Method for forming outer wall of section I of thrust chamber expansion section of liquid rocket engine

Abstract

The invention discloses a liquid rocket engine thrust chamber expansion section I section outer wall forming method. The integrally-formed expansion section I section outer wall part forming die is composed of an upper die body, a lower die body, a main roller and a core roller, the forming procedures include forming die forming, punching, chambering, ring rolling and machining, and the purpose of integrally forming the expansion section I section outer wall part can be achieved through the procedures. According to the method, the outer wall part of the expansion section I is integrally formed through the technological methods such as free forging, ring rolling and machining, and the problems that in the traditional forming process, the matching size machining precision is high, the welding seam strength is low, the welding period is long, and the cost is high are solved. By adopting the method for producing the outer wall part of the expansion section I, the working procedures of machining, welding, nondestructive testing and the like can be reduced, the strength of each part of the formed part is good, the forming cost is low, and the method is suitable for mass production.

Description

Technical Field

[0001] The invention relates to the technical field of liquid rocket engines, in particular to a method for forming the outer wall of an expansion section I of a thrust chamber of a liquid rocket engine. Background Art

[0002] As one of the important parts of the thrust chamber, the expansion section I of the liquid rocket engine is subjected to high temperature and high pressure gas erosion during operation. It is the part with the worst service environment of the liquid rocket engine. Therefore, extremely high requirements are placed on the overall performance of the outer wall parts of the expansion section I. In order to ensure the strength and welding performance of the front and rear sections of the expansion section I, the traditional expansion section I outer wall is welded by the front section of the expansion section I + the middle section of the expansion section I + the rear section of the expansion section I, with a total of 3 welds, such as Figure 1 shown.

[0003] The inner and outer walls of the expansion section I of the traditional liquid rocket engine thrust chamber adopt a brazing structure. The upper end of the expansion section I needs to be welded to the contraction and expansion section, and the lower end needs to be welded to the expansion section II. Therefore, the expansion section I needs to ensure the brazing characteristics of the middle section of the expansion section I and the welding strength of the front and rear sections of the expansion section I. Therefore, the outer wall of the expansion section I usually adopts a forging + plate welding structure. The above forming method has high requirements on the matching dimensional accuracy of the parts, and the weld strength after welding will reduce the matrix, resulting in an increased risk of using the outer wall of the expansion section I. Summary of the invention

[0004] The present invention provides a method for forming the outer wall of the expansion section I of the thrust chamber of a liquid rocket engine, the purpose of which is to form the outer wall parts of the expansion section I in an integrated manner, so as to solve the problems of high precision of matching size processing, low weld strength, long welding cycle and high cost in the traditional forming process. Through mechanical processing, the size of the parts of the expansion section I and the mechanical strength and welding performance of the parts of the front and rear sections of the outer wall of the expansion section I and the brazing quality of the middle section can be guaranteed.

[0005] In a first aspect, a method for forming an outer wall of an expansion section I of a liquid rocket engine thrust chamber is provided, comprising: 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 height of the parts 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 height of the part 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.

[0006] In conjunction with the first aspect, in some implementations of the first aspect, 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.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, 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.

[0008] In combination with the first aspect, in certain implementations of the first aspect, in step 1, the part is truncated cone-shaped 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.

[0009] In combination with the first aspect, in certain implementations of the first aspect, in step 1, the lower mold includes a truncated cone-shaped cavity, and the depth and height of the truncated cone-shaped cavity are 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-down 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-down fit portion is 140 mm ~ 150 mm.

[0010] In combination with the first aspect, in certain implementations of the first aspect, 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 are formed to accommodate parts to be rolled; the parts to be rolled are sleeved on the core roller, the main body of the core roller is truncated cone-shaped, and the slope of the side wall of the core roller matches the slope of the side wall of the truncated cone portion of the main roller; the parts to be rolled are pressed against the truncated cone portion of the main roller by the core roller to realize the ring rolling process.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the height of the truncated cone portion of the main roller is greater than the height of the part before and after the ring rolling.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the edge portion of the second horizontal end portion of the main roller protruding relative to the small end of the truncated cone portion has a width that is smaller than the wall thickness of the part after ring rolling.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the outer diameter of the large end of the core roller truncated cone shaped main body is 800 mm ~ 840 mm, the outer diameter of the small end is 580 mm ~ 600 mm, and the height of the core roller truncated cone shaped main body is 500 mm ~ 520 mm.

[0014] 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 transformed 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 frustum is between the minimum and maximum values ​​of the slope of the side wall of the part after mechanical processing.

[0015] Compared with the prior art, the solution provided by the present invention includes at least the following beneficial technical effects: 1. The integration of the outer wall parts of the expansion section I can reduce the processing and welding procedures of the parts. The strength of each part of the formed parts is consistent and the dimensional accuracy of the parts is high.

[0016] 2. The mold has a reasonable structure and strong versatility, and is suitable for forming parts made of raw materials such as 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the outer wall parts drawing of expansion section I of the traditional forming scheme.

[0018] Figure 2 It is a schematic diagram of the tire mold forming mold and the forming process.

[0019] Figure 3 It is a schematic diagram of a punching forming part.

[0020] Figure 4 It is a schematic diagram of the hole expansion forming part.

[0021] Figure 5 It is a schematic diagram of the ring rolling forming process.

[0022] Figure 6 It is a schematic diagram of the ring rolling forming part.

[0023] Figure 7 This is a drawing of the outer wall parts of the integrated formed expansion section I. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The present invention provides a method for forming the outer wall of the expansion section I of the thrust chamber of a liquid rocket engine. The forming process is mold forming-punching-hole expansion-ring rolling-mechanical processing, a total of 5 processes. The specific steps are as follows.

[0026] Step 1: Heat the raw material with a diameter of Φ300mm~Φ350mm and a height of 800mm~850mm to 1050℃~1120℃ for 120min~140min. After heating, place it between the upper mold 1 and the lower mold 2. Figure 2 As shown in the left figure.

[0027] The raw materials may be, for example, 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel.

[0028] like Figure 2As shown, in some embodiments, the lower mold 2 includes a truncated cone-shaped cavity, and 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 1 has a press-fit portion, which is matched with the large end opening of the truncated cone-shaped cavity of the lower mold 2, and the height of the press-fit portion is 140 mm ~ 150 mm.

[0029] Step 2: Use the upper mold 1 to press down, the pressing height is 310mm~360mm, and the part fills the cavity of the lower mold 2 after forming. Figure 2 As shown in the right figure. After pressing down, the part is in a frustum shape, the outer diameter of the large end of the part after pressing down can be 940 mm~970 mm, the outer diameter of the small end of the part after pressing down can be 540 mm~560 mm, and the height of the part after pressing down can be 490±10 mm.

[0030] Step 3: Take out the parts formed in step 2 and heat them. The heating temperature is 1050℃~1120℃ and the holding time is 120min~140min. The holding time is the same as step 1. After heating, punch the parts to form a Φ150±10mm through hole. The part height is 490±10mm. Figure 3 shown.

[0031] Step 4: Take out the parts formed in step 3 and heat them. The heating temperature of the parts is 1050℃~1120℃, and the insulation time is 100min-120min. After heating, use horse racks, horse bars and other tools to expand the holes. The wall thickness of the parts after expansion is 105±10mm, and the height of the parts is 490±10mm. Figure 4 shown.

[0032] Step 5: Take out the parts formed in step 4 and heat them. The heating temperature of the parts is 1050℃~1120℃ and the insulation time is 40min~60min. After heating, the main roller 3 and the core roller 4 are used for ring rolling. Figure 5 As shown in the figure, the wall thickness of the part after ring rolling is 30±5mm, and the height of the part is 490±5mm. Figure 6 shown.

[0033] like Figure 5As shown, in some embodiments, the main roller 3 includes a first horizontal end, a second horizontal end, and a truncated cone. The truncated cone is located between the first horizontal end and the second horizontal end, wherein the large end of the truncated cone is connected to the first horizontal end, and the small end of the truncated cone 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, and the edge portion of the second horizontal end protrudes relative to the small end of the truncated cone, so that the edge portion of the first horizontal end, the truncated cone, and the edge portion of the second horizontal end can form a part for accommodating the ring to be rolled.

[0034] Furthermore, the height of the truncated cone portion may be greater than the height of the component, for example, greater than 500 mm.

[0035] Furthermore, during the ring rolling process, the part may contact the edge of the second horizontal end. To avoid interference, the edge of the second horizontal end protruding relative to the small end of the truncated cone may have a width smaller than the wall thickness of the part after the ring rolling, for example, less than 30 mm.

[0036] like Figure 5 As shown, in some embodiments, the part to be rolled is sleeved on the core roller 4, and the main part of the core roller 4 is truncated. The part to be rolled is pressed against the truncated cone of the main roller 3 by the core roller 4 to realize the ring rolling process.

[0037] Furthermore, the outer diameter of the large end of the truncated cone-shaped main body 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 truncated cone-shaped main body of the core roller 4 is slightly larger than the height of the part to be rolled, for example, 500 to 520 mm.

[0038] Furthermore, the slope of the side wall of the core roller 4 should match the slope of the side wall of the truncated cone portion of the main roller 3. The slope of the side wall of the truncated cone portion of the main roller 3 can be designed based on the slope of the side wall of the part after the machining in step 6 is completed. Figure 7 As shown, after machining is completed, the slope of the part side wall may be slightly different at different height positions, and the slope of the side wall of the truncated cone portion of the main roller 3 may be between the minimum and maximum values ​​of the slope of the part side wall.

[0039] Step 6: Take out the part formed in step 5 and perform machining to make the part size consistent with the outer wall part size of the expansion section I formed by traditional forming, including changing the slope of the part side wall from a fixed value to a slope range that varies with height according to product design. The wall thickness of the front section of the expansion section I is 10±1mm, the wall thickness of the middle section of the expansion section I is 2±0.5mm, and the wall thickness of the rear section of the expansion section I is 4±0.5mm. Figure 7 shown.

[0040] The expansion section I outer wall parts formed by the integrated forming method can reduce the processing and welding procedures. The strength of each part of the formed parts is consistent and good, and the forming cost is low, which is suitable for mass production. The forming method provided by the present invention is used to manufacture the expansion section I outer wall integrated forming parts, and the traditional welding forming method of the front section of the expansion section I, the middle section of the expansion section I, and the rear section of the expansion section I are eliminated. Through the tire mold forming-punching-hole expansion-ring rolling-mechanical processing procedures, the formed parts are an integrated structure without other connection methods such as welding. The materials of the expansion section I outer wall integrated forming parts are 1Cr18Ni9Ti, 1Cr21Ni5Ti, S-03 steel, and S-06 steel.

[0041] The present invention aims at the structural characteristics of expansion section I. The inner and outer walls of expansion section I are formed in an integrated manner to reduce the risks brought by the welding of forgings + plate structures. The outer wall of expansion section I is a thin-walled, conical structure product. The purpose of integrated forming can be achieved by forging a ring-shaped part with a taper and then processing it. The difficulty lies in: the outer wall of expansion section I has a large end diameter of about 1000mm, a small end diameter of about 560mm, and a height of about 500mm. It is a large forging and cannot be formed in one step by forging methods such as die forging. Therefore, it is necessary to die forge the blank, punch and expand the hole to form the ring rolling blank, and design a special ring rolling tool with a taper to achieve the wall thickness and height after ring rolling. In order to ensure that the machining allowance of the outer wall of expansion section I is evenly distributed, it is necessary to design the size of the forging blank in advance, plan the forming process, and the size of the raw materials.

[0042] The process parameters are set according to 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.

[0043] Although the present invention is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on 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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