A method for connecting a tank three-in-one structure without defects

Abstract

The application discloses a kind of storage tank three-in-one structure defectless connection method, belong to welding technical field.The method is first to the double-pass welding test of simulation piece, obtains the welding parameter satisfying design requirement;Again according to the three-in-one structure of the product to be welded double-pass sectional welding is carried out according to welding parameter, forms defectless weld.The application adopts close-range double-pass weld process, by reasonable sectional control welding length, ensure that the temperature of half membrane is lower than the requirement of design document, under the premise of realizing the high-quality welding of product, the welding temperature of product is strictly controlled.The first welding qualification rate of product is improved from 30% to more than 95%.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of storage tank three-in-one structure defect-free connection method, belong to welding technical field. BACKGROUND

[0002] The storage tank is the device that control and store propellant for attitude control propulsion system, and is one of the core components of attitude control propulsion system, and it accounts for a large part of the mass and space of attitude control propulsion system, and then affects the overall performance of the whole propulsion system.The storage tank is mainly welded by three components of air cavity assembly, liquid cavity assembly and management device, and the welding position is mostly three-in-one welding structure, and high-strength and reliable connection of three is realized by using welding process.

[0003] When the storage tank product is welded, the temperature of the welding seam part reaches more than 2000 DEG C, in order to prevent the management device half membrane from being burned or aged by heat, the temperature of the plastic half membrane 10mm away from the welding seam needs to be controlled to be not higher than 120 DEG C.In addition, as a high-pressure container, the storage tank has very high requirements for the strength of the welding seam, and the storage tank three-in-one welding seam needs to reach the requirements of grade I welding seam.

[0004] When the traditional welding process is used for welding the storage tank, the welding of the product is generally completed by one-time welding.During the welding process, the half membrane is easily burned due to high welding temperature, which leads to product scrap.Meanwhile, in order to strictly control the welding temperature, the welding heat input is insufficient, which leads to unstable welding process, and pores are easily present in the welding seam, which leads to repeated repair welding of the product, and greatly affects the production efficiency and product quality stability of the product. SUMMARY

[0005] The technical problem solved by the present application is to overcome the shortcomings of the prior art, and a kind of storage tank three-in-one structure defect-free connection method is provided, which adopts double-channel segmented welding method to realize effective control of welding defects.

[0006] The technical solution of the present application is:

[0007] A kind of storage tank three-in-one structure defect-free connection method, comprising:

[0008] Process air cavity assembly simulation piece, liquid cavity assembly simulation piece, management device simulation piece, assemble the above-mentioned three simulation pieces, double-channel welding is carried out on the three-in-one structure formed after assembly, and a storage tank test piece is obtained;whether the temperature of the test piece during welding meets the design requirements is detected, if it meets the requirements, the welding parameters used during welding are selected as the selected welding parameters;

[0009] The air cavity assembly product, liquid cavity assembly product and management device product to be welded are cleaned and assembled, and the three-in-one structure formed after assembly is welded by using segmented welding process based on the selected welding parameters;After the product is welded, the welding seam is subjected to X-ray inspection.

[0010] Preferably, the three-in-one structure formed after assembly is double-welded, including:

[0011] The minimum distance between the plastic half membrane and the weld on the measurement management device simulation is measured, and a temperature measuring device is placed at the equidistant position of the weld to measure the temperature during the welding process.

[0012] The butt joint surfaces of the gas cavity assembly simulation and the management device simulation, and the butt joint surfaces of the liquid cavity assembly simulation and the management device simulation are respectively electron beam welded; the interval between the above two weldings is 10-25 min, and the welding parameters are: acceleration voltage is 40-150 KV, vacuum chamber vacuum degree is 10 0 ~ 10 -2 Pa, welding speed is 0.5-4 m / min, and welding current is 8-20 mA.

[0013] Preferably, the temperature of the test piece and whether the weld meets the design requirements during the welding process are detected, including:

[0014] According to the temperature value measured by the temperature measuring device, the peak temperature is required to be less than the highest temperature required by the design;

[0015] The weld is cut and inspected to check the weld penetration, the fusion width of the root of the management device test piece, and the internal quality of the weld, and the design requires that the weld penetration be greater than the shell wall thickness of the gas cavity assembly simulation by 0.5-2.5 mm, greater than the shell wall thickness of the liquid cavity assembly simulation by 0.5-2.5 mm, the fusion width be greater than the rib width of the management device simulation by 0.5-3 mm, and there be no welding defects in the weld.

[0016] Preferably, the three-in-one structure formed after assembly is first positioned and welded, and then double-welded after an interval of 5-15 min; the positioning welding adopts electron beam welding, and the electron beam current acts on the center of the management device rib, and the welding current is 8-15 mA.

[0017] Preferably, the assembly of the gas cavity assembly simulation, the liquid cavity assembly simulation, and the management device simulation needs to meet the requirement that the assembly gap between the simulations is not greater than 0.1 mm.

[0018] Preferably, based on the selected welding parameters, the three-piece product is welded using a segmented welding process, after completing a segment of welding, the product is turned by 180° for the next segment of welding, until all welds are welded; wherein, the length of each segment of welding is subject to the requirement that the temperature of the plastic half membrane in the management device product does not exceed the highest temperature required by the design.

[0019] Preferably, the length of each segment of welding is 100-250 mm.

[0020] Preferably, before the double-channel welding is carried out, a special welding tool is used to assist the double-channel welding, and the special welding tool comprises a purple copper holding ring and an aluminum alloy connecting structure, and the purple copper holding ring is arranged at a welding area 3-40 mm away from the welding seam.

[0021] Preferably, a gas cavity assembly simulation piece, a liquid cavity assembly simulation piece and a management device simulation piece are processed, when the welding seam diameter is not greater than 100 mm, the three simulation pieces are all simulated by ring pieces, the diameters of the ring pieces are consistent with the to-be-welded products, the gas cavity assembly simulation piece and the liquid cavity assembly simulation piece are consistent with the thicknesses of the corresponding products, the rib width, the rib height and the thickness of the lock bottom of the management device simulation piece are completely same as the product, when the welding seam diameter is greater than 100 mm, the same material flat plate is used to simulate each to-be-welded product, the thicknesses of the gas cavity assembly simulation piece and the liquid cavity assembly simulation piece and the rib width and the thickness of the lock bottom of the management device simulation piece are consistent with the corresponding products, the width of each simulation piece is not less than 50 mm, and the length of each simulation piece is not less than 100 mm.

[0022] Preferably, the to-be-welded gas cavity assembly product, the to-be-welded liquid cavity assembly product and the to-be-welded management device product are cleaned, and the oxide film on the product surface in a range of 10 mm of the welding seam is removed during the cleaning.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] The present application adopts the segmented double-channel welding seam to perform the welding of the three-in-one structure, effectively solves the problems of the multiple welding seam porosity defects, incomplete fusion and incomplete penetration which are prone to exist in the traditional single-welding seam integrated welding. When the close-range double-channel welding process is adopted, the welding length is controlled by segmentation, the temperature at the half membrane is ensured to be lower than the requirement in the design document, the welding temperature of the product is strictly controlled on the premise of realizing the high-quality welding of the product, and the one-time welding qualification rate of the product is increased from 30% to more than 95%. BRIEF DESCRIPTION OF DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments and are not intended to be a limitation on the application. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. In the drawings:

[0026] Figure 1 A schematic view of a storage tank and a three-in-one structure of an embodiment of the present application;

[0027] Figure 2 A schematic view of welding by using a traditional welding method of an embodiment of the present application;

[0028] Figure 3 A schematic view of the welding appearance by using a traditional welding method of an embodiment of the present application;

[0029] Figure 4A double-channel welding process schematic diagram for the storage tank embodiment of the present application;

[0030] Figure 5 A double-channel welding seam appearance schematic diagram for the storage tank embodiment of the present application;

[0031] Figure 6 A product attachment schematic diagram for the storage tank embodiment of the present application. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0033] As shown in Figure 1 , the storage tank described in the present application mainly consists of a gas cavity assembly, a liquid cavity assembly and a management device, the connection parts of the three are a three-in-one structure, and the reliable connection of the three is achieved by using a welding process. After welding, the gas cavity and the liquid cavity are completely isolated by the management device, and the high temperature generated during welding cannot damage the semi-membrane on the management device, and the temperature of any part of the semi-membrane should not exceed the maximum temperature required by the design.

[0034] The storage tank gas cavity assembly, liquid cavity assembly and management device are mostly made of titanium alloy, aluminum alloy and stainless steel material. The traditional process method is to complete the welding of the product by electron beam welding at one time. During welding, the electron beam current acts on the center of the management device rib, as shown in Figure 2 . In order to achieve reliable connection of the three, the weld penetration, weld width and metal melting amount are required to be large, so that the problem of excessive welding heat is prone to exist. In addition, when the product is welded by using this process, pores and un-melted welding defects are prone to exist in the weld, and the weld appearance is as shown in Figure 3 .

[0035] In order to solve the problems existing in the traditional welding process of the storage tank, the present application proposes a three-in-one structure defect-free connection method for the storage tank, and the welding schematic diagram is as shown in Figure 4 . After completing the positioning welding of the storage tank gas cavity assembly, liquid cavity assembly and management device, the electron beam current acts on the two butt joints respectively, forming a double-channel welding seam microscopically, ensuring that the defect nucleation site and the overflow channel are completely consistent during welding, avoiding the generation of pores in the weld, and at the same time reducing the strict requirements of the three-in-one weld on the weld appearance. The double-channel welding seam appearance is as shown in Figure 5 .

[0036] The specific method comprises the following steps:

[0037] Before welding the product, a welding test piece needs to be processed first. The test piece is composed of three parts, which respectively simulate the three-in-one welding part air cavity assembly, liquid cavity assembly and management device structure. When the weld diameter is not greater than 100 mm, a ring-shaped part is generally used to simulate the part, the diameter of which is completely consistent with that of the product, and the thickness of the air cavity assembly simulation part and the liquid cavity assembly simulation part is completely consistent with that of the product. The width, height and thickness of the management device simulation part are completely the same as those of the product. When the weld diameter is greater than 100 mm, a flat plate of the same material can be used to simulate each part, and the wall thickness, rib width and lock bottom thickness are required to be consistent with those of the product. The width of the flat plate simulation part is generally not less than 50 mm, and the length is not less than 100 mm.

[0038] After the processing of the test piece is completed, the test piece is cleaned and assembled and welded. The welding method is electron beam welding, and the assembly gap of the test piece is not greater than 0.1 mm. After assembly is completed, the minimum distance between the storage tank half membrane and the weld is measured, and temperature test paper is attached to the position equidistant from the weld to measure the temperature. Thermocouple or infrared temperature measurement method can also be used to measure the highest temperature of the part during the welding of the test piece.

[0039] During welding, positioning welding of the three parts is first carried out by using electron beam welding process. During positioning welding, the electron beam current acts on the center of the management device rib, and the electron beam current is 8-15 mA. After positioning, the electron gun is placed at the abutting surface between the air cavity assembly simulation part and the management device simulation part to weld the air cavity assembly simulation part and the management device simulation part. The acceleration voltage is 40-150 KV, the vacuum degree of the vacuum chamber is 100-10-2 Pa, the welding speed is 0.5-4 m / min, and the welding current is 8-20 mA. The welding current is determined according to the wall thickness of the test piece, and the weld penetration is required to be greater than 0.5-1.5 mm of the wall thickness of the air cavity assembly. The welding working distance is 50-1000 mm, and the specific welding height is determined according to the clamping position of the product. After 10-25 min, the electron beam gun is placed at the abutting surface between the liquid cavity assembly simulation part and the management device simulation part to weld the test piece, and the welding parameters are the same as those for welding the air cavity assembly simulation part.

[0040] After the welding of the test piece is completed, the peak temperature of the temperature measurement part is checked to be not greater than 120℃ or the highest temperature required by the design technical conditions. After confirmation of qualification, a metallographic sample is cut from the stable area of the weld to detect the weld penetration and the fusion width of the root of the management device. The weld penetration is required to be greater than 0.5-2.5 mm of the wall thickness of the air and liquid cavity shell, and the fusion width is required to be greater than 0.5-3 mm of the rib width of the management device. At the same time, the internal quality of the weld is detected, and the weld is required to be free of any welding defects. After detection is qualified, the welding parameters used for welding are selected as the selected welding parameters for formal welding.

[0041] The gas cavity assembly, liquid cavity assembly, and management device to be welded are cleaned and assembled; during cleaning, the oxide film on the surface of the parts within 10 mm of the weld area is completely removed, and the cleaning method can use manual scraping, chemical pickling, or laser cleaning. After cleaning, the storage tank is assembled, and the assembly gap of the parts is required to be no more than 0.1 mm. If the gap cannot be guaranteed, the parts can be assembled by pressing with a press, and after pressing, the product is positioned by argon arc welding. The argon arc welding current is 25-35 A, and a point is positioned every 100-150 mm. For parts with a large gap, the number of positioning welds can be appropriately increased.

[0042] After assembly is completed, all protective caps are removed to ensure that the inner cavity of the storage tank is normally evacuated. In order to reduce the conduction of welding heat to the half membrane, a special welding tool is used to clamp the product on the rotary table of the electron beam welding machine. The welding tool is composed of a red copper holding ring and an aluminum alloy connecting device, as shown in Figure 6 The red copper holding ring is provided at a distance of 3-40 mm from the weld, and the thickness of the red copper holding ring is 3-10 mm. The red copper holding ring has a two-half-ring structure, and the profile of the two-half-ring structure is the same as the profile of the product. The two-half-ring structure is reliably fixed to a specific position of the product to ensure good adhesion to the product. After adhesion, the overall gap is no more than 0.1 mm, and the maximum local gap is no more than 0.2 mm, so as to ensure that as much welding heat as possible is conducted to the red copper holding ring. The aluminum alloy connecting device is required to reliably connect the product to the rotary table of the electron beam welding machine. The connection between the connecting device and one side of the rotary table of the electron beam welding machine is reliably connected by bolts and a pressing plate. The connecting device and the product are in contact with each other through the same profile. The side in contact with the product is a hemisphere with the same profile as the product. The effective contact between the connecting device and the product is achieved by axially pressing the product. When the product is assembled, temperature measurement test paper is pasted at equidistant positions of the half membrane.

[0043] After the storage tank product is clamped, the three-in-one structure is welded. In order to prevent the welding heat from causing thermal damage to the half membrane of the management device, the three products are welded by using a segmented welding process based on the selected welding parameters. Each segment has a length of 100-250 mm, and the welding length is determined according to the requirement that the temperature of the half membrane part does not exceed the maximum design temperature. After completing the positioning and welding of one segment, the product is turned 180°, and the next segment is welded until all the welds are welded.

[0044] After the product is welded, the three-in-one weld is subjected to X-ray inspection, and the weld quality is required to meet the GJB1718A-2005 I-level weld requirement. After the welding of a batch of storage tank products is completed and the relevant inspection tests of the products are qualified, one product is subjected to a blasting test, and the blasting position is required to be located away from the weld and the heat affected zone.

[0045] Example 1:

[0046] A certain rubber-plastic composite semi-membrane tank is welded by a gas cavity assembly, a liquid cavity assembly and a management device, and the three parts are made of TC4 titanium alloy. The thickness of the welding part of the gas cavity assembly and the liquid cavity assembly is 2 mm, the height of the rib of the management device is 2 mm, the width of the rib is 0.5 mm, and the thickness of the lock bottom is 1.5 mm. The highest temperature allowed to be borne by the non-metallic semi-membrane assembled on the management device at a position 11.5 mm away from the welding seam is 120℃. It is required to realize reliable connection of the gas cavity assembly, the liquid cavity assembly and the management device by using a welding process, and the tank is divided into two cavities of the gas cavity and the liquid cavity by the management device after welding, and there should be no any cross-communication. The welding seam grade should reach the requirement of I-grade welding seam, and the burst pressure of the product should be not less than 9.5 MPa.

[0047] First, a TC4 titanium alloy welding test piece is processed, the test piece has a structure as shown in Figure 2 The thickness of the gas cavity assembly and the liquid cavity assembly simulation piece is 2 mm, and the length and width size specification is 200 mm x 100 mm. The width of the rib of the management device simulation piece is 0.5 mm, the height of the rib is 2 mm, and the thickness of the lock bottom is 1.5 mm, and all the sizes are consistent with the product.

[0048] After the processing of the test piece is completed, the test piece is cleaned by pickling, and then the test piece is assembled and welded. First, 10 mA electron beam current is used for positioning welding of the test piece, and the positioning welding is performed on the center of the 0.5 mm wide rib of the management device simulation piece by the electron beam current. After welding, the electron gun is offset by 0.25 mm after 10 min, the welding of the liquid cavity assembly and the management device is realized, the electron beam current is 17 mA, and after 15 min after welding, the electron beam is offset by 0.5 mm, and the welding of the gas cavity assembly and the management device is also realized by using 17 mA. After welding, the welding seam is cut and inspected, the weld penetration is 2.8 mm, the fusion width of the lock bottom part is 1.2 mm, the welding seam has no defects, and the highest temperature at a position 11.5 mm away from the welding seam is 75-80℃.

[0049] After the product is cleaned and assembled, the welding parameters of the test piece are used for welding of the product, and the product is welded in four sections according to the size of the product. After welding, the welding seam is silver-white, the welding seam is subjected to X-ray detection, the welding seam quality meets the requirement of GJB1718A-2005 I grade, and the product is qualified after one-time welding. The tank is subjected to air tightness test and semi-membrane turnover emptying test, and the test results are stable. The product is subjected to burst test, the burst pressure is 13.7 MPa, the damage position is a non-welding position of the shell, and the product quality is qualified.

[0050] The above-described embodiments are only the preferred specific embodiments of the present application, and the usual changes and replacements made by those skilled in the art within the technical solution range of the present application should be included in the protection scope of the present application.

Claims

1. A method for defect-free joining of a tank three-in-one structure, characterized by, The method comprises the following steps: Assembling the gas cavity assembly simulation piece, the liquid cavity assembly simulation piece and the management device simulation piece, carrying out double-pass welding on the three-in-one structure formed after the assembly, carrying out electron beam welding on the butt joint surface of the gas cavity assembly simulation piece and the management device simulation piece and the butt joint surface of the liquid cavity assembly simulation piece and the management device simulation piece respectively, and obtaining a storage tank test piece; detecting whether the welding seam and the temperature of the test piece during the welding process meet the design requirements, and using the welding parameters used during the welding as the selected welding parameters if the requirements are met; Cleaning and assembling the gas cavity assembly product, the liquid cavity assembly product and the management device product, and carrying out double-pass welding on the three-in-one structure formed after the assembly by using a segmented welding process based on the selected welding parameters; and carrying out X-ray inspection on the welding seam after the welding of the product is completed; Before the double-pass welding, a special welding tool is used to assist the double-pass welding, and the special welding tool comprises a purple copper holding ring and an aluminum alloy connecting structure. The purple copper holding ring is arranged at a welding area 3-40 mm away from the welding seam.

2. A method of defect-free joining of a tank three-in-one structure according to claim 1, characterized in that, The double-pass welding on the three-in-one structure formed after the assembly comprises the following steps: Measuring the minimum distance between the plastic half membrane of the management device simulation piece and the welding seam, and placing a temperature measuring device at a position equidistant from the welding seam to measure the temperature during the welding process; The interval between the two welding passes in double-pass welding is 10-25 minutes. The welding parameters are: accelerating voltage of 40-150 kV, and vacuum level of 10 kV in the vacuum chamber. 0 ~10 -2 Pa, welding speed is 0.5~4m / min, welding current is 8~20mA.

3. A method of defect-free joining of a tank three-in-one structure according to claim 2, characterized in that, Detecting whether the temperature of the test piece and the welding seam during the welding process meet the design requirements, comprising the following steps: According to the temperature value measured by the temperature measuring device, the peak temperature is required to be less than the maximum temperature required by the design; Carrying out section inspection on the welding seam to check the weld penetration, the fusion width of the root of the management device test piece and the internal quality of the welding seam, and the design requirements are that the weld penetration is greater than 0.5-2.5 mm of the wall thickness of the gas cavity assembly simulation piece shell, greater than 0.5-2.5 mm of the wall thickness of the liquid cavity assembly simulation piece shell, greater than 0.5-3 mm of the width of the management device simulation piece rib, and the welding seam is free of welding defects.

4. The method of claim 1, wherein the method is a method of defect-free joining of a tank three-in-one structure, characterized by, Firstly, the three-in-one structure formed after the assembly is subjected to positioning welding, and then the double-pass welding is carried out after 5-15 min; the positioning welding is carried out by using electron beam welding, and the electron beam current acts on the center of the management device rib, and the welding current is 8-15 mA.

5. The method of claim 1, wherein the method is a method of defect-free joining of a tank three-in-one structure, characterized by, The gas cavity assembly simulation piece, the liquid cavity assembly simulation piece and the management device simulation piece are assembled, and the assembly gap between the simulation pieces is not greater than 0.1 mm.

6. The method of claim 1, wherein the method is a method of defect-free joining of a tank three-in-one structure, characterized by, The three products are welded by using a segmented welding process based on the selected welding parameters, the welding of each segment is completed, the product is turned by 180°, the next segment is welded, and the welding of all the welding seams is completed; wherein, the length of each segment is determined according to the condition that the temperature of the plastic half membrane of the management device product does not exceed the maximum temperature required by the design.

7. The method of claim 6, wherein the method further comprises: The length of each segment is 100-250 mm.

8. The method of claim 1, wherein the method is a method of defect-free joining of a tank three-in-one structure, characterized by, The processing gas cavity assembly simulation piece, the liquid cavity assembly simulation piece, the management device simulation piece, when the weld diameter is not greater than 100 mm, the three simulation pieces are all ring piece simulation pieces, the diameter is consistent with the product to be welded, and the gas cavity assembly simulation piece, the liquid cavity assembly simulation piece and the corresponding product thickness are consistent, the management device simulation piece rib width, rib height and lock bottom thickness are completely same with the product; when the weld diameter is greater than 100 mm, the same material flat plate is used to simulate each product to be welded, the wall thickness of the gas cavity assembly simulation piece and the liquid cavity assembly simulation piece, the rib width and the lock bottom thickness of the management device simulation piece are consistent with the corresponding product, the width of each simulation piece is not less than 50 mm, and the length is not less than 100 mm.

9. The method of claim 1, wherein the method is a method of defect-free joining of a tank three-in-one structure, characterized by, The gas cavity assembly product to be welded, the liquid cavity assembly product, the management device product are cleaned, and the oxide film on the surface of the product within 10 mm of the weld area is removed during cleaning.

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