Manufacturing system and method for efficient electric arc-friction stir machining additive

Abstract

The invention discloses a manufacturing system and method for an efficient electric arc-stirring friction machining additive, and relates to the technical field of welding additive manufacturing. The manufacturing system comprises a control device, a stirring friction machining device, an efficient electric arc device and an ultrasonic device, has unique advantages on machining of a large-scale engineering sample piece to be subjected to material increase, effectively solves the problem that a large number of air holes exist in common electric arc material increase manufacturing, and avoids the influence that the performance becomes poor due to increase of heat input. The manufacturing system is low in cost, production line copying is convenient, the automatic additive manufacturing process can be achieved, and the modern industrial production requirement is met. And single-system control is adopted, the manufacturing process method is simple, the problems that the electric arc additive quality stability is poor and the large component additive efficiency is low are solved, and the high-quality and high-efficiency additive manufacturing process of the large component is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of welding additive manufacturing, and in particular to a high-efficiency arc-friction stir processing additive manufacturing system and method. Background Art

[0002] Solid-phase additive manufacturing technology has unique advantages in the additive manufacturing of alloy components, but it is still in the laboratory research stage due to the low additive efficiency and the difficulty and poor stability of continuous additive feeding. Porosity is inevitable in the arc additive manufacturing process, so pulsed additive manufacturing is often used. Thanks to the stirring effect of the pulsed arc on the molten pool, it helps to eliminate pores and other welding defects. For pores in the welding / additive process, the molten pool action time is generally changed to reduce the amount of pores by reducing the welding / additive speed and increasing the welding / additive line energy. However, at this time, the welding / additive heat input increases, which will increase the welding / additive deformation and internal stress. Therefore, a solution is needed to improve efficiency while reducing the pore size and avoiding the impact of increased heat input on performance degradation.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention includes providing a high-efficiency arc-friction stir processing additive manufacturing system and method, which can stably control the additive quality, improve the level of automation, significantly improve the pore size of additive manufacturing, and improve the additive efficiency and quality.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, an embodiment of the present invention provides a high-efficiency arc-friction stir processing additive manufacturing system, which includes a control device, a friction stir processing device, a high-efficiency arc device, and an ultrasonic device;

[0007] The control device controls the high-efficiency arc device to perform additive manufacturing; the control device controls the friction stir processing device to perform friction stir processing;

[0008] The ultrasonic device is arranged between the friction stir processing device and the high-efficiency arc device, and is close to the friction stir processing device; the ultrasonic device and the friction stir processing device are movably connected; the control device controls the ultrasonic device to assist in additive manufacturing;

[0009] The relative distance between the high-efficiency arc device and the friction stir processing device is ≤200mm.

[0010] In an optional embodiment of the present invention, the high-efficiency arc device is a shunt plasma high-efficiency arc device, which includes a main power supply, an auxiliary power supply, a shunt plasma high-efficiency arc welding gun, a pulse current control mechanism, an additive base plate and a current sensor; the shunt plasma high-efficiency arc welding gun includes a wire feeder, a water-cooled copper sleeve, an annular plasma electrode, and a shunt plasma additive manufacturing arc system;

[0011] The positive electrode of the main power supply is connected to the wire feeder, and the negative electrode is connected to the sample to be added, and the main arc is formed by the shunt plasma additive manufacturing arc system; the positive electrode of the auxiliary power supply is connected to the wire feeder, and the negative electrode is connected to the water-cooled copper sleeve, and the bypass arc is formed after being connected through the annular plasma electrode and the bypass shunt arc; the bypass arc and the main arc are coupled together to form a composite arc;

[0012] The pulse current control mechanism coordinates the control of the bypass current and the main current, and includes a pulse signal controller and a pulse signal processor; the pulse signal processor detects the main current pulse signal of the current sensor, and when it is detected that the main current is at the pulse base value, the pulse signal controller is triggered to adjust the bypass current to the pulse base value to ensure the stability of the composite arc during welding; when it is detected that the main current pulse is at a peak value, the pulse signal controller is triggered to adjust the bypass current pulse to a peak value to ensure lower workpiece heat input during welding.

[0013] In an optional embodiment of the present invention, the split-flow plasma high-efficiency arc welding gun further includes an insulating porcelain sleeve, a conductive nozzle, a protective gas hood, a plasma confinement nozzle and a welding wire.

[0014] In an optional embodiment of the present invention, the control device includes a processing power supply and a welding power supply; wherein the processing power supply is connected to the friction stir processing device, and the welding power supply is connected to the high-efficiency arc device.

[0015] In an optional embodiment of the present invention, the friction stir processing device comprises a detachably connected processing spindle and a processing tool, wherein the processing spindle is connected to a processing power source, and the processing tool is in contact with the additive material during the friction stir processing;

[0016] A fixing fixture is arranged on one side of the machining spindle close to the machining tool.

[0017] In an optional embodiment of the present invention, the ultrasonic device comprises an ultrasonic probe and a slide rail that are slidably connected, wherein the ultrasonic probe contacts the additive material during friction stir processing;

[0018] The ultrasonic device is movably connected to a fixing fixture on the processing spindle.

[0019] In a second aspect, an embodiment of the present invention provides a method for processing additive materials using the aforementioned manufacturing system, the method comprising the following steps:

[0020] (1) Grind the surface of the base plate and the additive parts of the sample to be added, and perform tooling according to the requirements of additive manufacturing;

[0021] (2) Starting the ultrasonic device and the high-efficiency arc device to realize the ultrasonic-assisted high-efficiency arc additive manufacturing process in the initial stage;

[0022] After the processing tool of the friction stir processing device reaches the specified position, the processing power supply is started to simultaneously realize ultrasonic-assisted high-efficiency arc additive manufacturing and friction stir processing;

[0023] (3) After completing one layer of additive manufacturing, the step (2) is repeated to continue the additive manufacturing;

[0024] (4) After the additive manufacturing is completed, the high-efficiency arc device is turned off first, and then the stir friction processing device and the ultrasonic device are turned off to complete the additive manufacturing of the sample to be added.

[0025] In an optional embodiment of the present invention, during the additive manufacturing process, the welding wire is stretched by 10mm-13mm, the wire feeding speed is 5m / min-10m / min, the additive speed is 0.3m / min-0.5m / min, the length of each stacking layer is 220mm-5000mm, and the height of the additive workpiece is 5mm-450mm when the stacking is completed.

[0026] In an optional embodiment of the present invention, the rotation speed during the friction stir processing is 800rpm-1500rpm, the travel speed is 0.1m / min-0.3m / min, and the pressing depth is 0.5mm-1.5mm;

[0027] The diameter of the stirring head shoulder of the processing tool is 8mm-12mm, the length of the stirring needle is 1.3mm-2.7mm, and the diameter of the stirring needle is 1.5-2.5mm.

[0028] In an optional embodiment of the present invention, the additive manufacturing method used is unidirectional additive; argon is used as the protective gas during the additive manufacturing process, and the flow rate of the protective gas is 8L / min-25L / min.

[0029] The beneficial effects of the embodiments of the present invention include:

[0030] The high-efficiency arc-friction stir processing additive manufacturing system and method provided in the embodiments of the present invention adopt a high-efficiency arc additive device and a coordinated control method of main and bypass pulses to improve the additive efficiency while reducing the heat input of the sample to be added, thereby realizing a stable and reliable split-flow plasma high-efficiency arc additive manufacturing process; adopting an ultrasonic-assisted method, while stabilizing the arc additive manufacturing process, the quality and efficiency of the stir friction processing are improved, and it has unique advantages for the processing of samples to be added in large-scale projects, and is more suitable for process production; in addition, it effectively solves the problem of many pores in ordinary arc additive manufacturing and the characteristic of insufficient rigidity of robot stir friction processing, thereby completing the stable control of the additive manufacturing process.

[0031] The manufacturing system provided by the present invention has low device cost, is easy to replicate on the production line, can realize an automated additive manufacturing process, and meets the needs of modern industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a schematic diagram of the structure of a high-efficiency arc-friction stir processing additive manufacturing system;

[0034] Figure 2 It is a schematic diagram of the structure of a split-flow plasma high-efficiency arc device;

[0035] Figure 3 Schematic diagram of coordinated control of main and bypass current pulse signals;

[0036] Figure 4 This is a microscopic pore structure morphology diagram of additive manufacturing in the first embodiment;

[0037] Figure 5 This is the microscopic pore structure morphology of the additively manufactured first comparison sample.

[0038] Icons: 100-manufacturing system; 101-control device; 102-processing power supply; 103-welding power supply; 200-friction stir processing device; 201-processing spindle; 202-processing tool; 203-fixed fixture; 300-ultrasonic device; 301-steering fixture; 302-ultrasonic probe; 303-slide rail; 400-high-efficiency arc device; 401-divided plasma high-efficiency arc welding gun; 402-divided plasma high-efficiency arc device; 403-additive sample; 404-base plate of sample to be added; 405 - welding wire; 406- wire feeder; 407- insulating porcelain sleeve; 408- conductive nozzle; 409- water-cooled copper sleeve; 410- protective gas hood; 411- plasma restraint nozzle; 412- annular plasma electrode; 413- bypass shunt arc; 414- composite arc; 415- main arc; 416- shunt plasma additive manufacturing arc system; 500- main power supply; 600- auxiliary power supply; 700- pulse current control mechanism; 701- pulse signal processor; 702- pulse signal controller; 800- current sensor. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0042] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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 a limitation on the present invention.

[0043] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0044] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0045] The impact of pores on welds / additive manufacturing has been reported in many studies. Large pores are obviously not as dense as small pores, and are more likely to affect the strength, toughness, fatigue life, densification, mechanical strength and thermal conductivity of the product. Therefore, the optimization of welding / additive processes should be developed in the direction of reducing and eliminating pores and defects and improving the quality of samples.

[0046] Patent CN201921712815.7 introduces a composite welding system of arc welding and friction stir processing, which can realize additive and processing processes simultaneously. However, the patent first relies on a robotic arm to realize additive and processing. For larger samples 403 to be additive, the rigidity of the system cannot guarantee the stable processing process; secondly, in the context of high-quality and efficient manufacturing, ordinary arc additives are difficult to guarantee efficiency and quality requirements; finally, in the process of additive and processing synchronization, welding defects are not solved in time, resulting in uncontrollable welding quality during welding, affecting the quality after welding, and lack of auxiliary means to ensure the quality of the intermediate welding process.

[0047] The overall structure, working principle and technical effects of the device provided by the present invention and the detailed steps, implementation principle and technical effects of the supporting method are described in detail below through embodiments and in conjunction with the accompanying drawings.

[0048] First embodiment

[0049] The embodiment of the present invention provides a high-efficiency arc-friction stir processing additive manufacturing method. The structural schematic diagram of the high-efficiency arc-friction stir processing additive manufacturing system 100 used by the method is shown in FIG. Figure 1 , wherein the manufacturing system 100 includes a control device 101, a stir friction processing device 200, a high-efficiency arc device 400 and an ultrasonic device 300.

[0050] It should be noted that the manufacturing system 100 provided by the present invention is suitable for additive manufacturing of large and small types of samples 403 to be added, and has special advantages in particular for additive manufacturing of large samples 403 to be added.

[0051] Before additive manufacturing, the surface of the sample base plate 404 and the additive parts to be added need to be polished, and then tooling is performed according to the additive manufacturing requirements. Among them, polishing is the default processing before additive manufacturing, and no polishing is performed during the additive manufacturing process.

[0052] The sample 403 to be added in this embodiment uses 2219-T87 aluminum alloy as a substrate, the size of the substrate is 260mm×200mm×10mm, and the raw material is ER2319 (diameter 1.2mm) aluminum alloy welding wire 405. In other embodiments of the present invention, the material, size of the substrate and the material of the welding wire 405 can be reasonably adjusted and replaced according to the actual needs of additive manufacturing.

[0053] It should be noted that during the production and transportation of welding wire 405 and substrate, due to the influence of moisture and pollution, the surface may be stained with impurities such as moisture, dust or grease, which will increase the risk of porosity defects and brittle fracture during additive manufacturing and welding. Therefore, after removing the surface oxide scale and contaminants before use, it is necessary to dry the surface contaminated impurities to ensure the quality of additive manufacturing and welding.

[0054] The control device 101 includes a processing power supply 102 and a welding power supply 103; wherein the processing power supply 102 is connected to the friction stir processing device 200 to control it to perform friction stir processing; the welding power supply 103 is connected to the high-efficiency arc device 400 to control it to perform additive manufacturing.

[0055] Please refer to Figure 2 The high-efficiency arc device 400 is a shunt plasma high-efficiency arc device 402, which includes a main power supply 500, an auxiliary power supply 600, a shunt plasma high-efficiency arc welding gun 401, a pulse current control mechanism 700, an additive base plate and a current sensor 800; the shunt plasma high-efficiency arc welding gun 401 includes a wire feeder 406, a water-cooled copper sleeve 409, an annular plasma electrode 412, a shunt plasma additive manufacturing arc system 416 and a bypass shunt arc 413.

[0056] It should be noted that the plasma arc is an arc formed by strongly compressing the arc column of the free arc through external restraint. The temperature of the plasma welding arc is higher than that of the general arc, and the energy density is large. It is an efficient arc welding method. At a large current, it can achieve stable large droplet transition and deep penetration. Bypass shunting is an important process for efficient arc welding. By controlling the main current unchanged, the bypass shunting method is adopted to reduce the welding current of the parent material, reduce the welding heat input, and improve the welding efficiency.

[0057] The split-flow plasma high-efficiency arc welding torch 401 further includes an insulating porcelain sleeve 407 , a conductive nozzle 408 , a protective gas hood 410 , a plasma confinement nozzle 411 and a welding wire 405 .

[0058] Among them, the insulating porcelain sleeve 407 can play a role in protecting the electrode, preventing the arc from directly burning the electrode, thereby extending the service life of the electrode. The conductive nozzle 408 is a conductive element of the welding arc or plasma, which has the characteristics of guiding the welding wire 405, maintaining the stability of the arc and controlling the flow of plasma gas flow. The protective gas hood 410 protects the arc, the electrode and the welded parts by providing a gas medium to the arc space to prevent them from being eroded by the atmosphere. The plasma confinement nozzle 411 quickly cools down the high temperature generated during the welding process through the internally circulating cooling water to protect itself from being melted; at the same time, the special structural design of the plasma confinement nozzle 411 makes the arc subject to a certain degree of confinement when passing through, thereby changing the shape and stability of the arc.

[0059] The positive pole of the main power supply 500 is connected to the wire feeder 406, and the negative pole is connected to the sample to be added 403, and the main arc 415 is formed by the shunt plasma additive manufacturing arc system 416; the positive pole of the auxiliary power supply 600 is connected to the wire feeder 406, and the negative pole is connected to the water-cooled copper sleeve 409, and the bypass arc 413 is connected through the annular plasma electrode 412 to form a bypass arc; the bypass arc and the main arc 415 are coupled together to form a composite arc 414.

[0060] It should be noted that the pulse current frequency is controlled during additive manufacturing to complete a stable additive manufacturing process; during additive manufacturing, the shunt plasma additive manufacturing arc system 416 uses the bypass shunt arc 413 to complete the shunt effect, reduce the current acting on the workpiece, and at the same time couple with the main arc 415 to form a composite arc 414, completing a high-efficiency, low-heat input additive manufacturing process.

[0061] The pulse frequency is very small compared to the ultrasonic frequency. Generally, the pulse frequency is between 20Hz-100Hz. The ultrasonic frequency of the equipment used is 15kHz-40kHz, which can achieve automatic frequency tracking, that is, the frequency is adjusted according to the processing tool holder pressure. The amplitude of the ultrasonic equipment is 2μm-20μm and can be adjusted steplessly. The synergy mechanism is that a stable arc additive process is achieved when the pulses are coordinated. After the ultrasound is applied, the ultrasound mainly acts on the stir friction processing area, and it also has a beneficial effect on the arc additive area.

[0062] The pulse current control mechanism 700 coordinates and controls the bypass current and the main current, and includes a pulse signal controller 702 and a pulse signal processor 701; the pulse signal processor 701 detects the main current pulse signal of the current sensor 800, and when it is detected that the main current is at the pulse base value, the pulse signal controller 702 is triggered to adjust the bypass current to the pulse base value to ensure the stability of the composite arc 414 during welding; when it is detected that the main current pulse is at the peak value, the pulse signal controller 702 is triggered to adjust the bypass current pulse to the peak value to ensure lower workpiece heat input during welding. The schematic diagram of the coordinated control of the main and bypass current pulse signals is shown in FIG. Figure 3 .

[0063] It should be noted that in this embodiment, a shunt high-efficiency arc additive device is used, and pulse coordination controls the high-efficiency arc to achieve stable control of the quality in the additive manufacturing process. When the main current is the pulse peak value, the bypass current is the pulse peak value. At this time, the current reduction effect to be inspected by the welder can be guaranteed to be the most obvious, which can reduce the heat input of the workpiece, thereby reducing welding deformation and internal stress, expanding the welding process window, and improving welding quality; when the main current is the pulse base value, the bypass current is the pulse base value, which plays a good role in stabilizing the arc and ensuring the stability of welding.

[0064] For example, in the high-efficiency arc aluminum alloy additive manufacturing process, the main current is 80A-180A, the bypass current is 20A-80A, the current voltage is positively correlated with the wire feeding speed, and the high efficiency is reflected before the bypass current is applied. If the arc additive manufacturing process can be realized at 140A, after the bypass current is applied, the main current can be set to 180A and the bypass current to 40A. At this time, the additive manufacturing current is still 140A, but after the main current increases, the wire feeding speed is accelerated, the deposited metal per unit time increases, and the welding speed increases while maintaining consistent forming, thereby improving the additive manufacturing efficiency.

[0065] In addition, in the present embodiment, the relative distance between the high-efficiency arc device 400 and the friction stir processing device 200 is set to be ≤200 mm. The main consideration is the intensity of the improvement effect on the arc additive effect when the same ultrasonic energy field is applied to the middle position of the additively manufactured workpiece. The ultrasonic effect is mainly to improve the processing process. Beyond a certain range, the effect of ultrasound applied to the arc molten pool will become weak, and the improvement effect on the arc additive will be small.

[0066] In this embodiment, the relative distance between the high-efficiency arc device 400 and the friction stir processing device 200 is set to 150 mm. In other embodiments of the present invention, the relative distance can be reasonably adjusted according to actual needs.

[0067] At the beginning of additive manufacturing, the control device 101 is used to control the ultrasonic device 300 and the split plasma high-efficiency arc welding gun 401 to complete the high-efficiency arc additive manufacturing process, coordinate the control of the pulse current control system and the ultrasonic device 300 to complete a stable ultrasonic-assisted high-efficiency additive process, regulate the organization of the additive and after the additive, and preliminarily improve the welding porosity problem.

[0068] It should be noted that in the process of high-efficiency arc additive manufacturing, by adjusting the pulse frequency and improving the pulse stirring effect, the pore discharge is initially promoted and the pore problem is improved. At the same time, due to the influence of ultrasonic action, the metal wettability and solidification effect are improved, and the weld structure is improved. After high-efficiency arc additive manufacturing, ultrasonic-assisted friction stir processing can further improve the internal pores and structure of post-arc additive manufacturing, transform coarse dendrites into fine equiaxed crystals, increase density, and at the same time break up and discharge pores, reduce pore diameter, apply additive compressive stress, improve the stress state of the additive part, and improve additive performance.

[0069] In the process of efficient arc additive manufacturing, this embodiment first adjusts the pulse frequency to complete a stable additive manufacturing process, and then adjusts the ultrasonic frequency to ensure that the two do not cancel each other out, thereby ensuring the beneficial effects of ultrasonic frequency and pulse additive manufacturing.

[0070] In this embodiment, argon is used as the shielding gas during the additive manufacturing process, and the shielding gas flow rate is 25 L / min.

[0071] When performing additive manufacturing, a unidirectional additive method was selected, the dry extension length of welding wire 405 was 12 mm, the wire feeding speed was 8 m / min, the length of each stacking layer was 240 mm, the height of the additive workpiece was 45 mm when the stacking was completed, and the additive speed was 0.35 m / min for composite additive manufacturing;

[0072] When the additive manufacturing is completed, the high-efficiency arc device 400 is turned off first, and then the stir friction processing device 200 and the ultrasonic control device 101 are turned off to complete the additive manufacturing process of the sample 403 to be added.

[0073] The ultrasonic device 300 includes a slidably connected ultrasonic probe 302 and a slide rail 303 , wherein the ultrasonic probe 302 is in contact with the additive material during the friction stir processing; the ultrasonic device 300 is movably connected to the fixing fixture 203 on the processing spindle 201 .

[0074] Specifically, the ultrasonic probe 302 is fixedly connected to the ultrasonic device 300 through the slide rail 303, and the ultrasonic device 300 is fixedly connected to the rigid fixing fixture 203 on the processing spindle 201 through the steering fixture 301, and additive manufacturing is performed on the base plate 404 of the sample to be added, completing the high-quality manufacturing process of the additive component. In this embodiment, there is no special limitation on the fixing method of the steering fixture 301 and the fixing fixture 203, which can be reasonably selected according to actual needs.

[0075] The ultrasonic device 300 is arranged between the friction stir processing device 200 and the high-efficiency arc device 400, and is close to the friction stir processing device 200, for assisting additive manufacturing. The ultrasonic device 300 is started at the beginning of the high-efficiency arc additive manufacturing and stopped at the end of the friction stir processing, running through the entire additive manufacturing process, and the frequency is controllable. After applying the ultrasonic effect, the friction stir processing process is completed under the dual effects of acoustic softening and promoting flow.

[0076] It should be noted that the control device 101 is used to turn on the ultrasonic device 300 and the high-efficiency arc device 400, and an ultrasonic-assisted high-efficiency arc additive manufacturing process is implemented in the initial stage.

[0077] The ultrasonic-assisted method is adopted to stabilize the arc additive manufacturing process while improving the quality and efficiency of the stir friction processing, which is more suitable for process production. Among them, the placement angle of the ultrasonic device 300 and the stir friction processing device 200, as well as the specific position of the ultrasonic probe 302, are reasonably adjusted to the steering fixture 301 according to actual needs to ensure that the ultrasonic probe 302 is in contact with the additive during the stir friction processing.

[0078] It should be noted that ultrasound, as a mechanical wave, first produces a mechanical effect on the arc welding melt, and the stirring of the molten pool is helpful for the discharge of pores, improves the wettability of the molten pool, and improves the quality of additives; in addition, part of the ultrasonic energy will be converted into heat energy and absorbed by the melt, improving the solidification and forming of the additive process, refining the organization, and improving the performance. Under the action of ultrasound, it is helpful to remove gas and impurities, and the pores in the molten pool are easier to merge and grow and discharge the molten pool. In terms of additive organization, coarse dendrites are produced in the process of high-efficiency arc additive. Under the action of ultrasound, some of the coarse dendrites will become non-dendritic organizations with smaller diameters, and the stir friction processing process will become equiaxed crystal organization due to the dynamic recrystallization process. The inventors also found that the smaller the initial grain size, the smaller the size of the fine equiaxed crystals formed after stir friction processing, and the higher the hardness; therefore, the additive sample 403 manufactured by the ultrasonic device 300 assisted by the stir friction processing device 200 will have better density and higher performance. The application of ultrasound mainly affects the friction stir processing part, which plays a preliminary role in improving the efficient arc additive manufacturing process.

[0079] In this embodiment, the ultrasonic device 300 is connected to the friction stir processing device 200, which has the following characteristics:

[0080] (1) Ultrasonic friction reduction effect: Ultrasonic vibration improves the fluidity of the material, reduces the friction shear stress between the stirring head and the surface of the additive sample 403, and plays an ultrasonic friction reduction role; the acoustic stress promotes dislocation movement, reduces the interface plastic shear force, and plays an ultrasonic softening role.

[0081] (2) Ultrasonic sono-softening mechanism, specifically refers to: after applying the ultrasonic energy field during the friction stir processing, the rheological stress of the metal is reduced, and the acoustic energy is preferentially absorbed by the lattice defects, reducing the shear stress and significantly softening the metal material without the need for significant heating. For 2xxx series aluminum alloys, the inventors found that the ultrasonic energy field can reduce the axial pressure by 4%-7% and the spindle torque by 4%-8%, and the lower the heat input, the more obvious the effect. This is obviously more in line with the high-efficiency and low-heat additive manufacturing process, avoiding high-power processing of equipment under high pressure and high torque, reducing energy consumption during the friction stir processing, and conforming to the concept of green, economical and sustainable industrial development.

[0082] The welding pressure of the stir friction processing is reduced, which can reduce the surface roughness of the sample 403 to be added, improve the weld formation, and provide a welding process window. For aluminum alloys, the processing speed can be increased after applying ultrasound, and the processing efficiency can be improved. For example, for 7N01-T4 aluminum alloy, before the ultrasonic energy field is applied, defects such as tunnels and "S" line defects appear at a processing speed of 200mm / min; after the ultrasonic energy field is applied, the processing speed can be increased to 300mm / min without defects, which expands the process window and improves the processing efficiency.

[0083] (3) Ultrasonic delay effect: after the stirring head completes the stirring of the weld metal, the ultrasonic effect still promotes the movement of dislocations without causing the increase of new dislocations, thereby accelerating the growth of grains, which is the ultrasonic delay effect. Under the action of ultrasound, the grain size in the stirring zone increases, and at the same time, the ratio of large and small angle grain boundaries is differentiated into two levels, which is attributed to the superposition effect of the delay effect of the ultrasonic energy field and the promotion of recrystallization.

[0084] The friction stir processing device 200 includes a detachably connected processing spindle 201 and a processing tool 202, wherein the processing spindle 201 is connected to a processing power source 102, and the processing tool 202 is in contact with the additive during the friction stir processing; a fixing fixture 203 is provided on the side of the processing spindle 201 close to the processing tool 202; the fixing fixture 203 can be movably connected to the ultrasonic device 300.

[0085] In the present embodiment, a gantry-type friction stir processing apparatus 200 is used. In other embodiments of the present invention, a friction stir processing apparatus 200 of other specifications and brands can be selected according to actual needs.

[0086] It should be noted that the fixing fixture 203 is made of a rigid material and is fixedly connected to the machining spindle 201 to prevent the ultrasonic probe 302 or the slide rail 303 from falling off due to excessive frequency when the ultrasonic device 300 is working, thereby affecting the quality of the final additive material, affecting the additive material efficiency, causing material waste and increasing cost investment. In this embodiment, there is no particular limitation on the fixing method of the fixing fixture 203 on the machining spindle 201, and it can be reasonably selected according to actual needs, such as threaded connection, welding connection, etc.

[0087] The processing tool 202 includes a stirring head and a stirring needle. In this embodiment, the stirring head shoulder diameter is 10 mm, the stirring needle length is 2.0 mm, and the stirring needle diameter is 2.0 mm. In other embodiments of the present invention, the relevant dimensions of the processing tool 202 can be reasonably adjusted according to the actual manufacturing dimensions of the additive.

[0088] The rotation speed of the stir friction processing process is 1200rpm, the travel speed is 0.2m / min, and the pressing depth is 1.0mm; it is related to the specifications of the sample 403 to be added and the thickness of each layer of addition; in other embodiments of the present invention, reasonable adjustments can be made according to actual needs.

[0089] After the processing tool 202 arrives at the processing position, the control device 101 controls the processing power supply 102 to work, and the stir friction processing tool 202 starts to perform the processing task. The distance between the ultrasonic probe 302 and the stir friction processing tool 202 is adjusted by the slide rail 303. After the ultrasonic effect is applied, under the dual effects of sonic softening and promoting flow, the stir friction processing process is completed, and efficient arc additive manufacturing and stir friction processing are simultaneously realized.

[0090] The microscopic pore structure morphology of the additive manufacturing in this embodiment is shown in Figure 4 ,from Figure 4 It can be seen that the pores on the surface of the additive are evenly distributed and their size is greatly reduced. This inventive method can reduce the aluminum alloy arc additive manufacturing system 100, improve the additive manufacturing quality, and is suitable for the additive manufacturing process of large components.

[0091] Please refer to Figure 1 and Figure 2 The specific process of the ultrasonic-assisted high-efficiency arc-friction stir processing additive manufacturing system 100 in this embodiment for additive manufacturing is as follows:

[0092] (1) ER2319 (diameter 1.2 mm) aluminum alloy welding wire 405 is used as raw material, 2219-T87 aluminum alloy is used as substrate, and the substrate size is 260 mm × 200 mm × 10 mm.

[0093] It should be noted that the surface oxide scale and contaminants of welding wire 405 and substrate were removed and dried before use; argon was used as the shielding gas during the test, and the shielding gas flow rate was 25L / min.

[0094] (2) When additive manufacturing begins, the control device 101 is used to control the ultrasonic device 300 and the split plasma high-efficiency arc welding gun 401 to complete the high-efficiency arc additive manufacturing process, and coordinate the control Figure 2 Medium pulse current control mechanism 700 and Figure 1 The ultrasonic device 300 completes a stable ultrasonic-assisted efficient material addition process, regulates the structure of the material addition and the material addition, and preliminarily improves the welding porosity problem;

[0095] After the processing tool 202 in the friction stir processing device 200 reaches the processing position, the control device 101 controls the processing power supply 102 to work, and the processing tool 202 starts to perform the processing task. The relative distance between the ultrasonic probe 302 and the processing tool 202 is adjusted to 50 mm through the slide rail 303. After applying the ultrasonic effect, the friction stir processing step is completed under the dual effects of sonic softening and promoting flow.

[0096] It should be noted that when performing composite additive manufacturing, a unidirectional additive method is selected, and the specific process parameters are as follows: the dry extension length of welding wire 405 is 12 mm, the wire feeding speed is 8 m / min, the additive speed is 0.35 m / min, the length of each stacking layer is 240 mm, and the height of the additive workpiece is 45 mm when the stacking is completed.

[0097] The diameter of the stirring head shoulder is 10 mm, the stirring needle is 2.0 mm long, and the stirring needle diameter is 2.0 mm. The rotation speed of the friction stir processing process is 1200 rpm, the travel speed is 0.2 m / min, and the pressing depth is selected to be 1.0 mm.

[0098] It should be noted that the additive manufacturing in this embodiment is completed under the joint action of ultrasonic-assisted high-efficiency arc-friction stir processing composite additive manufacturing.

[0099] (3) After the split-flow plasma high-efficiency arc welding gun 401 completes the arc additive manufacturing process of this layer, the control device 101 controls the welding power supply 103 to turn off. After the processing tool 202 completes the processing task of this layer, it is lifted up again according to the lifting procedure and step (2) is repeated. This cycle is repeated to complete the ultrasonic-assisted high-efficiency arc-friction stir processing composite additive manufacturing.

[0100] (4) After the additive manufacturing is completed, the high-efficiency arc device is turned off first, and then the stir friction processing device and the ultrasonic device are turned off to complete the additive manufacturing of the sample to be added.

[0101] The first comparison

[0102] This comparative example provides a high-efficiency arc-friction stir processing additive manufacturing system 100, which differs from the first embodiment only in that during the additive manufacturing process, the ultrasonic device 300 is turned off and no ultrasonic-assisted additive manufacturing is provided. Figure 5 ,from Figure 5 It can be seen that the pores on the surface of the additive are coarse and unevenly distributed.

[0103] In summary, the high-efficiency arc-friction stir processing additive manufacturing system 100 and method provided by the present invention have the following characteristics:

[0104] (1) The manufacturing method provided by the embodiment of the present invention includes high-efficiency arc additive manufacturing, ultrasonic pulse coordinated control and high-rigidity stir friction processing. The manufacturing method has a simple process and single-system control, which solves the problems of poor quality stability of arc additive manufacturing and low additive efficiency of large components, and realizes a high-quality and efficient additive manufacturing process for large components.

[0105] (2) The embodiment of the present invention adopts an ultrasonic-assisted method to stabilize the arc additive manufacturing process while improving the quality and efficiency of stir friction processing, making it more suitable for process production.

[0106] (3) The split-flow high-efficiency arc additive device used in the embodiment of the present invention can reduce the heat input of the parent material while increasing the additive efficiency. At the same time, it adopts a pulse coordinated control method, which has specific advantages for the additive manufacturing of light alloys.

[0107] (4) The pulse coordinated control proposed in the present invention can be used in conjunction with ultrasonic assisted control. Through the coordinated control of the two, the intermediate process control of additive manufacturing can be achieved.

[0108] (5) The present invention effectively solves the problem of many pores in ordinary arc additive manufacturing, and at the same time solves the problem of insufficient rigidity of robot stir friction processing. It combines the traditional gantry-type stir friction processing device 200 with the newly invented split-flow high-efficiency arc welding, gives full play to the advantages of each process, and completes the stable control of the additive manufacturing process;

[0109] (6) The manufacturing system 100 proposed in the present invention is low-cost and can realize an automated additive manufacturing process, meeting the needs of modern industrial production.

[0110] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A high-efficiency arc-friction stir processing additive manufacturing system, characterized in that: The manufacturing system includes a control device, a friction stir processing device, a high-efficiency arc device and an ultrasonic device; The control device controls the high-efficiency arc device to perform additive manufacturing; the control device controls the friction stir processing device to perform friction stir processing; The ultrasonic device is arranged between the friction stir processing device and the high-efficiency arc device and is close to the friction stir processing device; The ultrasonic device is movably connected to the friction stir processing device; the control device controls the ultrasonic device to assist in additive manufacturing; The relative distance between the high-efficiency arc device and the friction stir processing device is ≤200 mm.

2. The manufacturing system according to claim 1, characterized in that: The high-efficiency arc device is a shunt plasma high-efficiency arc device, which includes a main power supply, a secondary power supply, a shunt plasma high-efficiency arc welding gun, a pulse current control mechanism, an additive base plate and a current sensor; the shunt plasma high-efficiency arc welding gun includes a wire feeder, a water-cooled copper sleeve, an annular plasma electrode, and a shunt plasma additive manufacturing arc system; The positive electrode of the main power supply is connected to the wire feeder, and the negative electrode is connected to the sample to be added, and the main arc is formed through the shunt plasma additive manufacturing arc system; the positive electrode of the auxiliary power supply is connected to the wire feeder, and the negative electrode is connected to the water-cooled copper sleeve, and the bypass arc is formed after being connected through the annular plasma electrode and the bypass shunt arc; The bypass arc and the main arc are coupled together to form a composite arc; The pulse current control mechanism coordinates and controls the bypass current and the main current, and includes a pulse signal controller and a pulse signal processor; The pulse signal processor detects the main current pulse signal of the current sensor. When it is detected that the main current is at the pulse base value, the pulse signal controller is triggered to adjust the bypass current to the pulse base value to ensure the stability of the composite arc during welding; When it is detected that the main current pulse is at its peak value, the trigger pulse signal controller adjusts the bypass current pulse to its peak value, thereby ensuring low workpiece heat input during welding.

3. The manufacturing system according to claim 2, characterized in that: The split-flow plasma high-efficiency arc welding gun also includes an insulating porcelain sleeve, a conductive nozzle, a protective gas hood, a plasma restraining nozzle and a welding wire.

4. The manufacturing system according to claim 1, characterized in that: The control device includes a processing power supply and a welding power supply; wherein the processing power supply is connected to the friction stir processing device, and the welding power supply is connected to the high-efficiency arc device.

5. The manufacturing system according to claim 1, characterized in that: The friction stir processing device comprises a detachably connected processing spindle and a processing tool, wherein the processing spindle is connected to a processing power source, and the processing tool is in contact with the additive material during the friction stir processing; A fixing fixture is arranged on one side of the machining spindle close to the machining tool.

6. The manufacturing system according to claim 1, characterized in that: The ultrasonic device comprises an ultrasonic probe and a slide rail which are slidably connected, wherein the ultrasonic probe contacts the additive material during friction stir processing; The ultrasonic device is movably connected to a fixing fixture on the processing spindle.

7. A method for processing additive materials using the manufacturing system according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) Grind the surface of the base plate and the additive parts of the sample to be added, and perform tooling according to the requirements of additive manufacturing; (2) Starting the ultrasonic device and the high-efficiency arc device to realize the ultrasonic-assisted high-efficiency arc additive manufacturing process in the initial stage; After the processing tool of the friction stir processing device reaches the specified position, the processing power supply is started to simultaneously realize ultrasonic-assisted high-efficiency arc additive manufacturing and friction stir processing; (3) After completing one layer of additive manufacturing, the step (2) is repeated to continue the additive manufacturing; (4) After the additive manufacturing is completed, the high-efficiency arc device is turned off first, and then the stir friction processing device and the ultrasonic device are turned off to complete the additive manufacturing of the sample to be added.

8. The method according to claim 7, characterized in that During the additive manufacturing process, the wire elongation is 10mm-13mm, the wire feeding speed is 5m / min-10m / min, the additive speed is 0.3m / min-0.5m / min, the length of each stacking layer is 220mm-5000mm, and the height of the additive workpiece is 5mm-450mm when the stacking is completed.

9. The method according to claim 7, characterized in that: The rotation speed of the friction stir processing process is 800rpm-1500rpm, the travel speed is 0.1m / min-0.3m / min, and the pressing depth is 0.5mm-1.5mm; The diameter of the stirring head shoulder of the processing tool is 8mm-12mm, the length of the stirring needle is 1.3mm-2.7mm, and the diameter of the stirring needle is 1.5-2.5mm.

10. The method according to claim 7, characterized in that The additive method used in additive manufacturing is unidirectional additive; argon is used as the protective gas in the additive manufacturing process, and the flow rate of the protective gas is 8L / min-25L / min.

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