:

(1) optimizing the forming die cavity structure of a flat disc-shaped structural member with steps;

the optimized forming die cavity structure comprises a die core, an outer sheath and powder; the center of the mold core is provided with a through hole or a blind hole, so that the mold core forms a tubular or barrel-shaped structure; the mold core is fixed in the center of the outer sheath with a step flat disk-shaped structure, and the powder is filled in a cavity formed between the mold core and the outer sheath.

(2) The hot isostatic pressing loading process is adjusted to a process of first heating and then boosting.

Further, the outer sheath is coaxial with the mold core.

Furthermore, the maximum height of the outer sheath is smaller than that of the mold core, the top end of the outer sheath retracts relative to the top end of the mold core, and the bottom end of the outer sheath retracts delta h relative to the bottom end of the mold core.

Furthermore, when the outer diameter d0 of the mold core is larger than 50mm, the mold core is of a tubular structure, t is more than or equal to 1/3d0-10mm and less than or equal to 1/3d0, delta h is more than or equal to 5mm and less than or equal to 15mm, and t is the wall thickness of the mold core.

Furthermore, when the outer diameter of the mold core is more than 30mm and less than or equal to d0 and less than or equal to 50mm, the mold core structure adopts any one of a tubular structure or a barrel-shaped structure.

If a tubular structure is adopted, t is more than or equal to 10mm, and delta h is more than or equal to 5mm and less than or equal to 10 mm; wherein t is the wall thickness of the mold core.

If a barrel-shaped structure is adopted, 10mm < h1<1/3h0, t is more than or equal to 5mm, and Δ h is more than or equal to 5mm and less than or equal to 10mm, wherein t is the wall thickness of the mold core, h0 is the height of the mold core, and h1 is the thickness of the barrel bottom of the mold core with the barrel-shaped structure.

Further, when the outer diameter d0 of the mold core is not more than 30mm, the mold core adopts a barrel-shaped structure, 10mm < h1<1/3h0, t is not less than 5mm, and Δ h is 5mm, wherein t is the wall thickness of the mold core, h0 is the height of the mold core, and h1 is the thickness of the barrel bottom of the mold core with the barrel-shaped structure.

Further, the hot isostatic pressing loading process is adjusted to a process of raising the temperature and then raising the pressure, and the process specifically comprises the following steps:

a) before the temperature is raised, the air pressure in the hearth is not more than 0.1 Mpa;

b) when the temperature is increased between room temperature and 500 ℃, the pressure is not actively pressurized, and the pressure in the hearth is kept to be not more than 10 MPa;

c) linearly pressurizing when the temperature is increased between 500 ℃ and 700 ℃, and keeping the pressure in the hearth to be not more than 80 MPa;

d) when the temperature reaches 700 ℃, preserving heat and pressure for 1-2 hours;

e) linearly pressurizing to a target pressure above 700 ℃.

Compared with the prior art, the invention has the following beneficial effects:

(1) in the initial stage of forming, the sheath and the powder blank are softened along with the temperature rise, and the suspended part of the sheath can droop under the action of gravity.

(2) The height of the core mold of the sheath can be reduced by a certain amount along with the shrinkage deformation of the powder blank, so that the end face warping phenomenon caused by the incongruity of the overall shrinkage deformation of the sheath can be greatly reduced.

(3) The method can obviously improve the deformation condition of the flat disc-shaped piece, greatly reduce the material consumption of the product and avoid the product from being scrapped. Taking a certain turbine disk as an example, the end face warping amount of the traditional method reaches about 15mm, no macroscopic obvious warping exists after the method is adopted, the end face size fluctuation is only about 2mm, 1/4 raw material powder can be saved, and the machining time of 1/3 is shortened.

Drawings

FIG. 1 is a schematic view of a disc structure;

FIG. 2 is a schematic view of an end face warpage condition, wherein in FIG. 2, the upper half part is a target structural member, and the lower half part is a schematic view of deformation warpage;

FIG. 3 is a schematic view of a conventional forming die structure;

FIG. 4 is a schematic view of a modified first forming die structure;

FIG. 5 is a schematic view of a modified second forming die structure;

FIG. 6 is an example of forming die structure dimensions;

fig. 7 is an example of a hot isostatic pressing loading process.

Detailed Description

The invention is further illustrated by the following figures and examples.

The invention relates to a method for improving the end face buckling deformation of a hot isostatic pressure powder metallurgy flat component, which is particularly suitable for controlling the forming quality of an annular component with a small height-diameter ratio. The component is one of the main application directions of the powder metallurgy technology, covers various supporting disks, turbine disks and end cover parts, and is widely applied to various engines of aerospace. In actual production, the components often have warping and wrinkling phenomena to a certain degree, so that products are scrapped or the utilization rate of materials is reduced, and the grinding period and the production cost are greatly influenced. Through the research of the process technology, the problems of size and structural deformation of products are solved at lower production cost, and the process has obvious promotion effects on improving the product quality, reducing the production cost and shortening the project period.

The invention provides a method for improving the end face buckling deformation of a hot isostatic pressing powder metallurgy flat component, which is characterized by comprising the following steps of:

(1) optimizing the forming die cavity structure of a flat disc-shaped structural member with steps;

(2) the hot isostatic pressing loading process is adjusted to a process of first heating and then boosting.

The specific measures aiming at the technical scheme are as follows:

1. forming die cavity structure optimization

The annular members are each configured with a central aperture. In order to reduce material loss, a mold core is designed in a forming mold in the conventional forming process. In order to achieve a good supporting effect, the mold core usually adopts a solid structure, and the schematic structural diagram is shown in fig. 3.

The optimized forming die cavity structure comprises a die core 1, an outer sheath 2 and powder 3; a through hole or a blind hole is formed in the center of the mold core 1, so that the mold core 1 forms a tubular or barrel-shaped structure; the mold core 1 is fixed at the center of the outer sheath with a step flat disk-shaped structure, and the powder 3 is filled in a cavity formed between the mold core 1 and the outer sheath 2. The outer sheath 2 is coaxial with the mould core 1.

The maximum height of the outer sheath 2 is less than that of the mold core 1, the top end of the outer sheath 2 retracts delta h relative to the top end of the mold core 1, and the bottom end of the outer sheath 2 retracts delta h relative to the bottom end of the mold core 1.

After the powder is filled in the cavity, certain porosity is inevitably existed, and in the hot isostatic pressing process, along with the gradual densification of the powder blank, the height of the outer sheath and the powder has certain shrinkage deformation, and the solid mold core cannot be subjected to adaptive deformation, which is also an important reason for the warping of the formed sheath.

Combining the above factors, the following improvements are made to the conventional supporting mold core:

a center hole with a certain diameter is designed at the center of the mold core, so that the mold core is changed into a tubular or barrel-shaped structure from a traditional solid structure, and the specific structure is shown in fig. 4 and fig. 5 and is respectively described as follows:

when the diameter d0 of the mold core is larger than 50mm, the mold core preferably adopts the structure shown in FIG. 4, and t is more than or equal to 1/3d0-10mm and less than or equal to 1/3d0, and delta h is more than or equal to 5mm and less than or equal to 15 mm.

When the diameter of the mold core is more than 30mm and less than d0 and less than or equal to 50mm, the mold core structure can be any one of the structure shown in figure 4 or figure 5. If the structure shown in FIG. 4 is selected, t is not less than 10mm, and Δ h is not less than 5mm and not more than 10 mm. (ii) a If the structure shown in FIG. 5 is selected, it is ensured that 10mm < h1<1/3h0, t is not less than 5mm, and Δ h is not less than 5mm and not more than 10 mm. .

When the diameter d0 of the mold core is less than or equal to 30mm, the mold core adopts the structure shown in fig. 5, 10mm < h1<1/3h0, t is more than or equal to 5mm, and delta h is 5 mm.

After the structure is adopted, the mold core can generate adaptive deformation along with the shrinkage of powder in the hot isostatic pressing process, and the warping phenomenon caused by inconsistent deformation can be greatly eliminated.

2. Hot isostatic pressing loading process optimization

During hot isostatic pressing, temperature and pressure are applied to the product. Generally, the heating and pressurizing are performed simultaneously, and as the temperature increases, the pressure also increases, eventually reaching a maximum value at the same time.

Aiming at the problem of buckling deformation of a flat disc-shaped member, the loading process is adjusted to a process route of firstly heating and then boosting, and the method comprises the following specific steps:

a) before the temperature is raised, the air pressure in the hearth is not more than 0.1 Mpa;

b) when the temperature is increased between room temperature and 500 ℃, the pressure is not actively pressurized, and the pressure in the hearth is kept to be not more than 10 MPa;

c) linearly pressurizing when the temperature is increased between 500 ℃ and 700 ℃, and keeping the pressure in the hearth to be not more than 80 MPa;

d) when the temperature reaches 700 ℃, preserving heat and pressure for 1-2 hours;

linearly pressurizing to a target pressure above 700 ℃.

The embodiment of the invention is given as follows:

taking fig. 2 as an example, the standard structural member, the target structure of which is the upper half of fig. 2, is a stepped disc-shaped structural member. The diameter of the inner hole is 200mm, and the specific solving measures are as follows:

1. forming die cavity structure optimization

The diameter of the inner hole of the product is 200mm, and the mold core adopts the structure shown in figure 4, and the specific dimension is shown in figure 6. Wherein t is 60mm, and Δ h is 15 mm.

2. Hot isostatic pressing loading process optimization

The actual loading process curve is shown in fig. 7:

a) before the temperature is raised, the air pressure in the hearth is consistent with the atmospheric pressure and is 0.1 Mpa;

b) when the temperature is increased between room temperature and 500 ℃, the pressure is not actively increased, and the maximum pressure in the hearth is kept to be 6 MPa;

c) linearly pressurizing when the temperature is increased between 500 ℃ and 700 ℃, and keeping the maximum pressure in the hearth at 70 MPa;

d) when the temperature reaches 700 ℃, preserving heat and pressure for 2 hours;

e) linearly pressurizing to a target pressure above 700 ℃.

The end face warping amount of the traditional method reaches about 15mm, no macroscopic obvious warping exists after the method is adopted, the end face size fluctuation is only about 2mm, 1/4 raw material powder can be saved, and the machining time of 1/3 is shortened.

The present invention has not been described in detail, partly as is known to the person skilled in the art.