Efficient MIG arc additive method and device without a common bath

Abstract

The application belongs to the field of electric arc additive technology, and particularly relates to a high-efficiency MIG electric arc additive method and device without a common molten pool. A linearly arranged additive three-wire welding gun is adopted, three electric arcs are ignited through coordinated control of a power supply, and small-current sequential lap joint or large-current gap lap joint additive of the three-wire deposited metal is realized through welding gun pose adjustment. The three wires can be of the same or different wire materials, and the interlaced additive of the same or different metals can be realized, and the efficiency can be three times that of ordinary single-wire electric arc additive. The device is simple to operate, the three-wire additive process is stable, excellent additive forming quality can be obtained, the electric arc additive efficiency can be greatly improved, and the interlaced additive of different metals can be realized.

Description

[0001] The application is a divisional application, whose parent application is an application with the application date of December 29, 2021, the application number of 202111634530.8, and the invention name of 'A high-efficiency MIG electric arc additive method and device without a common molten pool'. TECHNICAL FIELD

[0002] The application belongs to the technical field of electric arc additive manufacturing, and particularly relates to a high-efficiency MIG electric arc additive method and device without a common molten pool. BACKGROUND

[0003] Electric arc additive manufacturing is attracting more and more attention due to its low manufacturing cost and high material utilization rate, and is particularly suitable for efficient and rapid forming of large and complex structural parts, and has a broad application prospect in the fields of national defense, aerospace, energy and power. However, the current MIG electric arc additive manufacturing process mostly uses single-wire electric arc additive manufacturing, and for thick-walled structural parts, the additive manufacturing efficiency needs to be improved compared with traditional casting, forging and machining.

[0004] For single-wire MIG electric arc additive manufacturing, the deposition efficiency can only be improved by increasing the wire diameter and adjusting the welding process parameters. When the wire diameter is constant, the maximum allowable current is limited, and when the maximum allowable current is exceeded, the arc shape and droplet transfer are unstable, causing serious spatter, and even burning out the welding torch. If the wire diameter is increased, the additive current needs to be increased, but at the same time, the heat input to the substrate or the previous additive metal is also increased, which can cause excessive melting of the substrate or the previous additive metal, resulting in unstable additive molten pool and decreased forming quality.

[0005] Meanwhile, researchers have improved the additive efficiency by using double-wire MIG electric arc additive manufacturing, but the distance between the two wires cannot be adjusted, and the arcs generated by the two wires are combined into one. This scheme can improve the additive efficiency to a certain extent, but it cannot adjust the distance between the wires, and the process parameters are not flexible. When using dissimilar wires, the two types of wires are fully mixed under the action of arc pressure and other forces, and it is difficult to form a gradient material feature between the dissimilar wires, which can also cause defects in the microstructure of the additive sample and is difficult to control. SUMMARY

[0006] The purpose of the present application is to provide a high-efficiency MIG electric arc additive method and device without a common molten pool.

[0007] The technical solution for achieving the purpose of the present application is a high-efficiency MIG electric arc additive method without a common molten pool, which is suitable for 200-350A high-current additive manufacturing, and includes the following steps:

[0008] Step (1): three welding torches are arranged in a straight line on the mounting plate, the distance D between adjacent welding torches is adjustable, and the angle between the center line of the three welding torches and the additive weld is α;

[0009] Step (2): adjust D and α to make 4L / 3≤D·sinα≤3L / 2, and α is 90°, wherein L is the deposition width of each welding wire during deposition, and there is a gap between the three deposited metals formed by the previous movement, and the power supply of the three welding wires alternately outputs the current peak value;

[0010] Step (3): the deposited metal formed by the second movement of the welding torch fills the gap formed by the first movement;

[0011] Step (4): repeat steps (2) and (3) to complete the arc additive manufacturing.

[0012] Further, the material of the welding wire used in the second movement of the welding torch in step (3) is different from the material of the welding wire used in the first movement of the welding torch, and the material of the welding wire used in each movement of the welding torch is the same.

[0013] A composite material prepared by the above method.

[0014] A high-efficiency MIG arc additive manufacturing method without sharing the pool, suitable for small current additive manufacturing of 60-200A, comprising the following steps:

[0015] Step (1): three welding torches are arranged in a straight line on the mounting plate, the distance D between adjacent welding torches is adjustable, and the angle between the center line of the three welding torches and the additive weld is α;

[0016] Step (2): adjust D and α to make L / 2≤D·sinα≤3L / 4, and 10°<α<80°, so that the three deposited metals formed by the first movement of the three-wire welding torch do not share the pool, and the three deposited metals realize sequential lapping, wherein the power supply of the three welding wires alternately outputs the current peak value;

[0017] Step (3): the three deposited metals formed by the second movement of the welding torch continue to sequentially lap the three deposited metals formed by the first movement;

[0018] Step (4): repeat steps (2) and (3) to complete the arc additive manufacturing.

[0019] Further, the material of the three welding wires of each pass, and the material of the welding wire of adjacent passes are determined as needed.

[0020] Further, the material of the middle welding wire of the three welding wires of each pass is austenitic stainless steel, and the two side welding wires are martensitic high-strength steel, and the materials of the welding wires of adjacent passes are the same.

[0021] A composite material prepared by the above method.

[0022] A device used by the above method, comprising a synergistic additive power supply, a three-wire wire feeding system, a linear three-wire additive gun, a mechanical motion system, a gas delivery system and a control system;

[0023] The synergistic additive power supply comprises three MIG power supplies that can communicate with each other, and the pulse phase control of the power supply output current is realized through the control system, the three power supplies output current peaks alternately, and the phase angles of the output current peaks are 120° apart;

[0024] The three-wire wire feeding system comprises three sets of wire feeding wheels, three sets of wire feeding motors, three sets of wire feeding interfaces and a set of housings, and simultaneously realizes the feeding of three welding wires;

[0025] The mechanical motion system is connected with the fixed mounting plate of the additive gun, drives the additive gun to move in space, and realizes the adjustment of the arc additive path and posture;

[0026] The gas delivery system is used to provide protective gas for the linear three-wire additive gun.

[0027] Further, the linear three-wire additive gun comprises a linear guide rail slider mechanism, a fixed mounting plate and three welding guns.

[0028] The three welding guns are mounted on the fixed mounting plate through the linear guide rail slider mechanism, and the distance between the adjacent welding guns of the three welding guns can be adjusted within the range of 10-25mm through the adjustment of the linear guide rail slider mechanism.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] (1) The welding gun of the present application comprises three welding guns controlled by three independent power supplies, and the distance between the three welding guns is controlled to prevent the three welding wires from sharing a molten pool, avoid the mutual interference between the arcs, and make the additive molten pool stable and the forming quality good; different types of wires can be used to improve the arc additive efficiency and realize the interlaced additive of dissimilar metals to form a gradient composite material and enhance the mechanical properties of the additive sample; when a large-current arc additive process is used, the three welding wires do not share a molten pool and have a gap between them, and the molten metal formed by the second movement fills the gap formed by the first movement, which can avoid excessive local heat accumulation, improve the heat dissipation conditions of the arc additive, reduce the overall temperature gradient of the component, and be beneficial to reducing the deformation and residual stress of the component.

[0031] (2) The three-wire welding gun is mounted on a set of mechanical system through a mounting plate, the system is simple and easy to operate, and overcomes the defects of the conventional multi-wire additive system, such as complex structure and difficult operation.

[0032] (3) Through the signal coordination device, the phase control of the output pulse current of the three MIG power sources is realized, the mutual interference between the three arcs is avoided, the droplet transfer is stable, and the additive spatter is reduced;

[0033] (4) The arc additive efficiency is high, and can be three times that of ordinary single-wire MIG arc additive. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a schematic diagram of linear three-wire high-efficiency arc additive.

[0035] Figure 2 It is a schematic diagram of gap lap arc additive process.

[0036] Figure 3 It is a schematic diagram of sequential lap arc additive process.

[0037] Figure 4 It is a schematic diagram of linear three-wire cooperative high-efficiency arc additive device structure.

[0038] Figure 5 It is a cooperative additive power current output waveform diagram.

[0039] Figure 6 It is a schematic diagram of linear three-wire welding gun structure.

[0040] BRIEF DESCRIPTION OF DRAWINGS

[0041] 1-linear three-wire additive gun, 2-gas delivery system, 3-three-wire wire feeding system, 4-mechanical movement system, 5-cooperative additive power source, 6-control system, 7-welding gun, 8-mounting plate, 9-sliding block, 10-guide rail. DETAILED DESCRIPTION

[0042] The application will be described in further detail below with reference to the drawings.

[0043] A linear three-wire cooperative high-efficiency MIG arc additive process method adopts a linearly arranged three-wire welding gun special for additive to carry out additive, three welding wires are arranged in a linear equal interval, the interval is adjustable, and three welding wires can melt three metal layers every time of movement, so that high-efficiency MIG arc additive is realized, and the efficiency can be three times that of ordinary single-wire MIG arc additive.

[0044] As shown in Figure 1 During the additive process, the wire axis is perpendicular to the additive surface, it is assumed that adjusting the additive process parameters makes the deposition width of each welding wire be L during additive, and different forms of high-efficiency additive process can be realized by adjusting the mutual interval D between the three wires and the included angle a between the connecting line of the three wires and the additive weld.

[0045] As shown in Figure 2As shown, if D and α are adjusted so that 4L / 3 ≤ D·sinα ≤ 3L / 2, the three weld pools formed by the first movement of the three-wire welding torch are not eutectic and have gaps between them, failing to overlap. The weld metal formed by the second movement needs to fill the gaps created by the first movement to achieve weld metal overlap. This additive manufacturing process is called high-current gap overlap additive manufacturing. Using this process in arc additive manufacturing can reduce excessive heat accumulation in localized areas and improve the heat dissipation conditions of the additive component, facilitating heat dissipation after additive manufacturing and reducing the overall temperature gradient of the additive component, thus reducing component deformation and residual stress. This process is suitable for wires with low thermal conductivity and good weld pool fluidity, but it is not suitable for wires with high thermal conductivity and poor fluidity, such as aluminum alloys. For example, by adjusting the additive manufacturing process parameters to make the single-pass weld width L 8mm, and then adjusting the distance D between the three wires to 11mm and the included angle α to 90°, the condition 4L / 3≤D·sinα≤3L / 2 is satisfied. At this time, arc additive manufacturing can be achieved through the non-eutectic pool additive manufacturing process.

[0046] like Figure 3 As shown, if D and α are adjusted so that L / 2 ≤ D·sinα ≤ 3L / 4, the three weld metals formed by the three-wire welding torch in one motion, although not forming a eutectic pool, overlap sequentially due to spatial relationships. The three weld metals formed in the second motion continue to overlap sequentially with those formed in the first motion. This additive manufacturing process is called low-current sequential overlap additive manufacturing. This process is suitable for wires with high thermal conductivity and poor weld pool fluidity. For example, if the additive manufacturing process parameters are adjusted so that the single-pass weld width L is 10mm, and the spacing D between the three wires is adjusted to 12mm and the included angle α to 45°, then the condition L / 2 ≤ D·sinα ≤ 3L / 4 is satisfied. In this case, arc additive manufacturing can be achieved through a eutectic pool additive manufacturing process.

[0047] In three-wire MIG arc additive manufacturing, the three wires can be of the same or different types, achieving interwoven additive manufacturing of the same or different metals. For example, when the middle wire is made of austenitic stainless steel and the two side wires are made of martensitic high-strength steel for eutectic pool additive manufacturing, the addition of austenitic stainless steel can effectively prevent additive cracking of the high-strength steel and increase the toughness of the additive structure. In contrast, when using ordinary single-wire MIG arc additive manufacturing, it is necessary to frequently change the welding wire to achieve interwoven additive manufacturing of dissimilar metals, which is time-consuming and labor-intensive. Alternatively, two independent single-wire MIG arc additive manufacturing machines can be used in conjunction to perform additive manufacturing, which is more complex.

[0048] To achieve the aforementioned linear three-wire synergistic high-efficiency MIG arc additive manufacturing process, this invention proposes a linear three-wire synergistic high-efficiency MIG arc additive manufacturing device, such as... Figure 4As shown, the device mainly consists of a synergistic additive power supply, a three-wire wire feeding system, a linear three-wire additive special gun, a mechanical motion system, a gas delivery system, a control system, etc.

[0049] The synergistic additive power supply consists of three MIG power supplies that can communicate with each other, and the pulse phase control of the power supply output current is realized through the control system. The three power supplies output pulse currents, and the pulse current peak duty ratio is ≤1 / 3. In order to avoid mutual interference between the three arcs, the three power supplies output current peaks alternately, and the phase angles of the output peak currents differ by 120°. As shown, Figure 5 When the pulse current peak duty ratio is θ / 360° (θ≤120°), if the power supply 1 current peak output phase interval is 0°-θ, then the power supply 2 current peak output phase interval is 120°-θ+120°, and the current 3 current peak output phase interval is 240°-θ+240°.

[0050] The three-wire wire feeding system is assembled by three sets of wire feeding wheels, wire feeding motors, wire feeding interfaces, and a set of housings, and can simultaneously realize the feeding of three welding wires.

[0051] As shown, Figure 6 The linear three-wire additive special gun installs three welding guns on the fixed mounting plate through the linear guide rail slider system, and the spacing between the three welding guns can be adjusted to 10-25 mm by adjusting the linear guide rail slider.

[0052] The mechanical motion system can be an industrial robot or a special mechanical structure, and the end is connected with the additive special gun mounting plate to drive the additive special gun to move in space and realize the adjustment of the arc additive path and posture.

[0053] The gas delivery system is used to provide shielding gas for the linear three-wire additive special gun, which can prevent the additive sample from being oxidized during additive;

[0054] The control system is used to control the working process of the whole device, and in addition, the control system includes a signal coordination device connected with the three MIG power supplies through communication interfaces, which can realize the phase control of the output currents of the three MIG power supplies.

[0055] Example 1

[0056] High-current and high-efficiency additive of 316L stainless steel samples.

[0057] Step (1): The 316L stainless steel sample model to be added is sliced using a slicing software, and the motion trajectory of each layer of the welding gun is planned. Each layer of path is classified into odd and even paths.

[0058] Step (2): three wires are made of 316L stainless steel, adjust the 316L stainless steel additive process parameters and the working posture of the welding gun and the distance between the welding guns, make them work in the large current additive process mode, and first complete the arc additive of the odd path, and then complete the arc additive of the even path;

[0059] Step (3): start the additive manufacturing equipment, pass the protective gas, set the three-wire coordinated power supply to realize the three-wire alternating arc striking according to the wire feeding speed, and feed the wire to carry out the N layer (initial N = 1) data additive;

[0060] Step (4): make N = N + 1, repeat step (3) until the whole sample is added.

[0061] Example 2

[0062] High-efficiency additive of high-strength steel / stainless steel gradient composite material.

[0063] Step (1): use the material slicing software to slice the high-strength steel / stainless steel gradient composite material model to be added, and plan the movement trajectory of each layer of welding gun;

[0064] Step (2): the middle wire is made of soft 316L austenitic stainless steel wire, and the two side wires are made of 18Ni(350) martensitic stainless steel wire, and the 316L and 18Ni(350) additive process parameters and the working posture of the welding gun are adjusted respectively, so that they work in the small current additive process mode;

[0065] Step (3): start the additive manufacturing equipment, pass the protective gas, set the three-wire coordinated power supply to realize the three-wire alternating arc striking according to the wire feeding speed, and feed the wire to carry out the N layer (initial N = 1) data additive;

[0066] Step (4): make N = N + 1, repeat step (3) until the whole sample is added.

Claims

1. A highly efficient MIG arc additive manufacturing method for non-eutectic pools, characterized in that, Suitable for low-current additive manufacturing (60-200A), including the following steps: Step (1): Arrange the three welding torches in a straight line on the mounting plate. The distance D between adjacent welding torches is adjustable. The angle between the line connecting the centers of the three welding torches and the additive weld bead is α. Step (2): Adjust D and α so that L / 2≤D·sinα≤3L / 4 and 10°<α<80°, so that the three welded metals formed by the three-wire welding gun in one movement are non-eutectic pools and the three welded metals are sequentially overlapped, wherein the power supply of the three welding wires alternately outputs the peak current. Step (3): The three weld metals formed by the second movement of the welding torch continue to overlap sequentially with the three weld metals formed by the first movement; Step (4): Repeat steps (2) and (3) to complete the arc additive manufacturing.

2. The method according to claim 1, characterized in that, In each pass, the middle welding wire is made of austenitic stainless steel, while the two side welding wires are made of martensitic high-strength steel. The welding wires in adjacent passes are made of the same material.

3. A composite material, characterized in that, Prepared using the method described in any one of claims 1-2.

4. An apparatus for using the method as described in any one of claims 1-2, characterized in that, It includes a collaborative additive power supply, a three-wire feeding system, a linear three-wire additive gun, a mechanical motion system, a gas delivery system, and a control system; The collaborative additive power supply includes three MIG power supplies that can communicate with each other. The control system realizes the pulse phase control of the power supply output current. The three power supplies alternately output the peak current, and the phase angle of the output peak current differs by 120°. The three-wire feeding system includes three sets of wire feeding wheels, three sets of wire feeding motors, three sets of wire feeding interfaces, and a housing, which can simultaneously feed three welding wires. The end of the mechanical motion system is connected to the fixed mounting plate of the additive gun, which drives the additive gun to move in space, thereby adjusting the path and attitude of the electric arc additive manufacturing. The gas delivery system is used to provide protective gas to the linear three-wire additive manufacturing gun.

5. The apparatus according to claim 4, characterized in that, The linear three-wire additive manufacturing gun includes a linear guide slider mechanism, a fixed mounting plate, and three welding guns. Three welding torches are mounted on a fixed mounting plate using a linear guide slider mechanism. The spacing between adjacent welding torches can be adjusted within the range of 10 to 25 mm by adjusting the linear guide slider mechanism.

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