Forming method for outer wall of section Ⅰ of divergent section of thrust chamber of liquid rocket engine

Abstract

The present invention discloses a forming method for the outer wall of the first section of the expansion section of a liquid rocket engine. The forming die for the outer wall part of the first section of the integrally formed expansion section comprises four parts: an upper die, a lower die, a main roller, and a core roller. The forming process is die forming - punching - reaming - ring rolling - machining, a total of 5 processes. Through the above processes, the purpose of integrally forming the outer wall part of the first section of the expansion section can be achieved. The present invention integrally forms the outer wall part of the first section of the expansion section through process methods such as free forging, ring rolling, and machining, solving problems existing in the traditional forming process, such as high machining accuracy of mating dimensions, low weld strength, and high welding cycle cost. Using the present invention to produce the outer wall part of the first section of the expansion section can reduce processes such as machining, welding, and non-destructive testing. After forming, each part of the part has good consistent strength, and the forming cost is low, which is suitable for mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid rocket engines, and particularly to a method for forming the outer wall of the first section of the thrust chamber of a liquid rocket engine. Background Art

[0002] As one of the important components of the thrust chamber, the first section of the expansion section of a liquid rocket engine is subjected to high-temperature and high-pressure gas erosion during operation, and it is the component with the most severe service environment in a liquid rocket engine. Therefore, extremely high requirements are put forward for the overall performance of the outer wall parts of the first section of the expansion section. To ensure the strength and welding performance of the front section and the rear section of the first section of the expansion section, the traditional outer wall of the first section of the expansion section is welded by the front section of the first section of the expansion section + the middle section of the first section of the expansion section + the rear section of the first section of the expansion section, and there are a total of 3 welds, as Figure 1 shown.

[0003] The inner and outer walls of the first section of the expansion section of a traditional liquid rocket engine thrust chamber adopt a brazing structure. The upper end of the first section of the expansion section needs to be welded to the converging-diverging section, and the lower end needs to be welded to the second section of the expansion section. Therefore, the first section of the expansion section needs to ensure the brazing characteristics of the middle section of the first section of the expansion section and the welding strength of the front section and the rear section of the first section of the expansion section. Therefore, at present, the outer wall of the first section of the expansion section usually adopts a structure of forging + plate welding. The above forming method has high requirements for the matching dimension accuracy of parts, and the strength of the weld after welding will reduce the matrix, resulting in an increased use risk of the outer wall of the first section of the expansion section. Summary of the Invention

[0004] The present invention provides a method for forming the outer wall of the first section of the thrust chamber of a liquid rocket engine, aiming to integrally form the outer wall parts of the first section of the expansion section, and solve the problems existing in the traditional forming process, such as high machining accuracy of matching dimensions, low weld strength, long welding cycle and high cost. Through machining, the part dimensions of the first section of the expansion section and the mechanical strength, welding performance of the front section and the rear section of the outer wall of the first section of the expansion section and the brazing quality of the middle section can be ensured.

[0005] In a first aspect, a method for forming the outer wall of the first section of the thrust chamber of a liquid rocket engine is provided, including:

[0006] Step 1: Heat and keep warm a raw material with a diameter of Φ300mm - Φ350mm and a height dimension of 800mm - 850mm. The heating temperature is 1050°C - 1120°C, and the raw material is any one of 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel. After heating is completed, place it between the upper die and the lower die, and use the upper die to press down for forming. The pressing-down height is 310mm - 360mm, and after forming, the part fills the cavity of the lower die;

[0007] Step 2: After taking out the part, heat and hold it. The heating temperature is 1050°C to 1120°C. After heating, punch the part. After punching, a through hole with a diameter of Φ150±10mm is formed on the part, and the height of the part is 490±10mm;

[0008] Step 3: After taking out the part, heat and hold it. The heating temperature is 1050°C to 1120°C. After heating, ream the part. After reaming, the wall thickness value of the part is 105±10mm, and the height of the part is 490±10mm;

[0009] Step 4: After taking out the part, heat and hold it. The heating temperature is 1050°C to 1120°C. After heating, use the main roller and the core roller to perform ring rolling on the part; after ring rolling, the wall thickness value of the part is 30±5mm, and the height of the part is 490±5mm;

[0010] Step 5: After taking out the part, perform machining to make the dimensions of the part consistent with the design dimensions of the outer wall of the first section of the expansion section. Among them, the wall thickness of the front section of the first section of the expansion section is 10±1mm, the wall thickness of the middle section of the first section of the expansion section is 2±0.5mm, and the wall thickness of the rear section of the first section of the expansion section is 4±0.5mm.

[0011] Combined with the first aspect, in some implementation manners of the first aspect, the method satisfies:

[0012] The holding time in Step 1 is the same as that in Step 2;

[0013] The holding time in Step 2 > the holding time in Step 3 > the holding time in Step 4.

[0014] Combined with the first aspect, in some implementation manners of the first aspect, the method satisfies:

[0015] The holding time in Step 1 is 120 min to 140 min;

[0016] The holding time in Step 2 is 120 min to 140 min;

[0017] The holding time in Step 3 is 100 min - 120 min;

[0018] The holding time in Step 4 is 40 min to 60 min.

[0019] Combined with the first aspect, in some implementation manners of the first aspect, in Step 1, after pressing down, the part is in a frustum shape. The outer diameter of the large end of the part after pressing down is 940 mm to 970mm, the outer diameter of the small end of the part after pressing down is 540 mm to 560mm, and the height of the part after pressing down is 490±10mm.

[0020] In combination with the first aspect, in certain implementations of the first aspect, in step 1, the lower die includes a frustum-shaped cavity with a depth of 540 mm to 560 mm; the large end of the frustum-shaped cavity is located at the opening, and the inner diameter of the large end of the frustum-shaped cavity is 940 mm to 970 mm; the small end of the frustum-shaped cavity is located at the bottom of the groove, and the inner diameter of the small end of the frustum-shaped cavity is 590 mm to 620 mm; the upper die has a downward pressing and fitting portion that fits with the opening of the large end of the frustum-shaped cavity of the lower die, and the height of the downward pressing and fitting portion is 140 mm to 150 mm.

[0021] In combination with the first aspect, in certain implementations of the first aspect, in step 4, the main roll includes a first horizontal end portion, a second horizontal end portion, and a frustum portion; the frustum portion is located between the first horizontal end portion and the second horizontal end portion, where the large end of the frustum portion is connected to the first horizontal end portion, and the small end of the frustum portion is connected to the second horizontal end portion; the edge portion of the first horizontal end portion protrudes relative to the large end of the frustum portion, and the edge portion of the second horizontal end portion protrudes relative to the small end of the frustum portion. The edge portion of the first horizontal end portion, the frustum portion, and the edge portion of the second horizontal end portion form a part for accommodating the ring to be rolled; the part of the ring to be rolled is sleeved on the core roll, and the main body portion of the core roll is frustum-shaped, and the slope of the side wall of the core roll matches the slope of the side wall of the frustum portion of the main roll; the part of the ring to be rolled is pressed against the frustum portion of the main roll by the core roll to achieve the ring rolling process.

[0022] In combination with the first aspect, in certain implementations of the first aspect, the height of the frustum portion of the main roll is greater than the height of the part before and after ring rolling forming.

[0023] In combination with the first aspect, in certain implementations of the first aspect, the width of the edge portion of the second horizontal end portion of the main roll that protrudes relative to the small end of the frustum portion is less than the wall thickness value of the part after ring rolling forming.

[0024] In combination with the first aspect, in certain implementations of the first aspect, the outer diameter of the large end of the frustum-shaped main body portion of the core roll is 800 mm to 840 mm, the outer diameter of the small end is 580 mm to 600 mm, and the height of the frustum-shaped main body portion of the core roll is 500 mm to 520 mm.

[0025] In combination with the first aspect, in certain implementations of the first aspect, in step 5, the slope of the side wall of the part is changed from a fixed value to a slope range that varies with height through machining; the slope of the side wall of the frustum portion of the main roll is between the minimum value and the maximum value of the slope of the side wall of the part after machining.

[0026] Compared with the prior art, the solution provided by the present invention at least includes the following beneficial technical effects:

[0027] 1. The integration of the outer wall parts of the first section of the expansion section can reduce the processing and welding processes of the parts. After forming, the strength of each part of the part is consistent, and the dimensional accuracy of the part is high.

[0028] 2. The die structure is reasonable and has strong versatility, and is suitable for forming raw material parts such as 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the part drawing of the outer wall of the first section of the expansion section in the traditional forming scheme.

[0030] Figure 2 is the schematic diagram of the die for forming with a solid die and the forming process.

[0031] Figure 3 is the schematic diagram of the punched part.

[0032] Figure 4 is the schematic diagram of the reamed part.

[0033] Figure 5 is the schematic diagram of the ring rolling forming process.

[0034] Figure 6 is the schematic diagram of the ring rolling formed part.

[0035] Figure 7 is the part drawing of the outer wall of the first section of the expansion section formed integrally. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0037] The present invention provides a forming method for the outer wall of the first section of the thrust chamber of a liquid rocket engine. The forming process is die forging - punching - reaming - ring rolling - machining, a total of 5 processes. The specific steps are as follows.

[0038] Step 1: Heat the raw material with a diameter of Φ300mm - Φ350mm and a height dimension of 800mm - 850mm to 1050°C - 1120°C, keep it warm for 120min - 140min, and place it between the upper die 1 and the lower die 2 after heating, as shown in the left figure of Figure 2 shown.

[0039] The raw material can be, for example, 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, or S-06 steel.

[0040] As shown in Figure 2As shown, in some embodiments, the lower die 2 includes a frustum-shaped cavity with a depth of 540 mm to 560 mm. The large end of the frustum-shaped cavity is located at the opening, and the inner diameter of the large end of the frustum-shaped cavity is 940 mm to 970 mm. The small end of the frustum-shaped cavity is located at the bottom of the groove, and the inner diameter of the small end of the frustum-shaped cavity is 590 mm to 620 mm. The upper die 1 has a press-fitting portion that mates with the opening of the large end of the frustum-shaped cavity of the lower die 2, and the height of this press-fitting portion is 140 mm to 150 mm.

[0041] Step 2: Use the upper die 1 for downward pressing and forming. The downward pressing height is 310 mm to 360 mm. After forming, the part fills the cavity of the lower die 2, as shown in the right figure of Figure 2 After downward pressing, the part is frustum-shaped. The outer diameter of the large end of the part after downward pressing can be 940 mm to 970 mm, the outer diameter of the small end of the part after downward pressing can be 540 mm to 560 mm, and the height of the part after downward pressing can be 490 ± 10 mm.

[0042] Step 3: After taking out the part formed in Step 2, heat it. The heating temperature is 1050 °C to 1120 °C, and the holding time is 120 min to 140 min. The holding time is, for example, the same as that in Step 1; after heating is completed, punch holes. After punching the part, a through hole with a diameter of Φ150 ± 10 mm is formed, and the height of the part is 490 ± 10 mm, as shown in Figure 3 shown.

[0043] Step 4: After taking out the part formed in Step 3, heat it. The heating temperature of the part is 1050 °C to 1120 °C, and the holding time is 100 min - 120 min. After heating is completed, use tools such as a mandrel and a bar to expand the hole. After hole expansion, the wall thickness value of the part is 105 ± 10 mm, and the height of the part is 490 ± 10 mm, as shown in Figure 4 shown.

[0044] Step 5: After taking out the part formed in Step 4, heat it. The heating temperature of the part is 1050 °C to 1120 °C, and the holding time is 40 min to 60 min. After heating is completed, use the main roller 3 and the core roller 4 for ring rolling forming, as shown in Figure 5 shown; after ring rolling forming, the wall thickness value of the part is 30 ± 5 mm, and the height of the part is 490 ± 5 mm, as shown in Figure 6 shown.

[0045] As shown in Figure 5As shown, in some embodiments, the main roller 3 includes a first horizontal end portion, a second horizontal end portion, and a frustum portion. The frustum portion is located between the first horizontal end portion and the second horizontal end portion, wherein the large end of the frustum portion is connected to the first horizontal end portion, and the small end of the frustum portion is connected to the second horizontal end portion. The edge portion of the first horizontal end portion protrudes relative to the large end of the frustum portion, and the edge portion of the second horizontal end portion protrudes relative to the small end of the frustum portion, so that the edge portion of the first horizontal end portion, the frustum portion, and the edge portion of the second horizontal end portion can form a part for accommodating the part to be ring-rolled.

[0046] Further, the height of the frustum portion can be greater than the height of the part, for example, greater than 500 mm.

[0047] Further, during the ring-rolling process, the part can contact the edge portion of the second horizontal end portion. To avoid interference, the width of the edge portion of the second horizontal end portion protruding relative to the small end of the frustum portion can be less than the wall thickness of the part after the ring-rolling is completed, for example, less than 30 mm.

[0048] As Figure 5 shown, in some embodiments, the part to be ring-rolled is sleeved on the core roller 4, and the main body portion of the core roller 4 is frustum-shaped. The part to be ring-rolled is pressed against the frustum portion of the main roller 3 through the core roller 4 to implement the ring-rolling process.

[0049] Further, the outer diameter of the large end of the frustum-shaped main body portion of the core roller 4 is 800 mm to 840 mm, and the outer diameter of the small end is 580 mm to 600 mm; the height of the frustum-shaped main body portion of the core roller 4 is slightly greater than the height of the part to be ring-rolled, for example, 500 to 520 mm.

[0050] Further, the slope of the side wall of the core roller 4 should match the slope of the side wall of the frustum portion of the main roller 3. The slope of the side wall of the frustum portion of the main roller 3 can be designed according to the slope of the side wall of the part after machining in step six. As Figure 7 shown, after machining is completed, the slope of the side wall of the part can be slightly different at different height positions, and the slope of the side wall of the frustum portion of the main roller 3 can be between the minimum value and the maximum value of the slope of the side wall of the part.

[0051] Step six: After taking out the part formed in step five, perform machining so that the part dimensions are the same as those of the outer wall part of the expansion section I formed by traditional forming, including making the slope of the side wall of the part change from a fixed value to a slope range that changes with height according to the product design. Among them, the wall thickness of the front section of the expansion section I is 10 ± 1 mm, the wall thickness of the middle section of the expansion section I is 2 ± 0.5 mm, and the wall thickness of the rear section of the expansion section I is 4 ± 0.5 mm, as Figure 7 shown.

[0052] The outer wall parts of the first section of the expansion section formed by the integrated forming method can reduce the processing and welding processes. The strength of each part of the formed parts is consistent, the forming cost is low, and it is suitable for mass production. By using the forming method provided by the present invention to manufacture the integrated forming parts of the outer wall of the first section of the expansion section, the traditional welding forming method of the front section, the middle section, and the rear section of the first section of the expansion section is cancelled. Through the processes of die forming - punching - hole expanding - ring rolling - machining, the formed parts are of an integral structure and do not contain other connection methods such as welding. The materials of the integrated forming parts of the outer wall of the first section of the expansion section are 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel.

[0053] In view of the structural characteristics of the first section of the expansion section, the integrated forming method for the inner and outer walls of the first section of the expansion section can reduce the risks brought by the welding of the forging + plate structure. The outer wall of the first section of the expansion section is a thin-walled and tapered structure product. The purpose of integrated forming can be achieved by machining after forging a tapered ring. The difficulty lies in that the large end diameter of the outer wall of the first section of the expansion section is about 1000 mm, the small end diameter is about 560 mm, and the height is about 500 mm. It belongs to a large forging and cannot be formed in one step by forging methods such as die forging. Therefore, a die-forged blank is required, and a ring-rolled blank is formed by punching + hole expanding. A special ring-rolling tooling with a taper is designed to achieve the wall thickness and height after ring rolling. To ensure the uniform distribution of the machining allowance of the outer wall of the first section of the expansion section, the size of the forging blank needs to be designed in advance, and the forming process and the size of the raw material need to be planned.

[0054] The process parameter settings are based on the actual situation of product production. The dimensions before and after forming are set by calculating the deformation amount of each forming process, and the heating temperature and holding time are set by the optimal deformation temperature of the material.

[0055] Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the claims of the present invention.

Claims

1. A method for forming the outer wall of expansion section I of a liquid rocket engine thrust chamber, characterized in that: include: Step 1, heating and keeping warm the raw material with a diameter of Φ300mm~Φ350mm and a height of 800mm~850mm, the heating temperature is 1050℃~1120℃, and the raw material is any one of 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel; after heating, placing it between the upper mold and the lower mold, using the upper mold for downward pressing, the downward pressing height is 310mm~360mm, and the formed part fills the cavity of the lower mold; Step 2, take out the parts, heat them and keep them warm, the heating temperature is 1050℃~1120℃, punch them after heating, and form a Φ150±10mm through hole after punching, and the part height is 490±10mm; Step 3, take out the part, heat it and keep it warm, the heating temperature is 1050℃~1120℃, expand the hole after heating, the wall thickness of the part after expansion is 105±10mm, and the part height is 490±10mm; Step 4, take out the part, heat it and keep it warm, the heating temperature is 1050℃~1120℃, and after heating, use the main roller and the core roller to perform ring rolling; after the part is formed by ring rolling, the wall thickness of the part is 30±5mm, and the height of the part is 490±5mm; Step 5, after taking out the parts, perform mechanical processing to make the part size consistent with the design size of the outer wall parts of expansion section I, wherein the wall thickness of the front section of expansion section I is 10±1mm, the wall thickness of the middle section of expansion section I is 2±0.5mm, and the wall thickness of the rear section of expansion section I is 4±0.5mm.

2. The method according to claim 1, characterized in that The method satisfies: The holding time of step 1 and step 2 is the same; The holding time of step 2> the holding time of step 3> the holding time of step 4.

3. The method according to claim 1, characterized in that The method satisfies: The holding time of step 1 is 120min~140min; The holding time of step 2 is 120min~140min; The holding time of step 3 is 100min-120min; The insulation time of step 4 is 40min~60min.

4. The method according to claim 1, characterized in that: In step 1, the part is in a truncated cone shape after being pressed down, the outer diameter of the large end of the part after being pressed down is 940 mm ~970 mm, the outer diameter of the small end of the part after being pressed down is 540 mm ~560 mm, and the height of the part after being pressed down is 490±10 mm.

5. The method according to claim 4, characterized in that In step 1, the lower mold includes a truncated cone-shaped cavity, the depth of the truncated cone-shaped cavity is 540 mm ~ 560 mm; the large end of the truncated cone-shaped cavity is located at the opening, and the inner diameter of the large end of the truncated cone-shaped cavity is 940 mm ~ 970 mm; the small end of the truncated cone-shaped cavity is located at the bottom of the groove, and the inner diameter of the small end of the truncated cone-shaped cavity is 590 mm ~ 620 mm; the upper mold has a press-fit portion, which is matched with the large end opening of the truncated cone-shaped cavity of the lower mold, and the height of the press-fit portion is 140 mm ~ 150 mm.

6. The method according to claim 1, characterized in that In step 4, the main roller includes a first horizontal end, a second horizontal end, and a truncated cone portion; the truncated cone portion is located between the first horizontal end and the second horizontal end, wherein the large end of the truncated cone portion is connected to the first horizontal end, and the small end of the truncated cone portion is connected to the second horizontal end; the edge portion of the first horizontal end protrudes relative to the large end of the truncated cone portion, and the edge portion of the second horizontal end protrudes relative to the small end of the truncated cone portion, and the edge portion of the first horizontal end, the truncated cone portion, and the edge portion of the second horizontal end form a part for accommodating a part to be rolled; The parts to be ring-rolled are sleeved on the core roller, the main part of the core roller is in a truncated cone shape, and the slope of the side wall of the core roller matches the slope of the side wall of the truncated cone of the main roller; the parts to be ring-rolled are pressed against the truncated cone of the main roller through the core roller to realize the ring rolling process.

7. The method according to claim 6, characterized in that The height of the main roller truncated cone is greater than the height of the parts before and after the ring forming.

8. The method according to claim 6, characterized in that The edge portion of the second horizontal end portion of the main roller protrudes relative to the small end of the truncated cone portion, and its width is smaller than the wall thickness of the part after ring rolling.

9. The method according to claim 6, characterized in that The outer diameter of the large end of the truncated cone-shaped main body of the core roller is 800 mm ~ 840 mm, the outer diameter of the small end is 580 mm ~ 600 mm, and the height of the truncated cone-shaped main body of the core roller is 500 mm ~ 520 mm.

10. The method according to claim 6, characterized in that In step 5, the slope of the part side wall is changed from a fixed value to a slope range that varies with height according to product design through mechanical processing; the slope of the side wall of the main roller cone portion is between the minimum and maximum values ​​of the slope of the part side wall after mechanical processing.

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