Deformation control method for thin-wall special-shaped structure sheet metal part for liquid rocket engine
By using steel wire binding for vertical suspension and slow heating and cooling, the deformation problem of liquid rocket engine slot plate parts during heat treatment was solved, achieving efficient deformation control and hardness maintenance, improving product qualification rate and reducing production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN SPACE ENGINE CO LTD
- Filing Date
- 2025-07-16
- Publication Date
- 2026-05-19
AI Technical Summary
In the heat treatment process of liquid rocket engine slot plate parts, existing technologies are unable to effectively control high-temperature deformation and warping, resulting in uneven material properties, affecting hardness and first-pass yield, and increasing production costs.
The groove plate is vertically suspended by steel wire binding. It is preheated and slowly heated before quenching, protected by high-purity inert gas, and rapidly cooled and tempered after quenching to control the deformation process of the groove plate.
It effectively controls the warping and torsional deformation of the slot plate, improves the first-pass yield, reduces rework and scrap rates, lowers production costs, and improves product quality.
Smart Images
Figure CN122060969A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of sheet metal processing technology for liquid rocket engines, and in particular relates to a heat treatment deformation control method for a large-size complex thin-walled irregular structure 30CrMnSiA material channel plate (the material selection is specified according to GJB2151-94, and A should represent high-grade high-quality steel). Background Technology
[0002] The slot plate is a crucial component in the liquid rocket engine frame. This slot plate is wire-cut and sheet metal formed from 4mm thick sheet metal, featuring an irregular, asymmetrical, hollow structure. Heat treatment of the slot plate primarily involves high-temperature heating, holding, and cooling to achieve good hardness and mechanical properties. During this process, high temperatures can easily deform the metal material, altering its internal structure and microstructure, thus changing its properties. Furthermore, uneven chemical composition in the raw materials can easily occur, leading to warping and torsion deformation after cooling. Summary of the Invention
[0003] The technical problem solved by this application is to overcome the shortcomings of the prior art and, based on the forming condition of the slot plate, the heat treatment mechanism and the actual production conditions, provide a method for pre-eliminating the processing stress of the slot plate and effectively controlling the deformation during heat treatment. This method will not affect the hardness performance, and can also effectively control the warping and torsional deformation of the slot plate, improve the first pass rate, reduce rework processes and scrap rate, and save the production cost of the slot plate.
[0004] The technical solution provided in this application is as follows:
[0005] A method for controlling the deformation of thin-walled irregular-shaped sheet metal parts for liquid rocket engines, comprising:
[0006] (1) During quenching, the slot plate is vertically suspended by binding with steel wire;
[0007] (2) Fix the lower end of the groove plate in the vertical direction to prevent it from swinging during the quenching process;
[0008] (3) When quenching, first heat the quenching furnace to the preheating temperature, which is 500℃-700℃. The preheating temperature is lower than the quenching temperature. Then put the fixed slot plate parts into the quenching furnace and slowly heat them to the quenching temperature of 890~910℃. During the slow heating process, the machine stress of the slot plate is eliminated.
[0009] (4) Increase the temperature of the quenching oil to 40℃-80℃ to prevent the oil from generating a vapor film that could cause deformation of the quenching plate; remove the quenching plate from the quenching furnace and place it in the quenching oil;
[0010] (5) Remove the quenching plate from the quenching oil, clean it, and temper it.
[0011] Furthermore, the groove plate is made of 30CrMnSiA material.
[0012] Furthermore, the low-temperature furnace entry temperature mentioned in step (3) is the temperature at which the quenching furnace slowly heats up to the quenching temperature, below the quenching temperature, with the heating rate controlled at 12-18℃ / min. Excessive heating rate will cause deformation of the groove plate.
[0013] Furthermore, in step (3), the part loading temperature in the furnace is the preheating temperature (the preheating temperature is below the quenching temperature). Inert gas is introduced into the furnace to avoid severe decarburization of the parts. After the parts are put into the furnace, the temperature is increased to the quenching temperature at a heating rate of 12-18℃ / min. The holding time is calculated according to the effective size and thickness of the slot plate. After the holding time is completed, the parts are quickly taken out of the furnace and quenched in oil within 30 seconds. The slot plate is cooled in the oil tank for more than 5 minutes. When the surface temperature is ≤100℃, the parts are taken out of the oil tank.
[0014] Furthermore, the quenching oil temperature in step (4) is 40–100°C. During the quenching and cooling process of the parts, the vapor film formed on the surface hinders the heat exchange between the part surface and the cooling medium, and the vapor film ruptures at different times in different parts of the part. This causes uneven microstructural transformation during the quenching process, resulting in part deformation. That is, the low saturated vapor pressure of the cooling medium affects the quenching rate of the cooling medium, leading to different transformation times in different parts of the part, resulting in deformation. Heating the quenching oil can increase the saturated vapor pressure of the cooling medium, thereby increasing the rate of oil film evaporation and rupture, thus shortening the heat exchange time and reducing part deformation.
[0015] Furthermore, the quenching oil temperature in step (4) is above 40°C. Typically, the quenching heat treatment of the slot plate begins when the quenching oil temperature reaches above 40°C during the second batch of daily production.
[0016] Furthermore, in step (5), the slot plate is vertically suspended for quenching, cleaning, and tempering heat treatment without changing the vertical suspension method of loading into the furnace.
[0017] Furthermore, the vertical hanging fixture includes a double-layer mesh tray, a hook, and a suspension wire. The double-layer mesh tray includes a connecting rod, an upper tray, and a lower tray. The connecting rod is positioned between the upper and lower trays. Both the upper and lower trays have multiple hexagonal mesh holes. Holes are provided at both ends of the slot plate. The hook has elbows at both ends. One end of the hook passes through a hole in one section of the slot plate, and the other end is suspended in the hexagonal mesh hole of the upper tray. The slot plate is positioned between the upper and lower trays. The suspension wire passes through a hole at the other end of the slot plate and is tied to the lower tray through the hexagonal mesh hole, so that the part is vertically suspended and fixed.
[0018] Furthermore, the length of the connecting rod is adjustable so that the distance between the lower and upper trays of the double-layer mesh trays along the axial direction of the connecting rod is adjustable.
[0019] In summary, this application includes at least the following beneficial technical effects:
[0020] The heat treatment deformation control method for thin-walled irregular sheet metal parts provided by this invention involves first vertically binding and fixing the parts at both ends in a quenching basket, then placing them in a furnace at a preheating temperature set below the quenching temperature, and heating them to the quenching temperature in the furnace. At the same time, circulating high-purity inert gas with a purity of not less than 99.999% is introduced into the furnace. After quenching and heat preservation, the parts are placed in oil with a transfer time of ≤30s and a quenching oil temperature of 40~100℃. After the production line automatically runs to cool and clean the parts, they are tempered again to complete the heat treatment of the thin-walled irregular sheet metal parts.
[0021] Compared with existing technologies, the provided method not only does not affect the hardness performance, but also effectively improves the first-pass yield of thin-walled irregular sheet metal parts, reduces rework and scrap rates, lowers the production cost of heat treatment processing of sheet metal parts, and increases the first-pass yield to over 98%. Furthermore, it effectively reduces the overall flatness and torsional amplitude of thin-walled irregular sheet metal parts, achieving deformation control for large thin-walled irregular sheet metal parts used in aerospace applications, and has broad application prospects. Attached Figure Description
[0022] Figure 1 This is a structural diagram of the slot plate;
[0023] Figure 2 This is a structural diagram of a double-layer mesh material basket;
[0024] Figure 3 This is a schematic diagram of the lower tray in a double-layer mesh basket.
[0025] Figure 4 This is a schematic diagram of a hook.
[0026] Explanation of reference numerals in the attached diagram: 1. Slot plate;
[0027] 21. Double-layer mesh material basket; 22. Lifting hook;
[0028] Suspension steel wire (material 1Cr18Ni9Ti, Ф4 steel wire). Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments disclosed in this application will be described in further detail below.
[0030] like Figure 2 , Figure 3 and Figure 4As shown, the vertical hanging fixture structure used in the following embodiments or comparative examples all include a double-layer mesh tray 21, a hook 22, and a suspension wire. The double-layer mesh tray 21 includes a connecting rod, an upper tray, and a lower tray. The connecting rod is located between the upper and lower trays. Both the upper and lower trays have multiple hexagonal mesh holes. Holes are provided at both ends of the trough plate, such as... Figure 1 As shown, the hook 22 has elbows at both ends. One end of the hook 22 passes through a hole in one section of the channel plate, and the other end is suspended in the hexagonal grid holes of the upper tray. The channel plate is positioned between the upper and lower trays. The suspension wire passes through a hole at the other end of the channel plate and is tied to the lower tray through the hexagonal grid holes, so that the parts are vertically suspended and fixed. The length of the connecting rod is adjustable, so that the distance between the lower and upper trays of the double-layer grid tray 21 along the axial direction of the connecting rod is adjustable.
[0031] Example 1
[0032] This invention provides a process flow for controlling deformation during heat treatment of thin-walled irregular groove plate parts, including the following steps:
[0033] The quenching furnace is heated to 500℃ (preheating temperature). The slot plate parts are vertically suspended on the tooling by hooks, and the lower end is restrained to fix it in place. The tooling is then placed inside the quenching furnace. Nitrogen gas with a purity of not less than 99.99% is introduced into the quenching furnace, and the furnace begins to heat up at a rate of 12℃ / min to the quenching temperature of 890℃. The heating time is 120min, and the nitrogen gas supply is kept constant for 15min.
[0034] The slotted plate is automatically transferred out of the quenching furnace and placed in quenching oil for cooling. The transfer time of the slotted plate into the quenching oil is 25 seconds, the temperature of the quenching oil is 40℃, and the time of immersion of the slotted plate in the quenching oil is 10 minutes. After the slotted plate is completely immersed in the quenching oil, the quenching oil is stirred.
[0035] The trough plate was removed from the quenching oil and placed in a cleaning machine for immersion cleaning. The water temperature of the cleaning machine was 60℃ and the cleaning time was 12 minutes.
[0036] The tempering furnace is heated to 480°C. The slot plate is transferred to the tempering furnace and kept at a constant temperature. The furnace temperature is stabilized and held for 60 minutes. Then the part is transferred out and air-cooled to room temperature to complete the heat treatment of the slot plate.
[0037] Example 2
[0038] This invention provides a method for controlling deformation during heat treatment of thin-walled irregular groove plate parts, comprising the following steps:
[0039] The quenching furnace is heated to 600℃. The slot plate parts are vertically suspended on the tooling by hooks, and the lower end is constrained to fix them in place. The tooling is placed in the quenching furnace as a whole. Nitrogen gas with a purity of not less than 99.99% is introduced into the quenching furnace. The furnace is heated to the quenching temperature of 900℃ for 90 minutes. The nitrogen gas supply is kept constant and the temperature is held for 15 minutes.
[0040] The tooling and the slot plate are automatically transferred out of the quenching furnace and placed in quenching oil for cooling. The transfer time of the slot plate into the quenching oil is 25 seconds, the temperature of the quenching oil is 60℃, and the time of immersion of the slot plate in the quenching oil is 15 minutes. After the slot plate is completely immersed in the quenching oil, the quenching oil is stirred.
[0041] Remove the trough plate from the quenching oil and place it in a cleaning machine for immersion cleaning. The water temperature of the cleaning machine is 60℃ and the cleaning time is 12 minutes.
[0042] The tempering furnace is heated to 500°C. The slot plate is transferred to the tempering furnace and kept at a constant temperature. The furnace temperature is stabilized and held for 60 minutes. Then the part is transferred out and air-cooled to room temperature to complete the heat treatment of the slot plate.
[0043] Example 3
[0044] This invention provides a method for controlling deformation during heat treatment of thin-walled irregular-shaped groove plate parts, comprising the following steps:
[0045] The quenching furnace is heated to 700℃. The slot plate parts are vertically suspended on the tooling by hooks, and the lower end is constrained to fix them in place. The tooling is placed in the quenching furnace as a whole. Inert gas with a purity of not less than 99.99% is introduced into the quenching furnace. The furnace is heated to the quenching temperature of 910℃ for 60 minutes. Nitrogen gas is introduced continuously and the temperature is held for 15 minutes.
[0046] The tooling and the slot plate are automatically transferred out of the quenching furnace and placed in quenching oil for cooling. The transfer time of the slot plate into the quenching oil is 25 seconds, the temperature of the quenching oil is 80℃, and the time of immersion of the slot plate in the quenching oil is 20 minutes. After the slot plate is completely immersed in the quenching oil, the quenching oil is stirred.
[0047] Remove the tank plate from the quenching oil and place it in a cleaning machine for immersion cleaning. The water temperature of the cleaning machine is 60℃, and the cleaning time is 12 minutes.
[0048] The tempering furnace is heated to 520°C. The slot plate is transferred to the tempering furnace and kept at a constant temperature. The furnace temperature is stabilized and held for 60 minutes. Then the part is transferred out and air-cooled to room temperature to complete the heat treatment of the slot plate.
[0049] control group
[0050] The original heat treatment method includes the following steps:
[0051] The quenching furnace is heated to 900℃. The slot plate parts are vertically suspended on the tooling by hooks, with the lower end of the parts in a free hanging state. The tooling and the parts are placed in the quenching furnace as a whole. Inert gas with a purity of not less than 99.99% is introduced into the quenching furnace. The furnace is then heated back to the quenching temperature of 900℃ for 30-40 minutes and held for 15 minutes.
[0052] The tooling and the slot plate are automatically transferred out of the quenching furnace and placed in quenching oil for cooling. The transfer time of the slot plate into the quenching oil is 25 seconds, the temperature of the quenching oil is 20-30℃, and the time of immersion of the slot plate in the quenching oil is 20 minutes. After the slot plate is completely immersed in the quenching oil, the quenching oil is stirred.
[0053] Remove the tank plate from the quenching oil and place it in a cleaning machine for immersion cleaning. The water temperature of the cleaning machine is 60℃, and the cleaning time is 12 minutes.
[0054] The tempering furnace is heated to 500°C. The slot plate is transferred to the tempering furnace and kept at a constant temperature. The furnace temperature is stabilized and held for 60 minutes. Then the part is transferred out and air-cooled to room temperature to complete the heat treatment of the slot plate.
[0055] Performance testing:
[0056] The heat treatment of the thin-walled irregular-shaped groove plate was completed using the methods of Examples 1-3 respectively; the heat treatment of the groove plate was completed using the original heat treatment method as a control group.
[0057] The slot plate parts provided by each group were subjected to qualification testing, where n is the number of slot plate parts measured for each embodiment or control group, and the test results are recorded in Table 1.
[0058] Table 1. Record of Pass Rate Inspection for Slot Plates After Heat Treatment
[0059] Group n Hardness value (HRC) Maximum flatness (mm) Pass rate (%) Example 1 10 36～37 2.0 99 Example 2 10 36.5～37 2.3 98 Example 3 10 37～38 2.5 95 control group 10 36～38 4.8 48
[0060] As shown in Table 1, compared with the control group, the maximum flatness (i.e., maximum deformation) and pass rate of the slot plates in Examples 1, 2, and 3 after heat treatment were significantly better than those in the control group. However, the maximum flatness of the slot plates in each experimental group (Experimental Group 1, Experimental Group 2, and Experimental Group 3) did not differ significantly after heat treatment. The hardness of the slot plates in the experimental groups after heat treatment did not differ significantly from that in the control group, and the hardness of each experimental group (Experimental Group 1, Experimental Group 2, and Experimental Group 3) also did not differ significantly. It can be seen that the deformation control method for heat treatment of thin-walled irregular slot plate parts provided by the present invention can effectively reduce the flatness of the slot plates, improve the pass rate, reduce the production cost of processing thin-walled irregular slot plate parts, and does not affect the hardness performance compared with the prior art.
[0061] Example 4
[0062] The only difference from Example 1 is that the preheating temperature of the quenching furnace is 600°C.
[0063] Example 5
[0064] The only difference from Example 1 is that the preheating temperature of the quenching furnace is 700°C.
[0065] Comparative Example 1
[0066] The only difference from Example 1 is that after the quenching furnace reaches the quenching temperature of 890°C, the parts and tooling are directly put into the furnace as a whole, and there is no preheating process from the quenching temperature to the quenching temperature.
[0067] Comparative Example 2
[0068] The only difference from Example 1 is that the preheating temperature of the quenching furnace is 400°C.
[0069] Comparative Example 3
[0070] The only difference from Example 1 is that the preheating temperature of the quenching furnace is 800°C.
[0071] Comparative Example 4
[0072] The only difference from Example 1 is that the part is placed flat on a tray during the quenching process, and the tray is placed on the bottom plate of the furnace.
[0073] Comparative Example 5
[0074] The only difference from Example 1 is that the slot plate is automatically transferred out of the quenching furnace and placed in quenching oil for cooling, and the transfer time of the slot plate into the oil for quenching is 45 seconds.
[0075] The slot plates obtained in Examples 4-5 and the comparative examples were tested, and the test results are recorded in Table 2.
[0076] Table 2 Test results of the slot plate after heat treatment
[0077]
[0078]
[0079] The contents not described in detail in this application specification are common knowledge to those skilled in the art.
[0080] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.
Claims
1. A method for controlling the deformation of thin-walled irregular-shaped sheet metal parts for liquid rocket engines, characterized in that, include: The slotted plate is vertically suspended on a vertical hanging fixture, and both the top and bottom ends of the slotted plate are fixed. Heat the quenching furnace to the preheating temperature, which is lower than the quenching temperature. Then put the fixed slot plate parts into the quenching furnace and slowly heat them to the quenching temperature of 890-910℃. Set the quenching oil temperature to 40℃-80℃, remove the slot plate from the quenching furnace and place it in the quenching oil; Remove the slotted plate from the quenching oil, clean it, and then temper it.
2. The deformation control method for thin-walled irregular-shaped sheet metal parts for liquid rocket engines according to claim 1, characterized in that: The preheating temperature is 500℃-700℃.
3. The deformation control method for thin-walled irregular-shaped sheet metal parts for liquid rocket engines according to claim 1, characterized in that: During the process of slowly heating the furnace to the quenching temperature of 880-920℃, the heating rate is 12-18℃ / min.
4. A method for controlling the deformation of thin-walled irregular-shaped sheet metal parts for liquid rocket engines according to claim 1 or 3, characterized in that: The time from when the trough plate is taken out of the quenching furnace to when it enters the quenching oil is within 30 seconds; the cooling time of the trough plate in the quenching oil is >5 minutes, and the oil is discharged when the surface temperature of the trough plate is ≤100℃.
5. The deformation control method for thin-walled irregular-shaped sheet metal parts for liquid rocket engines according to claim 1, characterized in that: The groove plate is made of 30CrMnSiA material.
6. The deformation control method for thin-walled irregular-shaped sheet metal parts for liquid rocket engines according to claim 1, characterized in that: The vertical hanging fixture includes a double-layer mesh tray (21), a hook (22), and a suspension wire. The double-layer mesh tray (21) includes a connecting rod, an upper tray, and a lower tray. The connecting rod is located between the upper tray and the lower tray. Both the upper tray and the lower tray have multiple hexagonal mesh holes. Holes are provided at both ends of the slot plate. The hook (22) has elbows at both ends. One end of the hook (22) passes through a hole in one section of the slot plate, and the other end is suspended in the hexagonal mesh hole of the upper tray. The slot plate is located between the upper tray and the lower tray. The suspension wire passes through a hole at the other end of the slot plate and is tied to the lower tray through the hexagonal mesh hole of the lower tray, so that the parts are vertically suspended and fixed.
7. The deformation control method for thin-walled irregular-shaped sheet metal parts for liquid rocket engines according to claim 6, characterized in that: The length of the connecting rod is adjustable so that the distance between the lower and upper layers of the double-layer mesh tray (21) along the axial direction of the connecting rod is adjustable.