Method for preparing complex thin-wall workpiece through dynamic multi-dimensional shape control technology

Abstract

The invention belongs to the technical field of powder metallurgy, and relates to a method for preparing a complex thin-wall workpiece by using a dynamic multi-dimensional shape control technology, which comprises the following steps: designing and preparing a shape control mold; the shape control mold is cleaned, and assembling and fixing of the shape control mold are completed; the assembled and fixed shape control mold is put into a prefabricated sheath, and powder filling and degassing seal welding treatment are carried out under the vacuum condition; after the degassing seal welding treatment is completed, hot isostatic pressing treatment is conducted on the whole prefabricated sheath, after the hot isostatic pressing treatment is completed, the prefabricated sheath and the shape control mold are removed, and a target workpiece blank is obtained; and performing heat treatment on the target workpiece blank to obtain the target workpiece. By means of the preparation method, the complex thin-wall workpiece can be formed at a time, accurate shape control over the workpiece is achieved, the formed target workpiece can meet the use requirement only by machining the assembly face, the forming machining amount is reduced, and meanwhile the manufacturing cost is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy and relates to a method for preparing complex thin-walled parts by utilizing dynamic multi-dimensional control technology. Background Art

[0002] As the core and key parts of aerospace equipment, complex thin-walled parts have the characteristics of thin wall, large volume and complex features. Among them, the minimum thickness of some complex thin-walled parts is only 1 mm. When the hot isostatic pressing densification operation is carried out by using ordinary package shape control means, the package has poor rigidity and is easy to deform, making the shape of the final product difficult to control.

[0003] In addition, complex thin-walled parts include many typical feature structures such as installation grooves, observation holes and bosses. According to conventional methods, they can only be prepared by first increasing the allowance for densification and then performing machining. However, this method is quite difficult in the later processing and cannot achieve stable large-scale production.

[0004] In view of this, this invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and propose a method for preparing complex thin-walled parts using dynamic multi-dimensional control technology. This method can form complex thin-walled parts in one go and can accurately control the shape. After forming, only the assembly surface needs to be machined to meet the use requirements. This solves the problem that it is difficult to accurately control the shape of thin-walled complex parts during hot isostatic pressing and the amount of processing after forming is large. This method can shorten the manufacturing cycle and effectively reduce manufacturing costs while shortening the manufacturing cost.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a complex thin-walled part by using a dynamic multi-dimensional control technology, comprising the following steps: Step 1: Design and prepare the control mold according to the target part shape; Step 2: After cleaning the control mold prepared in step 1, assemble and fix the control mold; Step 3: Place the control mold assembled and fixed in step 2 into the prefabricated package; Step 4: Under vacuum conditions, firstly load the alloy powder into the prefabricated package with the control mold in step 3, and after the powder loading is completed, perform degassing and sealing welding on the prefabricated package; Step 5: firstly perform hot isostatic pressing on the entire prefabricated package after the degassing and sealing treatment in step 4, and then remove the prefabricated package and the control mold to obtain the target part blank; Step 6: heat-treating the target workpiece blank obtained in step 5 to obtain the target workpiece.

[0007] Further, in step 1, the control mold includes a mold base, a mold shell and an inner molding core, the middle part of the mold base is fixedly connected to the inner molding core, a sliding track is arranged on the mold base, the mold shell is a split structure, located on the outer side of the inner molding core, and a groove that slides with the sliding track is arranged at the bottom of the mold shell; When using the investment casting process to prepare the control mold, low-temperature solid phase sintering is required. The sintering temperature is: 1000℃~1050℃, and the sintering time is: 6h~8h.

[0008] Furthermore, the material of the control mold is Al 2 O 3 and SiO 2 A mixture of Al 2 O 3 and SiO 2 The mass ratio is 3~5:1.

[0009] Furthermore, in step 3, the prefabricated sheath is a stainless steel sheath.

[0010] Furthermore, in step 4, at a vacuum degree of ≤1×10 -2 Under the condition of Pa, the alloy powder is loaded into a prefabricated sleeve with a controlled mold. During the powder loading process, the prefabricated sleeve needs to be vibrated with a vibration frequency of 70Hz~90Hz and an amplitude of 0.5mm~1mm.

[0011] Furthermore, after the vibration treatment, the density of the alloy powder in the prefabricated sheath is 65% to 75%.

[0012] Furthermore, in step 4, the degassing temperature in the degassing and sealing treatment is 500°C to 600°C; after the degassing and sealing treatment, the prefabricated package is tested for air tightness, and the air leakage rate is ≤1×10 -10 Pa·m 3 / s.

[0013] Furthermore, in step 5, the temperature of the hot isostatic pressing treatment is: 900°C~950°C, the heat preservation and pressure holding time is: 2h~3h, and the pressure is: 120MPa~140MPa.

[0014] Furthermore, in step 5, the density of the target workpiece blank is: 100%.

[0015] Furthermore, during the hot isostatic pressing process in step 5, the mold shell of the control mold slides and contracts inwardly along a sliding track provided on the mold base under the action of pressure.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention uses a high-strength control mold prepared by an investment casting process to perform hard control on the target part. During the densification process, the control mold does not shrink or deform, and can achieve integrated hot isostatic pressing of complex thin-walled parts, avoiding the problem of local size shortage caused by uncontrollable shrinkage of carbon steel or stainless steel cores; and the control mold material used in the invention is Al 2 O 3 and SiO 2 The mixture is sintered at a lower temperature to make the mold have a certain strength but not completely dense. 2 O 3 and SiO 2 The mixture does not react with the target part material and is easy to remove; the final integrated part greatly reduces the difficulty of subsequent processing and turning allowance, and can be produced stably in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 A flow chart of a method for preparing complex thin-walled parts using dynamic multi-dimensional control technology provided by the present invention; Figure 2 A schematic diagram of the structure of assembling the control mold prepared by the present invention; Figure 3 A physical picture of a casing prepared by the method of the present invention; Among them, 1- mold base; 2- mold shell; 3- internal molding core. DETAILED DESCRIPTION

[0020] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0021] The present invention provides a method for preparing complex thin-walled parts by using dynamic multi-dimensional control technology, such as Figure 1 As shown, the following steps are included: Step 1: Design and prepare the control mold using dynamic multi-dimensional control technology according to the target part shape.

[0022] Specifically, Figure 2 As shown, the control mold includes a mold base 1, a mold shell 2 and an inner mold core 3. The inner mold core 3 is fixedly connected to the middle of the mold base 1. Two horizontal and parallel sliding tracks are arranged on the mold base 1. The mold shell 2 is a split structure and is located on the outside of the inner mold core 3. A groove that slides with the sliding track is arranged at the bottom of the mold shell 2. The material of the control mold is Al 2 O 3 and SiO 2 A mixture of Al 2 O 3 and SiO 2 The mass ratio of Al to Al is 3~5:1. When using the investment casting process to prepare the control mold, low-temperature solid phase sintering is required to improve the strength of the control mold. The sintering temperature is: 1000℃~1050℃, and the sintering time is: 6h~8h. 2 O 3 and SiO 2 The mixture is sintered at a lower temperature and has a certain strength but is not completely dense; and 2 O 3 and SiO 2 The mixture does not react with the material of the workpiece and can be easily removed. The invention adopts the investment casting process to prepare the control mold most conveniently, and other casting processes can also be used to prepare the control mold.

[0023] Step 2: After cleaning the inner cavity of the control mold prepared in step 1, assemble and fix the control mold.

[0024] Specifically, after the control mold is prepared, it is necessary to clean the impurities and dust in the inner cavity of the control mold, and then place the split control mold in a fixed position; the inner cavity of the control mold is: the inner cavity formed by assembling and fixing the upper surface of the mold base 1, the inner surface of the mold shell 2, and the outer surface of the inner fixed core 3. Figure 2 As shown, an internal molding core 3 is placed in the middle of the mold base 1, and the interface design of the split-type control mold is a snap-on type. Correspondingly, after the groove at the bottom of the split-type mold shell 2 is matched with the sliding track set on the mold base 1 and placed, the split-type mold shell 2 is snap-on to complete the assembly.

[0025] Step 3: Place the control mold assembled and fixed in step 2 into a prefabricated sleeve, which is a stainless steel sleeve.

[0026] Step 4: Under vacuum conditions, first load the alloy powder into the prefabricated package with the controlled mold in step 3. After the powder loading is completed, the entire prefabricated package is degassed and sealed.

[0027] Specifically, at a vacuum degree of ≤1×10 -2 Pa, first load the alloy powder into a prefabricated package with a controlled mold. During the powder loading process, the prefabricated package is vibrated with a vibration frequency of 70Hz~90Hz and an amplitude of 0.5mm~1mm. After the vibration treatment, the density of the alloy powder in the prefabricated package is 65%~75%. Then, the degassing and sealing treatment is carried out, where the degassing temperature is 500℃~600℃; after the degassing and sealing treatment is completed, the entire prefabricated package is tested for air tightness, and the leakage rate needs to be ≤1×10 -10 Pa·m 3 / s. The prefabricated packages in this step are all prefabricated packages with a controlled mold.

[0028] Specifically, the alloy powder is determined by the target product to be finally formed, and high-temperature alloy powder or titanium alloy powder can be used.

[0029] Step 5: firstly perform hot isostatic pressing on the entire prefabricated package after the degassing and sealing treatment in step 4, and then remove the prefabricated package and the control mold to obtain the target part blank.

[0030] Specifically, the temperature of hot isostatic pressing is 900℃~950℃, the holding time is 2h~3h, and the pressure is 120MPa~140MPa. During the hot isostatic pressing process, the control mold shrinks inward along the sliding track set at the bottom of the prefabricated package under the action of pressure to achieve powder densification and precise control. After hot isostatic pressing, the density of the target blank is 100%.

[0031] Step 6: heat-treating the target workpiece blank obtained in step 5 to obtain the target workpiece.

[0032] Specifically, the heat treatment in the present invention adopts a standard heat treatment system. Different alloys correspond to different standard heat treatment systems. The corresponding standard heat treatment system is selected based on the alloy to be finally formed.

[0033] The method for preparing complex thin-walled parts by dynamic multi-dimensional controlled shaping provided by the present invention can prepare thin-walled parts with various complex structures.

[0034] In order to verify the beneficial effects of the preparation method of the present invention, the following examples are provided to further illustrate the effects. Example 1

[0035] This embodiment provides a method for preparing a complex thin-walled part using dynamic multi-dimensional control technology, which specifically includes the following steps: Step 1: Design and prepare the control mold according to the target part shape. The material of the control mold is Al 2 O 3 and SiO 2 A mixture of Al 2 O 3 and SiO 2 The mass ratio of is 3:1, and the control mold prepared by the investment casting process is subjected to low-temperature solid-phase sintering at a sintering temperature of 1050°C and a sintering time of 8h.

[0036] Step 2: After cleaning the inner cavity of the control mold prepared in step 1, assemble and fix the control mold.

[0037] Step 3: Place the control mold assembled and fixed in step 2 into the prefabricated package.

[0038] Step 4: At a vacuum degree of ≤1×10 -2 Pa, first load the alloy powder into the prefabricated sleeve with the control mold in step 3. During the powder loading process, the prefabricated sleeve is vibrated with a vibration frequency of 90 Hz and an amplitude of 0.5 mm. After the vibration treatment, the density of the alloy powder in the prefabricated sleeve is 75%. After the powder loading is completed, the prefabricated sleeve is degassed and sealed, where the degassing temperature is 600 ° C; after the degassed and sealed treatment, the entire prefabricated sleeve is tested for air tightness, and the leakage rate needs to be ≤1×10 -10 Pa·m 3 / s.

[0039] Step 5: First, perform hot isostatic pressing on the entire prefabricated package after degassing and sealing in step 4, and then remove the prefabricated package and the control mold to obtain the target blank. The hot isostatic pressing temperature is 900°C, the heat preservation and pressure holding time is 3h, the pressure is 140MPa, and the density of the target blank is 100%.

[0040] Step 6: Heat treat the target product blank obtained in step 5 according to a standard heat treatment system to obtain the target product. Example 2

[0041] This embodiment provides a method for preparing a complex thin-walled part using dynamic multi-dimensional control technology, which specifically includes the following steps: Step 1: Design and prepare the control mold according to the target part shape. The material of the control mold is Al 2 O 3 and SiO 2 A mixture of Al2 O 3 and SiO 2 The mass ratio of is 4:1. The controlled mold prepared by the investment casting process is subjected to low-temperature solid-phase sintering at a sintering temperature of 1025°C and a sintering time of 7h.

[0042] Step 2: After cleaning the inner cavity of the control mold prepared in step 1, assemble and fix the control mold.

[0043] Step 3: Place the control mold assembled and fixed in step 2 into the prefabricated package.

[0044] Step 4: At a vacuum degree of ≤1×10 -2 Pa, first load the alloy powder into the prefabricated sleeve with the control mold in step 3. During the powder loading process, the prefabricated sleeve is vibrated with a vibration frequency of 80 Hz and an amplitude of 0.75 mm. After the vibration treatment, the density of the alloy powder in the prefabricated sleeve is 70%. After the powder loading is completed, the prefabricated sleeve is degassed and sealed, where the degassing temperature is 550°C; after the degassed and sealed treatment, the entire prefabricated sleeve is tested for air tightness, and the leakage rate needs to be ≤1×10 -10 Pa·m 3 / s.

[0045] Step 5: First, perform hot isostatic pressing on the entire prefabricated package after degassing and sealing in step 4, and then remove the prefabricated package and the control mold to obtain the target blank. The hot isostatic pressing temperature is 925°C, the heat preservation and pressure holding time is 2.5h, the pressure is 130MPa, and the density of the target blank is 100%.

[0046] Step 6: Heat-treat the target product blank obtained in step 5 according to a standard heat treatment system to obtain the target product. Example 3

[0047] This embodiment provides a method for preparing a complex thin-walled part using dynamic multi-dimensional control technology, which specifically includes the following steps: Step 1: Design and prepare the control mold according to the target part shape. The material of the control mold is Al 2 O 3 and SiO 2 A mixture of Al 2 O 3 and SiO 2 The mass ratio of is 5:1. When the control mold is prepared by investment casting process, low-temperature solid phase sintering is carried out at a sintering temperature of 1000℃ and a sintering time of 6h.

[0048] Step 2: After cleaning the inner cavity of the control mold prepared in step 1, assemble and fix the control mold.

[0049] Step 3: Place the control mold assembled and fixed in step 2 into the prefabricated package.

[0050] Step 4: At a vacuum degree of ≤1×10 -2 Pa, first load the alloy powder into the prefabricated sleeve with the control mold in step 3. During the powder loading process, the prefabricated sleeve is vibrated with a vibration frequency of 70 Hz and an amplitude of 1 mm. After the vibration treatment, the density of the alloy powder in the prefabricated sleeve is 65%. After the powder loading is completed, the prefabricated sleeve is degassed and sealed, where the degassing temperature is 500 ° C; after the degassed and sealed treatment, the entire prefabricated sleeve is tested for air tightness, and the leakage rate needs to be ≤1×10 -10 Pa·m 3 / s.

[0051] Step 5: First, perform hot isostatic pressing on the entire prefabricated package after degassing and sealing in step 4, and then remove the prefabricated package and the control mold to obtain the target blank. The hot isostatic pressing temperature is 950°C, the heat preservation and pressure holding time is 2h, the pressure is 120MPa, and the density of the target blank is 100%.

[0052] Step 6: Heat-treat the target product blank obtained in step 5 according to a standard heat treatment system to obtain the target product.

[0053] According to an embodiment of the present invention, Figure 3 As shown, the present invention also provides a real picture of a casing prepared by the method of the present invention. It is only necessary to open a structure with the casing boss shown in the figure on the mold shell 2 provided by the present invention to obtain a casing component with a boss integrally formed on the outside.

[0054] According to an embodiment of the present invention, a method for preparing complex thin-walled parts using dynamic multi-dimensional control technology provided by the present invention uses a high-strength control mold for hard control, and the control mold can achieve multi-dimensional radial movement in the prefabricated sleeve, thereby solving the molding problem of complex thin-walled parts. The high-strength mold prepared by the investment casting method of the present invention, the mold shell 2 and the internal mold core 3 contain all the geometric features of the final part, and the bottom of the mold base 1 is provided with a sliding track. During the hot isostatic pressing process, the mold shell 2 slides inward along the sliding track, while the internal mold core 3 is fixed, and then the alloy powder is extruded to achieve densification, thereby realizing the hot isostatic pressing integrated molding of complex thin-walled parts.

[0055] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0056] It should be understood that the present invention is not limited to the above-described content and can be variously modified and changed without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for preparing complex thin-walled parts using dynamic multi-dimensional control technology, characterized in that: The steps include: Step 1: Design and prepare the control mold according to the target part shape; Step 2: After cleaning the control mold prepared in step 1, assemble and fix the control mold; Step 3: Place the control mold assembled and fixed in step 2 into the prefabricated package; Step 4: Under vacuum conditions, firstly load the alloy powder into the prefabricated package with the control mold in step 3, and after the powder loading is completed, perform degassing and sealing welding on the prefabricated package; Step 5: firstly perform hot isostatic pressing on the entire prefabricated package after the degassing and sealing treatment in step 4, and then remove the prefabricated package and the control mold to obtain the target part blank; Step 6: heat-treating the target workpiece blank obtained in step 5 to obtain the target workpiece.

2. The method for preparing complex thin-walled parts using dynamic multi-dimensional control technology according to claim 1, characterized in that: In step 1, the control mold comprises a mold base (1), a mold shell (2) and an inner mold core (3), the middle part of the mold base (1) is fixedly connected to the inner mold core (3), a sliding track is arranged on the mold base (1), the mold shell (2) is a split structure, located outside the inner mold core (3), and a groove that slides in cooperation with the sliding track is arranged at the bottom of the mold shell (2); When using the investment casting process to prepare the control mold, low-temperature solid phase sintering is required. The sintering temperature is: 1000℃~1050℃, and the sintering time is: 6h~8h.

3. The method for preparing complex thin-walled parts using dynamic multi-dimensional control technology according to claim 1, characterized in that: The material of the control mold is a mixture of Al2O3 and SiO2, wherein the mass ratio of Al2O3 to SiO2 is 3-5:

1.

4. The method for preparing complex thin-walled parts using dynamic multi-dimensional control technology according to claim 1, characterized in that: In step 3, the prefabricated sheath is a stainless steel sheath.

5. The method for preparing complex thin-walled parts using dynamic multi-dimensional control technology according to claim 1, characterized in that: In step 4, the vacuum degree is ≤1×10 -2 Under the condition of Pa, the alloy powder is loaded into a prefabricated sleeve with a controlled mold. During the powder loading process, the prefabricated sleeve needs to be vibrated with a vibration frequency of 70Hz~90Hz and an amplitude of 0.5mm~1mm.

6. The method for preparing complex thin-walled parts by using dynamic multi-dimensional control technology according to claim 5, characterized in that: After the vibration treatment, the density of the alloy powder in the prefabricated package is 65% to 75%.

7. The method for preparing complex thin-walled parts by using dynamic multi-dimensional control technology according to claim 1, characterized in that: In step 4, the degassing temperature of the degassing and sealing treatment is 500°C to 600°C. After the degassing and sealing treatment, the entire prefabricated package is tested for air tightness, and the leakage rate is ≤1×10 -10 Pa·m 3 / s.

8. The method for preparing complex thin-walled parts using dynamic multi-dimensional control technology according to claim 1, characterized in that: In step 5, the temperature of the hot isostatic pressing treatment is: 900° C.~950° C., the heat preservation and pressure holding time is: 2h~3h, and the pressure is: 120MPa~140MPa.

9. The method for preparing complex thin-walled parts using dynamic multi-dimensional control technology according to claim 1, characterized in that: The density of the target workpiece blank in step 5 is: 100%.

10. The method for preparing complex thin-walled parts by using dynamic multi-dimensional control technology according to claim 1, characterized in that: During the hot isostatic pressing process in step 5, the mold shell (2) of the control mold slides inwards and contracts along the sliding track provided on the mold base (1) under the action of pressure.

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