Design and Usage Method of a Formability Regulation Tooling for the Integral Bottom Component of a 5m Storage Tank

Abstract

This application relates to the field of integrated manufacturing of large-scale storage tanks for aerospace, and specifically discloses a design and usage method of a shape and property control tooling for the integral bottom component of a 5m storage tank. The shape and property control tooling with a circular outer contour is a platform for carrying the bottom product of the storage tank; an annular guiding structure is arranged on the contact surface between the shape and property control tooling and the bottom product of the storage tank, and a plurality of guiding protrusions are arranged on the side of the annular guiding structure away from the contact surface. The root of the guiding protrusion is smoothly connected to the side wall of the annular guiding structure. Before heat treatment, the opening of the bottom product of the storage tank is matched with the top of the guiding protrusion, and after heat treatment, the opening of the bottom product of the storage tank is matched with the annular guiding structure. Through the analysis of the heating and cooling processes of the bottom, fully considering the force-bearing surface of the large bottom and the process of loading and unloading the mold, the current situation of large shape and property deformation and insufficient machining margin of the large bottom is improved, laying a foundation for high-precision control of the bottom.

Description

Technical Field

[0001] This application relates to the technical field of integral manufacturing of large storage tanks for aerospace, and particularly to a design and usage method of a forming and property control tooling for the integral bottom member of a 5m storage tank. Background Art

[0002] After spinning, the state of the integral bottom member of the large storage tank is Φ4992mm×1720mm×55mm, with a weight of approximately 4.2T, and its geometric state is as shown. Figure 1 After spinning, the integral bottom member of the large storage tank needs to be heat-treated. There is a large gap in the control of furnace temperature uniformity and heat treatment deformation in domestic precision heat treatment processes compared with developed countries such as Europe and the United States. As a result, the product has a low lifespan, poor reliability, and poor safety. Only medium and low-end products can be mass-produced. Problems such as limited domestic furnace type size, low furnace temperature uniformity during heating, uneven cooling rate during cooling, and serious deformation exceeding the tolerance make it impossible to form integrally in China, unable to achieve precise and efficient manufacturing of the bottom of the tank, and difficult to meet the requirements of lightweight, high load-bearing capacity, and high reliability of the rocket body. In view of the structural characteristics of the ellipsoidal bottom member, there is currently a lack of an effective method for collaborative control of forming and properties of such workpieces after spinning in China. The core technology of forming and property control of the ellipsoidal bottom member is monopolized by foreign enterprises, and many high-end equipment or key components still rely on imports. In summary, in order to meet the requirements of coordinated forming and properties of the workpiece after spinning, higher requirements are put forward for the heat treatment deformation of the integral bottom member of the large storage tank. Summary of the Invention

[0003] In view of the problems of warping, form and position dimension differences, etc. presented by the integral bottom member of the large storage tank under extreme hot and cold working conditions during the heat treatment process, the present invention proposes a design and usage method of a forming and property control tooling for the integral bottom member of the large storage tank. Through the analysis of the heating and cooling processes of the bottom of the tank and the calculation of the thermal expansion coefficient, fully considering the force-bearing surface of the large bottom of the tank and the process of loading and unloading the mold, the present invention improves the current situation of large deformation of the form and property of the large bottom of the tank and insufficient machining margin, and lays a foundation for high-precision control of the bottom of the tank.

[0004] In the first aspect, a forming and property control tooling is provided. The forming and property control tooling is a platform for carrying the bottom product of the storage tank. The outer contour of the forming and property control tooling is circular, and the opening diameter of the bottom product of the storage tank is greater than or equal to 4 meters.

[0005] An annular guiding structure is provided on the contact surface between the shape and property control tooling and the bottom product of the storage tank. A plurality of guiding bosses are provided on the side of the annular guiding structure away from the contact surface. The plurality of guiding bosses are uniformly distributed axially. The root of the guiding boss is smoothly connected to the side wall of the annular guiding structure. Before heat treatment, the opening of the bottom product of the storage tank is matched with the top of the guiding boss. During heat treatment, the opening of the bottom product of the storage tank moves from the guiding boss to the annular guiding structure. After heat treatment, the opening of the bottom product of the storage tank is matched with the annular guiding structure.

[0006] Compared with the prior art, the solution provided by the present application at least includes the following beneficial technical effects:

[0007] In view of the problems of warping, shape and position dimensional differences, etc. presented by the overall bottom member of the large storage tank under extreme hot and cold working conditions during heat treatment, the present invention proposes a design of a shape and property control tooling for the overall bottom member of the large storage tank. Through the calculation of the coefficient of thermal expansion, the force-bearing surface of the large bottom and the process of loading and unloading the mold are fully considered, improving the current situation of large shape and property deformation and insufficient machining allowance of the large bottom, and laying a foundation for high-precision control of the bottom.

[0008] In combination with the first aspect, in some implementation manners of the first aspect, the thickness of the contact surface is greater than or equal to 40 mm, and the width of the contact surface is 75 - 90 mm.

[0009] The contact surface can be set according to the solution heat treatment temperature and coefficient of thermal expansion of aluminum alloy. The width of the contact surface can be 75 - 90 mm to ensure that the bottom of the tank will not fall off the shape and property control tooling during the expansion process, and effectively reduce the weight at the same time.

[0010] In combination with the first aspect, in some implementation manners of the first aspect, the height of the annular guiding structure is 45 - 65 mm, and the width of the annular guiding structure is 38 - 42 mm.

[0011] The annular guiding structure can be used to realize the full-profile guiding function and reserve the repair margin for the straight wall profile.

[0012] In combination with the first aspect, in some implementation manners of the first aspect, the width of the guiding boss is 200 - 300 mm, the inclination angle of the side wall of the guiding boss is 25 - 30°, and the height of the guiding boss is ⑦0 - 90 mm.

[0013] The guiding boss is reasonably arranged, so that the opening of the bottom product of the storage tank can be reasonably matched with the top of the guiding boss, and it is beneficial to smoothly move the opening of the bottom product of the storage tank to the annular guiding structure during heat treatment.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the inclination angle of the root is 10 to 12°, and the height of the root is 35 - 40 mm.

[0015] The reasonable setting of the root of the guiding boss can make the opening of the product at the bottom of the storage tank fit reasonably with the top of the guiding boss, and is conducive to the smooth movement of the opening of the product at the bottom of the storage tank to the annular guiding structure during the heat treatment process.

[0016] In combination with the first aspect, in certain implementations of the first aspect, the shape control tooling includes 4 split structures, each split structure corresponding to an arc length of 90° of the circular outer contour. Each split structure includes 3 main ribs and 3 auxiliary ribs. The main ribs extend along the radial direction of the shape control tooling, and reinforcing small ribs are arranged on the main ribs. The first auxiliary rib among the 3 auxiliary ribs is used to form the weight reduction hole of the shape control tooling, and the second auxiliary rib and the third auxiliary rib among the 3 auxiliary ribs are sequentially connected between the 3 main ribs.

[0017] The shape control tooling is in the shape of a jig, which is conducive to controlling the thermal expansion degree of the shape control tooling during the heat treatment process and is conducive to reducing the weight of the shape control tooling.

[0018] In combination with the first aspect, in certain implementations of the first aspect, the diameter of the weight reduction hole is 1900 mm.

[0019] It can achieve the purpose of increasing strength and reducing weight, prevent central stress concentration, and at the same time cooperate with the gap of the lower spray head during spray quenching to avoid blocking the water mist and affecting the cooling speed.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the material of the shape control tooling is heat-resistant ductile iron RQTSi4Mo.

[0021] This material has a large elastic modulus, good heat dissipation, good shock absorption, can withstand large impact loads, is not easy to deform during the process of alternating heat and cold, and has good corrosion resistance to organic substances and alkalis.

[0022] In the second aspect, a heat treatment method is provided. The method is applied to the shape control tooling in any of the implementations in the first aspect as described above. The method includes:

[0023] Place the product at the bottom of the storage tank on the shape control tooling and put it into the heat treatment equipment;

[0024] After the heat treatment is completed, place the product at the bottom of the storage tank on the support block, and the support block is inserted into the support groove on the contact surface;

[0025] Separate the product at the bottom of the storage tank and the shape control tooling by using a crowbar.

[0026] In view of the problems of warping, dimensional and geometric tolerance differences, etc. presented by the integral bottom member of a large storage tank under extreme hot and cold conditions during the heat treatment process, the present invention proposes a method for using a shape and property control tooling for the integral bottom member of a large storage tank. Through the calculation of the coefficient of thermal expansion, fully considering the force-bearing surface of the large bottom and the process of loading and unloading the mold, the present invention improves the current situation of large shape and property deformation and insufficient machining margin of the large bottom, and lays a foundation for the high-precision control of the bottom.

[0027] Combined with the second aspect, in some implementation manners of the second aspect, the holding temperature of the heat treatment method is 535°C ± 5°C, the holding time is 150 min - 200 min, and the cooling method is water cooling; the aging treatment method is furnace loading at temperature or heating with the furnace, the aging holding temperature is 165°C ± 5°C, the aging holding time is 20 h, and the aging cooling method is air cooling. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the 5-meter-class integral bottom structure.

[0029] Figure 2 It is a schematic diagram of the quenching tooling for the 3.35-meter-class integral bottom.

[0030] Figure 3 It is a top view of the shape and property control tooling for the integral bottom member of the 5-meter-class large storage tank.

[0031] Figure 4 It is an axonometric view of the shape and property control tooling for the integral bottom member of the 5-meter-class large storage tank.

[0032] Figure 5 It is a sectional view of the shape and property control tooling for the integral bottom member of the 5-meter-class large storage tank.

[0033] Figure 6 It is a side view of the shape and property control tooling for the integral bottom member of the 5-meter-class large storage tank.

[0034] Figure 7 It is an assembly schematic diagram of the integral bottom member of the storage tank and the shape and property control tooling.

[0035] Figure 8 It is a structural diagram of the guide protrusion setting.

[0036] Figure 9 It is a schematic diagram of the contact surface width between the product and the mold.

[0037] Figure 10 It is a schematic diagram of the common position of the furnace test piece and the lifting bolt. Detailed Embodiments

[0038] The following further describes the present application in detail with reference to the drawings and specific embodiments.

[0039] The existing quenching method is heat treatment in an air furnace circulating furnace, which is a large equipment thermal cycle heating technology and uses a basket-type material frame tooling for clamping.

[0040] Due to the relatively large furnace body of the existing air circulation furnace required, the heating temperature of aluminum alloy is about 500 °C, and the heating method mainly based on convection heating is adopted, resulting in poor temperature uniformity. The furnace temperature uniformity is only ±5 °C, directly leading to low consistency of product quality and uncontrollable heat treatment deformation.

[0041] The quenching transfer time of the existing air circulation furnace heat treatment method is relatively long, which is 16S. The quenching transfer time in the heat treatment process of international similar products is 12S. During the quenching transfer process of large and thick workpieces, the contact time with external air is relatively long, the time for the workpiece to be completely immersed in water is relatively long, and the temperature drop of each part of the workpiece is inconsistent, resulting in extremely large quenching deformation and low hardenability.

[0042] The structure of the existing quenching tooling is multi-weld point and multi-position clamping. For details, see Figure 2 , during the extremely changing process of the hot and cold at the solder joint positions, it is easy to deform and often occurs the phenomenon of welding detachment. In addition, the operation is inconvenient at the bundling positions where the steel belt tightens the workpiece, the adjusting screw cannot achieve the purpose of locking, and it is difficult to quantitatively unify the locking degree of the 6 adjusting screws. During the heat treatment process, the quenching tooling has insufficient restraint on the workpiece, and the heat treatment deformation is uncontrollable.

[0043] To solve the above problems, the present application adopts the jet spray quenching precision flexible shape and property co-regulation technology for shape and property co-regulation, and uses the high-efficiency and uniform jet spray quenching method, that is, spraying water with a certain pressure onto the surface of the workpiece to complete the quenching and cooling process of the workpiece. At this time, the cooling water impacts the surface of the workpiece, and the steam film can be quickly broken, avoiding stress and strain caused by uneven cooling of the workpiece, and solving the problems of excessive deformation of traditional large-size solution heating furnaces during water quenching and uneven properties of ellipsoidal bottom type workpieces after quenching, making it impossible to manufacture as a whole.

[0044] The bottom products of 5m-class large storage tanks can be obtained by spinning with a numerically controlled high-precision spinning device. Due to the special product object, a special shape and property co-regulation tooling is used during the heat treatment process. The shape and property co-regulation tooling is as shown in Figure 3 to Figure 6 shown, Figure 7 shows the assembly drawing of the bottom product of the storage tank and the shape and property co-regulation tooling. The opening of the bottom product of the storage tank can be placed on the shape and property co-regulation tooling. The shape and property co-regulation tooling is the bearing platform for the bottom product of the storage tank. Figure 5 In

[0045] Due to the relatively thin rib positions restricted by the weight of the shape and property control tooling and the relatively large overall size, there may be casting defects or large air holes inside the integral casting. Also, for the convenience of transportation, the shape and property control tooling adopts the process route of split casting → annealing → single-piece machining → assembly. The material of the shape and property control tooling can be selected as heat-resistant ductile iron RQTSi4Mo. This material has a large elastic modulus, good heat dissipation, good shock absorption, can withstand large impact loads, is not easily deformed during the process of alternating heat and cold, and has good corrosion resistance to organic substances and alkalis.

[0046] The outer contour of the shape and property control tooling can be circular. The shape and property control tooling can include 4 split structures. Each split structure can correspond to an arc length of 90° of the circular outer contour. As Figure 5 shown, the main body structure of each split includes 3 main ribs and 3 auxiliary ribs. The main ribs can extend along the radial direction of the shape and property control tooling. As Figure 4 shown, small ribs can also be provided on the main ribs to enhance the structural strength of the main ribs. Auxiliary rib a can be used to form the inner ring of the shape and property control tooling. The inner ring can be a weight-reducing hole of the shape and property control tooling, which can achieve the purpose of increasing strength and reducing weight, prevent central stress concentration, and at the same time cooperate with the gap of the lower spray quenching nozzle to avoid blocking the water mist and affecting the cooling speed. The diameter of the weight-reducing hole can be, for example, Φ1900mm. The remaining two auxiliary ribs b and auxiliary rib c can connect the 3 main ribs in sequence, and the auxiliary ribs b and c can be located between the auxiliary rib a and the outer contour of the shape and property control tooling.

[0047] The 4 split structures can be assembled by means of hanging platform lapping, bolt locking, and pin positioning. To prevent the shape and property control tooling and the bolts from getting stuck during the heat treatment process, boron nitride release agent is sprayed on the threaded holes and bolts. The lifting hooks, bolts, and pins can be made of 06Cr19Ni10 material, which has good high-temperature resistance, corrosion resistance and other characteristics.

[0048] The shape and property control tooling is provided with 4 lifting hooks for integral lifting to meet the use of on-site lifting tools. Considering that the parts may get stuck on the shape and property control tooling after heat treatment, the shape and property control tooling is provided with 4 lifting slots for parts, which are used in cooperation with the on-site L-shaped lifting tools.

[0049] As Figure 8 shown, the contact surface 4 between the shape and property control tooling and the bottom product of the storage tank can be used to place the bottom product of the storage tank. As Figure 8 shown, the thickness of the contact surface 4 can be greater than or equal to 40mm. The contact surface 4 can be set according to the solution temperature and thermal expansion coefficient of aluminum alloy. As Figure 9 shown, the width of the contact surface 4 can be 75 - 90mm, which can ensure that the bottom of the tank will not fall off the shape and property control tooling during the expansion process and effectively reduce the weight at the same time.

[0050] On the contact surface 4 between the shape control tooling and the bottom product of the storage tank, an annular guiding structure 9 can be provided. The annular guiding structure 9 can be used to achieve the full-profile guiding function and reserve the repair allowance for the straight-wall profile. As Figure 8 shown, the height of the annular guiding structure 9 can be 45 - 65 mm. As Figure 9 shown, the width of the annular guiding structure 9 can be 40 mm.

[0051] On the side of the annular guiding structure 9 away from the contact surface 4, a plurality of guiding bosses 6 can be provided. The number of the plurality of guiding bosses 6 can be 6 - 8. The plurality of guiding bosses 6 can be arranged axially and evenly. The guiding bosses 6 can be used to achieve the local guiding function. As Figure 8 shown, the width of the guiding boss 6 can be 200 - 300 mm. The inclination angle of the side wall of the guiding boss 6 is 25 - 30°. The height of the guiding boss 6 can be 70 - 90 mm. As Figure 9 shown, on the side of the guiding boss 6 away from the contact surface 4, a fillet can be provided. The fillet radius can be R20 mm.

[0052] The root 9 of the guiding boss 6 can be smoothly connected between the guiding boss 6 and the annular guiding structure 9. As Figure 8 shown, the inclination angle of the root 9 of the guiding boss 6 can be 10 - 12°. The height of the root 9 of the guiding boss 6 can be 35 - 40 mm.

[0053] Before heat treatment, the bottom product of the storage tank has not undergone thermal expansion, and the bottom product of the storage tank can be clamped with the top end of the guiding boss 6. As the temperature rises during the heat treatment process, the bottom product of the storage tank undergoes thermal expansion, and the outer periphery of the bottom product of the storage tank can move towards the annular guiding structure 9 and be corrected in shape by the annular guiding structure 9.

[0054] The following introduces the usage method of the shape control tooling provided by the embodiments of the present application.

[0055] (1) Furnace loading

[0056] Level the large cross-section of the integrally spun-formed large storage tank bottom, place it freely on the mold contact surface 4, and perform overall lifting through 4 lifting bolts (the locking positions of the lifting bolts are as indicated by 1 in Figure 5 ), and place it in the heat treatment equipment to ensure that the position of the shape control tooling is uniform. After the installation is stable, remove the lifting bolts to avoid collisions between the large end of the tank bottom and the lifting area during the heating process, resulting in indentations.

[0057] During the furnace loading process, pay attention that the four lifting points form a 45° angle with the feeding and discharging central axis to avoid serious collisions with the guide rail during the discharging process due to the poor rigidity of the material after heating.

[0058] As Figure 10As shown, after removing the lifting bolts, a furnace test piece can be set, and the furnace test piece can be used to replace the lifting block. The holes on the furnace test piece can correspond to the sizes and hole distances at the lifting bolt positions. During the furnace loading process, it is installed at the fastening position of the lifting bolt and fastened with bolts. The fastening force applied to the furnace test piece can be less than the fastening force applied by the lifting bolt.

[0059] (2) Heat treatment

[0060] For better product shape retention and shape maintenance, the whole process of solution and aging heat treatment is carried out with an attached shape control tooling, which plays a role in stress relaxation for the working conditions under thermal load.

[0061] Solution - Furnace loading when reaching the temperature

[0062] Insulation temperature: 535°C ± 5°C

[0063] Insulation time: 150 min - 200 min

[0064] Cooling method: Water cooling

[0065] Aging - Furnace loading when reaching the temperature / Heating up with the furnace

[0066] Insulation temperature: 165°C ± 5°C

[0067] Insulation time: 20 h

[0068] Cooling method: Air cooling

[0069] (3) Unloading

[0070] The annular guiding structure 9 can achieve deformation control and straightening of the product at the bottom of the storage tank. After the product at the bottom of the storage tank and the shape control tooling undergo integral solution treatment, the bottom of the tank is extremely likely to be stuck to Figure 8 the annular guiding structure 9 shown. After cooling, the part can be placed on Figure 6 the 4 support blocks 7 shown. The support blocks 7 can cooperate with Figure 5 the support grooves 2 shown. Through the support blocks 7, the shape control tooling can be suspended with a ground clearance of not less than 260 mm. There are 6 - 8 prying slots on the shape control tooling, and with the help of the self - weight of the shape control tooling and the force of a crowbar ( Figure 5 3 in it is the prying slot), the part and the shape control tooling are separated.

[0071] 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 defined by the scope of the claims of the present invention.

Claims

1. A shape control tooling, characterized in that The shape and property control tooling is a platform for carrying the bottom product of a 5m-level aluminum alloy storage tank. The outer contour of the shape and property control tooling is circular, and the material of the shape and property control tooling is heat-resistant ductile iron RQTSi4Mo; An annular guiding structure is arranged on the contact surface between the shape and property control tooling and the bottom product of the storage tank. A plurality of guiding bosses are arranged on one side of the annular guiding structure away from the contact surface. The plurality of guiding bosses are axially evenly distributed. The root of the guiding boss is smoothly connected to the side wall of the annular guiding structure. The height of the annular guiding structure is 45 - 65mm, and the width of the annular guiding structure is 38 - 42mm. A fillet is arranged on the side of the guiding boss away from the contact surface. The inner inclination angle of the side wall of the guiding boss is 25 - 30°. The height of the guiding boss is 70 - 90mm, the inclination angle of the root of the guiding boss is 10 - 12°, and the height of the root of the guiding boss is 35 - 40mm; Before heat treatment, the bottom product of the storage tank has not undergone thermal expansion. The opening of the bottom product of the storage tank is matched with the top of the guiding boss. During heat treatment, the bottom product of the storage tank undergoes thermal expansion, and the opening of the bottom product of the storage tank moves from the guiding boss to the annular guiding structure. After heat treatment, the opening of the bottom product of the storage tank is matched with the annular guiding structure.

2. The formability control tooling according to claim 1, characterized in that The thickness of the contact surface is greater than or equal to 40mm, and the width of the contact surface is 75 - 90mm.

3. The formability control tooling according to claim 1, characterized in that, The shape and property control tooling includes 4 split structures. Each split structure corresponds to an arc length of 90° of the circular outer contour. Each split structure includes 3 main ribs and 3 auxiliary ribs. The main ribs extend along the radial direction of the shape and property control tooling. Reinforcing small ribs are arranged on the main ribs. The first auxiliary rib among the 3 auxiliary ribs is used to form a weight reduction hole of the shape and property control tooling. The second auxiliary rib and the third auxiliary rib among the 3 auxiliary ribs are sequentially connected between the 3 main ribs.

4. The formability control tooling according to claim 3, wherein The diameter of the weight reduction hole is 1900mm.

5. A heat treatment method, characterized in that, The method is applied to the shape and property control tooling as described in any one of claims 1 to 4. The method includes: Placing the bottom product of the storage tank on the shape and property control tooling and putting it into a heat treatment device; After heat treatment is completed, placing the bottom product of the storage tank on a support block, and the support block is inserted into a support groove on the contact surface; Separating the bottom product of the storage tank and the shape and property control tooling by a crowbar.

6. The heat treatment method according to claim 5, characterized in that, The holding temperature of the heat treatment method is 535°C ± 5°C, the holding time is 150min - 200min, and the cooling method is water cooling; the aging treatment method is furnace loading at temperature or heating up with the furnace. The aging holding temperature is 165°C ± 5°C, the aging holding time is 20h, and the aging cooling method is air cooling.

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