Welding gun offset distance determining method and welding method for metal plate welding case lock bottom welding seam

Abstract

The invention discloses a method for determining the offset distance of a welding gun of a metal plate welding case lock bottom welding seam and a welding method, and belongs to the technical field of fusion welding technologies. The method for determining the offset distance of the welding gun comprises the steps that the machining side welding thickness L1, the metal plate side welding thickness L2 and the bottom locking thickness L3 of the metal plate welding case are obtained, and the axis offset P of a welding gun tungsten electrode and the center of a welding connector is calculated; based on the axis offset P, the opposite position of a welding gun tungsten electrode is determined, the offset angle theta over a welding bead and the diameter phi A of the welding bead are obtained, and the offset distance L between the opposite position of the welding gun tungsten electrode and the position over the welding bead is calculated; and based on the axis offset P of the welding gun tungsten electrode and the center of the welding joint and the offset distance L between the position right opposite to the welding gun tungsten electrode and the position right above the welding bead, the alignment position line of the tip end of the welding gun tungsten electrode is determined at the workpiece welding joint. The welding method comprises the steps that the position of the circumferential automatic welding gun mechanism is adjusted based on the alignment position line, and a welding gun is located in the welding bead upslope direction in the circumferential direction.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fusion welding, and relates to a method for determining the offset distance of a welding gun for welding a bottom seam of a sheet metal welding case and a welding method. BACKGROUND

[0002] As the "skeleton" of an engine, a case is a key component for bearing force, pressure and temperature and for containment, and bears various alternating stress loads, temperature loads and aerodynamic loads. As an important component of a case, a sheet metal welding case has the advantages of low production cost, short development cycle, light weight and fast repair, and thus plays an irreplaceable role in engine design. High-precision and low-stress welding of a sheet metal welding case is a key core technology for guaranteeing the life and reliability of a high-performance engine from a compressor component to a tail nozzle component. In the design of an engine case, specific structures are required at specific positions, and a cavity type sheet metal welding case is a common case structure. Considering performance reliability and manufacturing process, the welding joint of this type of cavity type sheet metal welding case is often designed as a non-equal-thickness joint with a bottom lock.

[0003] At this time, the method of welding at the center and directly above the welding bead by using a conventional tungsten electrode pair causes the phenomenon of molten pool offset due to the different heat dissipation performances of the two sides of the joint during welding. The sheet metal part has poor heat dissipation and fast melting speed, and thus has more molten metal. The other side has good heat dissipation and slow melting speed, and thus has less molten metal. The phenomenon of molten pool offset occurs in the weld, which causes the root of the bottom lock to not be completely melted or to form a cavity, and stress concentration occurs, which easily causes cracks and greatly reduces the fatigue life of the component. SUMMARY

[0004] The present application aims to solve the technical problem of the phenomenon of molten pool offset in the weld by using the conventional method of welding at the center and directly above the welding bead by using a conventional tungsten electrode pair, and provides a method for determining the offset distance of a welding gun for welding a bottom seam of a sheet metal welding case and a welding method.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, the present application discloses a method for determining the offset distance of a welding gun for welding a bottom seam of a sheet metal welding case, comprising: obtaining the machining side welding thickness L1, the sheet metal side welding thickness L2 and the bottom lock thickness L3 of the sheet metal welding case, and calculating the axis offset P of the tungsten electrode of the welding gun from the center of the welding joint; determining the directly opposite position of the tungsten electrode of the welding gun based on the axis offset P, obtaining the offset angle θ and the welding bead diameter ΦA directly above the welding bead, and calculating the offset distance L of the directly opposite position of the tungsten electrode of the welding gun from the welding bead directly above; based on the axis offset P of the tungsten electrode of the welding gun from the center of the welding joint and the offset distance L of the directly opposite position of the tungsten electrode of the welding gun from the welding bead directly above, determining the alignment position line of the tip of the tungsten electrode of the welding gun at the welding joint of the workpiece.

[0006] Further improvement lies in that: The offset P of the tungsten electrode of the welding torch from the axis of the center of the welding joint is specifically calculated as: P = L1 - L2 + ½L3.

[0007] The offset distance L of the position of the tungsten electrode of the welding torch from the position directly above the weld is specifically calculated as: L = ΦA x sin(½θ).

[0008] The empirical value of the offset angle θ of the position of the tungsten electrode of the welding torch from the position directly above the weld is 5°-7°, and is positively correlated with the protruding height h of the weld relative to the base surface.

[0009] In a second aspect, the present application discloses a welding method for the bottom weld of a case lock of a sheet metal welding machine based on the welding torch offset distance determination method, which comprises the following steps: Based on the position adjustment of the alignment line, the welding torch mechanism is automatically adjusted in the circumferential direction, and the welding torch is in the uphill direction of the weld in the circumferential direction; Based on the principle of magnetic field contraction of high-frequency pulse generated arc, the combination parameters of high-frequency pulse and precision pulse are determined; The welding is completed in four passes according to the process of uniform positioning welding, dense welding points, base welding and cover welding.

[0010] The determination of the combination parameters of high-frequency pulse and precision pulse is specifically as follows: The working mode is high-frequency pulse superimposed precision pulse mode; the high-frequency pulse frequency is set to the maximum frequency of the equipment; the peak value time and the base value time of the precision pulse are set to the same time; the peak current, the base current and the high-frequency pulse current are set to a preset ratio.

[0011] The preset ratio of the peak current, the base current and the high-frequency pulse current is 5:2:3.

[0012] Argon is used as the protective gas in the welding process, the protective gas flow is 8-12 L / min during the uniform positioning welding and the dense welding points, and the protective gas flow is increased to 15-20 L / min during the base welding and the cover welding.

[0013] After the base welding is completed, the defect detection of the root of the weld is performed by using the penetration detection method, and the detection qualified standard is that the diameter of a single pore is not more than 0.3 mm, and the number of pores in the 100 mm length weld is not more than 3, and the cover welding is performed after the detection is qualified.

[0014] The base welding adopts narrow groove welding, and the weld width is controlled to be 4-6 mm, the weld width of the cover welding is 1.5-2 times of the weld width of the base welding, and a 0.5-1 mm excess height is reserved during the cover welding.

[0015] Compared with the prior art, the present application has the following beneficial effects: The present application discloses a method for determining the offset distance of a welding gun for a lock bottom weld of a sheet metal welding machine, which precisely matches the non-equal thickness structural characteristics of the lock bottom joint, quantifies the machining side welding thickness L1, the sheet metal side welding thickness L2 and the lock bottom thickness L3, and scientifically calculates the axis offset P, thereby solving the problem of molten pool offset caused by the difference in heat dissipation on both sides of the joint in conventional centering welding, ensuring that the lock bottom root can be fully melted, effectively avoiding welding defects such as incomplete fusion and cavities, and significantly improving the weld forming quality. The offset distance L is calculated in combination with the offset angle θ above the weld and the weld diameter ΦA, realizing multi-dimensional accurate positioning of the tungsten electrode of the welding gun in the correct position, rather than single-dimensional offset adjustment, so that the tungsten tip can accurately align with the key fusion area of the lock bottom weld, ensuring uniform distribution of the weld metal at the lock bottom structure, reducing stress concentration, reducing the risk of crack generation, and thereby improving the fatigue life and structural reliability of the sheet metal welding machine. Through the coordinated calculation of the axis offset P and the offset distance L, the alignment position line of the tungsten tip of the welding gun is determined, providing accurate positioning basis for subsequent automated welding, avoiding subjective errors of manual adjustment, ensuring the consistency and stability of the welding gun position during welding, especially suitable for batch production scenarios of circular automatic welding, improving the repeatability and controllability of the welding process. The determination method is directly derived based on the structural parameters of the lock bottom weld of the sheet metal welding machine, without relying on complex trial and error tests or experience value estimation, simplifying the adjustment process of the welding gun offset distance, shortening the process preparation period, reducing the dependence on the skill level of the operator, and improving both production efficiency and welding quality, providing technical support for efficient and high-quality manufacturing of sheet metal welding machines. The method constructs a standardized welding gun positioning logic through quantified parameters, which can flexibly adjust the offset and offset distance according to the lock bottom thickness, welding thickness and other structural parameters of sheet metal welding machines of different specifications, adapt to the welding needs of sheet metal welding machines of various types of cavities, improve the universality and adaptability of the technical scheme, and reduce the process switching cost when producing multiple specifications of products.

[0016] The application discloses a welding method for a bottom weld of a box lock of a sheet welding machine, adjusts a welding gun position with a reference to a positioning line, and clearly sets the welding gun in a circumferential direction to be in a slope direction of a welding bead, which accurately matches the heat dissipation difference characteristics of the non-equal thickness structure of the bottom joint. Compared with the pool offset problem caused by the conventional central welding, the positioning mode can guide the arc energy to be accurately distributed to the side with good heat dissipation and slow melting speed, ensure that the bottom root of the lock is provided with sufficient fusion energy, effectively avoid fatal defects such as incomplete fusion and root cavity, reduce the stress concentration phenomenon, reduce the crack generation tendency from the welding source, and significantly improve the mechanical properties and fatigue life of the weld, thereby providing a core guarantee for the pressure bearing and force bearing stability of the sheet welding machine box. The method is based on the high-frequency pulse magnetic field contraction arc principle, adopts a combination parameter mode of high-frequency pulse and precision pulse, and has obvious advantages compared with single pulse or conventional direct current welding. The magnetic field generated by the high-frequency pulse can effectively contract the arc, improve the arc stiffness and energy density, make the energy distribution of the arc on the non-equal thickness joint more uniform, and avoid problems such as excessive melting and welding beads of the sheet metal side due to poor heat dissipation; the precision pulse can accurately control the heating and cooling rhythm of the molten pool, promote the gas in the molten pool to fully escape, reduce the gas hole defects, simultaneously refine the weld grain, and improve the density and toughness of the weld. The synergistic effect of the two kinds of pulses makes the weld forming more beautiful and the size precision higher, and meets the technical requirements of high-precision welding of the sheet welding machine box. The method adopts a four-pass welding process of "uniform distribution positioning welding-encryption welding point-bottom welding-covering welding", and forms a systematic guarantee system from temporary fixing to permanent forming. The uniform distribution positioning welding can accurately fix each part of the sheet welding machine box, avoid position deviation caused by thermal deformation during welding, further strengthen the temporary connection strength, provide a stable structure foundation for subsequent continuous welding, and reduce the welding deformation; the bottom welding, as the "skeleton" of the weld, can rely on accurate welding gun positioning and optimized pulse parameters to ensure that the bottom root of the lock is completely fused and a reliable bearing foundation is built; the covering welding can make up for the small defects on the surface of the bottom welding, improve the surface quality and corrosion resistance of the weld. The four-step process is closely linked, so that the connection strength and sealing performance of the weld meet the standards, and the method is suitable for severe working conditions such as alternating stress and high temperature in the engine. The method clearly adopts a circumferential automatic welding gun mechanism, and takes the accurate positioning line as the adjustment reference, thereby breaking away from the dependence on manual welding experience, and making the welding gun position adjustment more standardized. The automatic operation not only greatly improves the welding efficiency, but also can shorten the single piece welding time by more than 30% compared with manual welding, and can ensure that the welding gun position and welding parameters of each weld are highly consistent in batch production, thereby avoiding individual differences caused by manual operation. Meanwhile, the standardized pulse parameter setting and welding process can be easily integrated into the automatic control system of the production line, realize the full-process automation from the welding gun positioning to the completion of the welding, reduce the skill threshold and labor intensity of the operator, and provide a feasible path for batch and efficient production of the sheet welding machine box.To sum up, the present application actively offsets the tungsten electrode of the welding torch by adjusting the P value, can offset the difference in heat dissipation on both sides of the joint, eliminate weld offset, ensure the lock bottom melting, avoid stress concentration, prolong the fatigue life; the welding torch tungsten electrode is opposite to the welding direction on the slope, which can increase the flowability of the molten pool metal along the welded weld, reduce the front width of the weld, increase the protrusion height of the weld relative to the substrate surface, and realize the active control of the front excess height of the weld by adjusting the size of theta value; by designing reasonable high-frequency pulse and precise pulse combination parameters and welding process, the heat input can be reduced, the weld penetration can be increased, the welding deformation can be reduced, the titanium alloy weld porosity can be eliminated, and the appearance size and morphology uniformity of the weld can be improved.

[0017] Further, the preset ratio of the peak current, the base current and the high-frequency pulse current is 5:2:3, which is optimized for precise matching of "sufficient penetration-stable arc-uniform energy": the peak current has the highest proportion, which can ensure sufficient root fusion of the lock bottom; the base current has a moderate proportion, which can avoid arc extinction during welding; the high-frequency pulse current has a reasonable proportion, which can effectively shrink the arc and optimize the molten pool shape.

[0018] Further, argon is used as the protective gas, argon has stable chemical properties, can form a dense protective atmosphere in the weld area, effectively isolate air oxygen, nitrogen and other impurities, avoid defects such as oxidation and nitriding of the weld, and ensure the purity and corrosion resistance of the weld, adapt to the high temperature and high pressure working environment of the engine.

[0019] Further, the penetration detection process is added after the backing welding is completed, which can timely find potential defects such as incomplete fusion and porosity at the root of the weld, avoid covering the defects after the surface welding, cause subsequent repair, control the weld quality from the source, and reduce the rework cost and use risk. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments, it should be understood that the following drawings only show some embodiments of the present application, therefore should not be regarded as a limitation on the scope, for those skilled in the art, without creative labor, other related drawings can also be obtained from these drawings.

[0021] Figure 1 The schematic diagram of the lock bottom welding joint and the weld in the welding method of the lock bottom weld of the sheet welding machine case in the embodiment of the present application; Figure 2 The schematic diagram of the weld pool and the morphology control in the welding method of the lock bottom weld of the sheet welding machine case in the embodiment of the present application; Figure 1 The enlarged view of A in the embodiment of the present application; Figure 3 The schematic diagram of the weld pool and the morphology control in the welding method of the lock bottom weld of the sheet welding machine case in the embodiment of the present application; Figure 4 Figure 1 is a schematic diagram of arc contraction in a welding method for welding a bottom weld joint of a case lock according to an embodiment of the present application; Figure 5 Figure 2 is a schematic diagram of weld joint and heat affected zone width in a welding method for welding a bottom weld joint of a case lock according to an embodiment of the present application.

[0022] Wherein: 1-case body; 2-metal sheet forming part; 3-weld joint; 4-heat affected zone; 5-circumferential weld bead; 6-tungsten electrode of welding gun; 11-filler platform; 12-joint bottom lock; 13-root of joint bottom lock; P-axis offset amount of tungsten electrode and joint center; h-protrusion height of weld joint relative to base surface; L-offset distance of tungsten electrode opposite position and weld bead directly above; θ-offset angle of tungsten electrode opposite position and weld bead directly above; I-welding current; ΦA-weld bead diameter; B-magnetic field generated by high frequency pulse; H1-weld joint width; H2-heat affected zone width; L1-welding thickness on case side; L2-welding thickness on metal sheet side; L3-bottom lock thickness. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0025] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0026] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used for differentiation and cannot be understood as indicating or implying relative importance.

[0027] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0028] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] The present application will be described in further detail below in conjunction with the accompanying drawings: Referring to Figure 1 , Figure 2 and Figure 3 , the embodiment of the present application discloses a method for determining the offset distance of the welding gun of the bottom weld of the cabinet lock of the sheet metal welding machine, comprising: Step one, obtaining the machining side welding thickness L1, sheet metal side welding thickness L2 and lock bottom thickness L3 of the sheet metal welding machine cabinet, and calculating the axis offset amount P of the welding gun tungsten electrode and the center of the welding joint; The calculation of the axis offset amount P of the welding gun tungsten electrode and the center of the welding joint is specifically: P = L1 - L2 + ½L3.

[0030] The offset distance L of the welding gun tungsten electrode directly opposite position and the welding bead directly above is specifically: L = ΦA x sin(½θ).

[0031] The empirical value of the offset angle θ of the welding gun tungsten electrode directly opposite position and the welding bead directly above is 5°-7°, and is positively correlated with the protrusion height h of the welding seam relative to the base surface.

[0032] Step two, determine the tungsten electrode alignment position of the welding gun based on the axis offset P, and obtain the offset angle θ and the weld diameter ΦA above the weld, and calculate the offset distance L between the tungsten electrode alignment position of the welding gun and the weld above. Step three, based on the axis offset P between the tungsten electrode of the welding gun and the center of the welding joint and the offset distance L between the tungsten electrode alignment position of the welding gun and the weld above, determine the alignment position line of the tungsten electrode tip of the welding gun at the welding joint of the workpiece.

[0033] The present application discloses a kind of welding gun offset distance determination method of welding seam of sheet metal welding machine box lock bottom, accurately match lock bottom joint non-equal thickness structural characteristics, by quantifying machining side welding thickness L1, sheet metal side welding thickness L2 And lock bottom thickness L3, scientific calculation axis offset P, from the root, solve the pool offset problem caused by the difference of joint two sides heat dissipation of conventional centering welding, Ensure that lock bottom root can be fully melted, effectively avoid unmelted, void and other welding defects, significantly improve the quality of weld formation.Combined with the offset angle θ above the weld and the weld diameter ΦA, the offset distance L is calculated, and multi-dimensional accurate positioning of the tungsten electrode alignment position of the welding gun is realized, rather than single-dimensional offset adjustment, so that the tungsten electrode tip can accurately align the key fusion area of the lock bottom weld, ensure that the weld metal is evenly distributed at the lock bottom structure, reduce stress concentration phenomenon, reduce the risk of crack generation, and thus improve the fatigue life and structural reliability of sheet metal welding machine box.Through the collaborative calculation of axis offset P and offset distance L, the alignment position line of the tungsten electrode tip of the welding gun is clear, which provides accurate positioning basis for subsequent automatic welding, avoids subjective error of manual adjustment, ensures consistency and stability of welding gun position during welding, especially suitable for batch production scene of circular automatic welding, improves repeatability and controllability of welding process.The determination method is directly derived based on the structural parameters of the lock bottom weld of the sheet metal welding machine box, without relying on complex trial and error or experience value estimation, simplifying the adjustment process of the welding gun offset distance, shortening the process preparation period, reducing the dependence on the skill level of operators, and improving production efficiency and welding quality.The method constructs a standardized welding gun positioning logic by quantifying parameters, which can flexibly adjust the offset and offset distance according to the lock bottom thickness, welding thickness and other structural parameters of different specifications of sheet metal welding machine box, adapt to the welding needs of various types of cavity sheet metal welding machine box, improve the universality and adaptability of the technical scheme, and reduce the process switching cost when producing multiple specifications of products.

[0034] Referring to Figure 4 and Figure 5 The present application also discloses a welding method for the lock bottom weld of the sheet metal welding machine box, comprising: Step one, adjust the position of the circular automatic welding gun mechanism based on the alignment position line, and the welding gun is in the uphill direction of the weld in the circumferential direction. Step two, based on the principle of arc contraction of high-frequency pulse generated magnetic field, determine the combination parameters of high-frequency pulse and precision pulse; The working mode is high-frequency pulse superimposed precision pulse mode; the high-frequency pulse frequency is set to the maximum frequency of the equipment; the peak time and the base time of the precision pulse are set to the same time; the peak current, the base current and the high-frequency pulse current are set to a preset ratio. The preset ratio of the peak current, the base current and the high-frequency pulse current is 5:2:3.

[0035] Step three, complete the welding in four passes according to the process of uniform positioning welding, encryption welding, base welding and cover welding.

[0036] The welding process uses argon as a protective gas, the protective gas flow is 8-12L / min during uniform positioning welding and encryption welding, and the protective gas flow is increased to 15-20L / min during base welding and cover welding. After the base welding is completed, the root of the weld is detected for defects by using the penetration detection method, and the detection qualified standard is that the diameter of a single pore is not more than 0.3mm, and the number of pores in the 100mm length weld is not more than 3, and after the detection is qualified, the cover welding is carried out. The base welding adopts narrow groove welding method, and the weld width is controlled to be 4-6mm, the weld width of the cover welding is 1.5-2 times of the base welding weld width, and 0.5-1mm of excess height is reserved during the cover welding.

[0037] The application discloses a welding method for a bottom weld of a box lock of a sheet welding machine, adjusts a welding gun position with a reference to a positioning line, and clearly sets the welding gun in a circumferential direction to be in a slope direction of a welding bead, which accurately matches the heat dissipation difference characteristics of the non-equal thickness structure of the bottom joint. Compared with the pool offset problem caused by the conventional central welding, the positioning mode can guide the arc energy to be accurately distributed to the side with good heat dissipation and slow melting speed, ensure that the bottom root of the lock is provided with sufficient fusion energy, effectively avoid fatal defects such as incomplete fusion and root cavity, reduce the stress concentration phenomenon, reduce the crack generation tendency from the welding source, and significantly improve the mechanical properties and fatigue life of the weld, thereby providing a core guarantee for the pressure bearing and force bearing stability of the sheet welding machine box. The method is based on the high-frequency pulse magnetic field contraction arc principle, adopts a combination parameter mode of high-frequency pulse and precision pulse, and has obvious advantages compared with single pulse or conventional direct current welding. The magnetic field generated by the high-frequency pulse can effectively contract the arc, improve the arc stiffness and energy density, make the energy distribution of the arc on the non-equal thickness joint more uniform, and avoid problems such as excessive melting and welding beads of the sheet metal side due to poor heat dissipation; the precision pulse can accurately control the heating and cooling rhythm of the molten pool, promote the gas in the molten pool to fully escape, reduce the gas hole defects, simultaneously refine the weld grain, and improve the density and toughness of the weld. The synergistic effect of the two kinds of pulses makes the weld forming more beautiful and the size precision higher, and meets the technical requirements of high-precision welding of the sheet welding machine box. The method adopts a four-pass welding process of "uniform distribution positioning welding-encryption welding point-bottom welding-covering welding", and forms a systematic guarantee system from temporary fixing to permanent forming. The uniform distribution positioning welding can accurately fix each part of the sheet welding machine box, avoid position deviation caused by thermal deformation during welding, further strengthen the temporary connection strength, provide a stable structure foundation for subsequent continuous welding, and reduce the welding deformation; the bottom welding, as the "skeleton" of the weld, can rely on accurate welding gun positioning and optimized pulse parameters to ensure that the bottom root of the lock is completely fused and a reliable bearing foundation is built; the covering welding can make up for the small defects on the surface of the bottom welding, improve the surface quality and corrosion resistance of the weld. The four-step process is closely linked, so that the connection strength and sealing performance of the weld meet the standards, and the method is suitable for severe working conditions such as alternating stress and high temperature in the engine. The method clearly adopts a circumferential automatic welding gun mechanism, and takes the accurate positioning line as the adjustment reference, thereby breaking away from the dependence on manual welding experience, and making the welding gun position adjustment more standardized. The automatic operation not only greatly improves the welding efficiency, but also can shorten the single piece welding time by more than 30% compared with manual welding, and can ensure that the welding gun position and welding parameters of each weld are highly consistent in batch production, thereby avoiding individual differences caused by manual operation. Meanwhile, the standardized pulse parameter setting and welding process can be easily integrated into the automatic control system of the production line, realize the full-process automation from the welding gun positioning to the completion of the welding, reduce the skill threshold and labor intensity of the operator, and provide a feasible path for batch and efficient production of the sheet welding machine box.In summary, the present application actively offsets the tungsten electrode shaft by adjusting the P value, which can offset the difference in heat dissipation on both sides of the joint, eliminate weld offset, ensure the lock bottom melting, avoid stress concentration, prolong the fatigue life; the tungsten electrode of the welding torch is opposite to the uphill direction of the weld, which can increase the flowability of the molten pool metal along the welded weld, reduce the front width of the weld, increase the protrusion height of the weld relative to the substrate surface, and actively control the front excess height of the weld by adjusting the size of the theta value; by designing reasonable high-frequency pulse and precise pulse combination parameters and welding process flow, the heat input can be reduced, the weld penetration can be increased, the welding deformation can be reduced, the titanium alloy weld porosity can be eliminated, and the appearance size and morphology uniformity of the weld can be improved.

[0038] Example 1 (1) Take L1, L2, L3 as an example, measure the actual size of the workpiece to be welded, calculate the axial offset P of the tungsten electrode and the center of the joint according to the three sizes, and the empirical value is P = L1-L2+½L3. Figure 1

[0039] (2) As shown in the figure, the arrow direction is the uphill direction of the weld. Measure the weld diameter ΦA, and according to ΦA and θ value, calculate the offset distance L of the tungsten electrode opposite position and the weld directly above, L = ΦA×sin(½θ), wherein θ is the offset angle of the tungsten electrode opposite position and the weld directly above, and the empirical value is 5°-7°. The greater the protrusion height h of the weld relative to the substrate surface, the greater θ. Figure 2 (3) According to the axial offset P of the tungsten electrode and the center of the joint and the offset distance L of the tungsten electrode opposite position and the weld directly above calculated in steps (1) and (2), draw the tungsten electrode tip alignment line at the assembled workpiece welding joint.

[0040] (4) Adjust the circular automatic welding torch mechanism, and align the tungsten electrode of the welding torch according to the step (3) workpiece joint line position. Among them, circumferentially, the welding torch is in the uphill direction of the weld.

[0041] (5) Design high-frequency pulse and precise pulse combination parameters, and the working mode is high-frequency pulse superimposed precise pulse mode, the high-frequency pulse frequency is 20000Hz, the precise pulse peak time and the base value time are both 0.5s, and the precise pulse frequency is 1Hz. Main current (peak value): auxiliary current (base value): high-frequency pulse current = 3:2:1.

[0042] (6) According to the uniform positioning welding→densification welding point→bottom welding→cover welding process, weld for 4 times, and check the appearance morphology and size of the weld protrusion height.

[0043]

[0044] ​​A certain titanium alloy cavity case of a certain engine is taken as an example. The case is a cavity type welded whole case. The main body is made of α + β titanium alloy TC25 forged body and 1.8 mm, 1.5 mm thick α titanium alloy TA15 sheet metal curved shell welded by 4 argon arc welding seams. The lock bottom thickness is 1.5 mm ~ 2.0 mm, the width is 0.8 mm ~ 1.2 mm, the weld level is I level, and the product drawing requires that the weld should have a protrusion, and the protruding part is between 0.15 mm ~ 0.8 mm. Since the case is a cavity structure, the joint assembly gap and the misalignment amount are difficult to control, the back of the joint has a lock edge stop, and the weld penetration of the weld cannot be observed. A method based on high frequency pulse superimposed precision pulse current contraction arc is used to realize the active control of the cavity type sheet welding case lock bottom ring weld pool and appearance. The steps are as follows: 1. Take one of the welds as an example. The actual sizes of L1, L2 and L3 are 2.5 mm, 1.8 mm and 1.4 mm respectively. The axial offset of the tungsten electrode and the joint center is P = L1-L2+½L3 = 1.4 mm. 2. The weld diameter ΦA is 562 mm, and θ is 6°. The offset distance L between the tungsten electrode and the weld above is L = ΦA×sin(½θ)=29.4 mm. 3. According to the axial offset of the tungsten electrode and the joint center calculated in steps 1 and 2, the offset distance of the tungsten electrode and the weld above is 29.4 mm. The tungsten electrode tip alignment line is drawn on the assembled workpiece welding joint. 4. Adjust the circular automatic welding torch mechanism, and align the tungsten electrode according to the workpiece joint line position. Among them, in the circumferential direction, the welding torch is in the uphill direction of the weld. 5. Design the high frequency pulse and precision pulse combination parameters. The working mode is high frequency pulse superimposed precision pulse mode. The high frequency pulse frequency is designed as 20000 Hz. The peak value time and the base value time of the precision pulse are both 0.5 s. The main current (peak value), the auxiliary current (base value) and the high frequency pulse current are 120 A, 80 A and 40 A respectively according to the ratio of 3:2:1. 6. According to the uniform positioning welding → dense welding point → bottom welding → surface welding process, the welding is carried out for 4 times. Then check whether the weld protrusion height meets the requirements of 0.15 mm ~ 0.8 mm, and check the compliance of the rest of the appearance and size according to the corresponding standard.

[0045] By adjusting the P value and actively offsetting, the method can offset the heat dissipation difference on both sides of the joint, eliminate the weld offset, ensure the lock bottom melting, avoid stress concentration, increase the weld pool metal flowability along the welded weld direction by aligning the welding torch tungsten electrode with the uphill direction of the weld, reduce the weld front width, increase the weld protrusion height relative to the base surface, and reduce the heat input by designing reasonable high frequency pulse and precision pulse combination parameters and welding process, increase the weld penetration, reduce the welding deformation, eliminate the titanium alloy weld pore residue, and improve the weld appearance size and uniformity.

[0046] The working process of the present application is as follows: The purpose of the present application is to provide a method for active control of the cavity type panel welding machine case lock bottom ring weld pool and appearance based on high frequency pulse superimposed precision pulse current arc contraction, tungsten electrode circumferential and axial offset, thereby realizing the cavity type panel welding machine case lock bottom ring weld pool and appearance. (1) With Figure 1 and Figure 2 as an example, the actual size of the workpiece to be welded L1, L2, L3 is measured, and the axial offset P of the tungsten electrode from the center of the joint is calculated according to the three sizes, with an empirical value of P = L1 - L2 + ½L3.

[0047] (2) Figure 3 As shown in the figure, the arrow direction is the uphill direction of the weld. Measure the weld diameter ΦA, and according to ΦA and θ value, calculate the offset distance L of the tungsten electrode directly opposite position from the directly above weld, L = ΦA × sin(½θ), where θ is the offset angle of the tungsten electrode directly opposite position from the directly above weld, with an empirical value of 5°-7°, and the greater the protrusion height h of the weld relative to the base surface, the greater the θ.

[0048] (3) According to the axial offset P of the tungsten electrode from the center of the joint and the offset distance L of the tungsten electrode directly opposite position from the directly above weld calculated in steps (1) and (2), draw the tungsten electrode tip alignment line at the assembled workpiece welding joint.

[0049] (4) Adjust the circumferential automatic welding torch mechanism, and align the welding torch according to the workpiece joint line position in step (3). Among them, circumferentially, the welding torch is in the uphill direction of the weld.

[0050] (5) Using the magnetic field contraction arc principle of high frequency pulse, design the high frequency pulse and precision pulse combination parameters, with a working mode of high frequency pulse superimposed precision pulse mode, the high frequency pulse frequency is designed as the maximum frequency of the equipment, the precision pulse peak time and base time are designed as the same time. The main current (peak value), secondary current (base value) and high frequency pulse current are designed in a certain proportion.

[0051] (6) Weld according to the uniform positioning welding→densification welding→base welding→cover welding process for 4 times, and check the weld protrusion height and other appearance and size.

[0052] The present application can offset the heat dissipation difference on both sides of the joint by actively adjusting the P value of the tungsten electrode of the welding gun, can eliminate the weld offset, can ensure the lock bottom melting, can avoid the stress concentration, can prolong the fatigue life, can increase the flowability of the molten pool metal along the welded weld direction by adjusting the θ value of the tungsten electrode of the welding gun, can reduce the front width of the weld, can increase the protrusion height of the weld relative to the substrate surface, and can realize the active control of the front excess height of the weld by adjusting the size of the θ value.

[0053] The above is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for determining the welding torch offset distance of the bottom weld seam in a sheet metal welding machine casing, characterized in that, include: Obtain the machining side welding thickness L1, sheet metal side welding thickness L2, and bottom locking thickness L3 of the sheet metal welding casing, and calculate the axial offset P between the tungsten electrode of the welding torch and the center of the welding joint. Based on the axial offset P, determine the position of the tungsten electrode of the welding torch, obtain the offset angle θ and weld diameter ΦA directly above the weld bead, and calculate the offset distance L between the position of the tungsten electrode of the welding torch and the position directly above the weld bead. Based on the axial offset P between the tungsten electrode of the welding torch and the center of the weld joint, and the offset distance L between the tungsten electrode of the welding torch facing the weld bead and directly above it, the alignment line of the tip of the tungsten electrode of the welding torch is determined at the weld joint of the workpiece.

2. The method for determining the welding torch offset distance of the bottom weld seam of a sheet metal welding machine casing according to claim 1, characterized in that, The calculation of the axial offset P between the tungsten electrode of the welding torch and the center of the weld joint is specifically as follows: P = L1 - L2 + ½L3.

3. The method for determining the welding torch offset distance of the bottom weld seam of a sheet metal welding machine casing according to claim 1, characterized in that, The specific calculation of the offset distance L between the tungsten electrode of the welding torch and the weld bead is as follows: L = ΦA × sin(½θ).

4. The method for determining the welding torch offset distance of the bottom weld seam of a sheet metal welding machine casing according to claim 1, characterized in that, The empirical value of the offset angle θ between the tungsten electrode of the welding torch and the weld bead is 5° to 7°, which is positively correlated with the height h of the weld bead relative to the substrate surface.

5. A welding method for the bottom lock weld of a sheet metal welding machine casing based on the welding torch offset distance determination method according to any one of claims 1-4, characterized in that, include: Based on the position adjustment of the circumferential automatic welding torch mechanism according to the alignment line, the welding torch is in the uphill direction of the weld bead in the circumferential direction. Based on the principle of magnetic field contraction arc generated by high-frequency pulses, the parameters of high-frequency pulses and precision pulse combinations are determined. The welding process is completed in four steps: uniform positioning welding, denser welding points, root pass welding, and cover pass welding.

6. The welding method for the bottom lock weld of the sheet metal casing according to claim 5, characterized in that, The specific steps for determining the combination parameters of high-frequency pulses and precision pulses are as follows: The operating mode is a high-frequency pulse superposition precision pulse mode; the high-frequency pulse frequency is set to the maximum frequency of the equipment; the peak time and base time of the precision pulse are set to be the same. The peak current, base current, and high-frequency pulse current are set to preset ratios.

7. The welding method for the bottom lock weld of the sheet metal casing according to claim 6, characterized in that, The preset ratio of the peak current, base current, and high-frequency pulse current is 5:2:

3.

8. The welding method for the bottom lock weld of the sheet metal casing according to claim 5, characterized in that, Argon is used as the shielding gas in the welding process. The shielding gas flow rate is 8-12 L / min when the welding points are evenly distributed and densely packed, and the shielding gas flow rate is increased to 15-20 L / min when the welding is root pass and cover pass.

9. The welding method for the bottom lock weld of the sheet metal casing according to claim 5, characterized in that, After the root pass welding is completed, the root of the weld is inspected for defects using a penetrant testing method. The inspection pass criteria are: the diameter of a single pore does not exceed 0.3 mm, and the number of pores in a 100 mm weld length does not exceed 3. After passing the inspection, the cover pass welding is performed.

10. The welding method for the bottom lock weld of the sheet metal casing according to claim 5, characterized in that, The root pass welding adopts a narrow pass welding method, with the weld width controlled at 4-6mm. The weld width of the cover pass welding is 1.5-2 times the width of the root pass weld, and a 0.5-1mm excess height is reserved during the cover pass welding.

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