CN115091001B - Arc additive manufacturing method and system for free-support metal rod piece in any angle space - Google Patents

Arc additive manufacturing method and system for free-support metal rod piece in any angle space Download PDF

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CN115091001B
CN115091001B CN202210789371.7A CN202210789371A CN115091001B CN 115091001 B CN115091001 B CN 115091001B CN 202210789371 A CN202210789371 A CN 202210789371A CN 115091001 B CN115091001 B CN 115091001B
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wire
diameter
current
molten pool
metal rod
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CN115091001A (en
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刘长猛
敬晨晨
徐田秋
毛昊
李坤
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Beijing Institute of Technology BIT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/04—Welding for other purposes than joining, e.g. built-up welding
    • B23K9/044—Built-up welding on three-dimensional surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/095—Monitoring or automatic control of welding parameters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/12—Automatic feeding or moving of electrodes or work for spot or seam welding or cutting
    • B23K9/133—Means for feeding electrodes, e.g. drums, rolls, motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y50/00—Data acquisition or data processing for additive manufacturing
    • B33Y50/02—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

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  • Plasma & Fusion (AREA)
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  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Arc Welding In General (AREA)

Abstract

The invention relates to an electric arc additive manufacturing method and system for an unsupported metal rod piece in any angle space, in particular to the technical field of metal additive manufacturing. The method comprises the following steps: obtaining current calculation parameters, the diameter of the unsupported metal rod and the diameter of the wire, wherein the current calculation parameters comprise: the average current of the electric arc, the average voltage of the electric arc, the efficiency of a welding machine, the current of the wire, the resistance of the wire, the surface area of a molten pool, the specific heat capacity of the wire, the heat transfer coefficient of the surface of the molten pool and the heat transfer coefficient of a molten pool material; calculating the current value of the welding gun according to the current calculation parameter; calculating the wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire; and performing electric arc additive manufacturing on the unsupported metal rod piece according to the wire feeding speed and the current value of the welding gun. The invention can prepare the spatial unsupported rod piece with any angle, and provides possibility for manufacturing more complex cell configurations by additive manufacturing.

Description

Arc additive manufacturing method and system for free-support metal rod piece in any angle space
Technical Field
The invention relates to the technical field of metal additive manufacturing, in particular to an arc additive manufacturing method and system for an arbitrary angle space unsupported metal rod piece.
Background
The lattice structure has the advantages of light weight, high specific stiffness, high specific strength and the like, has the functions of shock absorption, energy absorption and the like, and is the best choice for lightening the weight, improving the strength and the rigidity of a plurality of structures. Due to the fact that the metal lattice space structure is complex, the traditional processing method is difficult to meet the preparation requirements in terms of process and cost, and the additive manufacturing technology greatly solves the preparation problem of the complex space lattice structure.
The additive manufacturing technology is a layer-by-layer stacking manufacturing technology from bottom to top, and theoretically can prepare various structures, but most of the existing additive manufacturing technologies cannot prepare cantilever structures without support. The space cantilever rod piece is a basic component of a lattice structure, and although the existing powder-laying type additive manufacturing has mature application in the aspect of preparing the lattice structure, the powder support and the rod piece are utilized to support the space rod piece prepared by the powder-laying type additive manufacturing such as a selective laser melting technology, and the method can only form the space rod unit with an included angle of more than 20 degrees with the horizontal direction and cannot form the space rod unit with a smaller angle or even a negative angle. The use of powder-laid additive manufacturing techniques to produce lattice structures is therefore greatly limited in the configuration of the cells.
At present, the preparation of lattice structures by electric arc additive manufacturing is still in the initial stage, and related researches are less. Low carbon steel, non-strut bars and BCC lattice structures with 90-30 ° tilt angles were prepared using GMAW technology by Takeyuki Abea et al, jade university, \22524. And LiYongjie et al, university of science and technology, in Huazhong, also used GMAW technology to prepare aluminum alloy non-support rods and lattice structures with inclination angles of 90-15 degrees. The GMAW technology utilizes the self-cooled rod piece as a support to provide a supporting force for a molten pool when an unsupported metal rod piece is prepared so as to resist the gravity borne by the molten pool and further avoid the collapse of the molten pool.
Xutian autumn et al (2021) of Beijing university of Richardson additive manufacturing task group prepares 90-0 degrees of titanium alloy support-free rods by using hot wire assisted GTAW additive manufacturing technology. In conclusion, due to the principle of additive manufacturing layer-by-layer accumulation, the existing additive manufacturing process can only manufacture the unsupported space rod units of 0 degree or more, and no good solution is provided for the negative angle rod units, so that the optimal design of the lattice structure is greatly limited.
Disclosure of Invention
The invention aims to provide an arc additive manufacturing method and system for an unsupported metal rod piece in any angle space, which can be used for preparing the space rod piece in any angle under the condition of no support.
In order to achieve the purpose, the invention provides the following scheme:
an arc additive manufacturing method of an arbitrary-angle spatial unsupported metal rod, comprising:
obtaining current calculation parameters, the diameter of the unsupported metal rod and the diameter of the wire, wherein the current calculation parameters comprise: the average current of the electric arc, the average voltage of the electric arc, the efficiency of a welding machine, the current of the wire, the resistance of the wire, the surface area of a molten pool, the specific heat capacity of the wire, the heat transfer coefficient of the surface of the molten pool and the heat transfer coefficient of a molten pool material;
calculating the wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire;
calculating the current value of the welding gun according to the current calculation parameter, the diameter of the wire and the wire feeding speed;
and performing electric arc additive manufacturing on the unsupported metal rod piece according to the wire feeding speed and the current value of the welding gun.
Optionally, when the current applied to the welding gun is a pulse current, the current value includes a peak current value, a base current value and a duty ratio.
An arc additive manufacturing system for an arbitrary angle spatial unsupported metal rod, comprising:
the welding device comprises a contact tube, a wire feeder, a numerical control system, a welding machine, a welding gun and a substrate; an unsupported metal bar is arranged on the substrate; the numerical control system is respectively connected with the welding gun, the welding machine and the wire feeder; the welding machine is connected with the welding gun; the wire feeder is connected with the contact nozzle; the numerical control system is used for calculating the wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire material and controlling the wire feeder according to the wire feeding speed, the numerical control system is used for controlling the moving speed of the welding gun, the numerical control system is used for calculating the current value of the welding gun according to the current calculation parameter, the diameter of the wire material and the wire feeding speed and controlling the welding machine to generate current according to the current value; the wire feeder is used for feeding the wire to an electric arc generated by the welding gun through the contact tube; the current calculation parameters include: average current of the arc, average voltage of the arc, efficiency of the welder, current of the wire, resistance of the wire, surface area of the molten pool, specific heat capacity of the wire, heat transfer coefficient of the surface of the molten pool, and heat transfer coefficient of the material of the molten pool.
Optionally, the arc additive manufacturing system of the unsupported metal rod in any angle in space further includes: and the hot wire machine is respectively connected with the numerical control system, the contact nozzle and the substrate.
Optionally, the negative electrode of the welding machine is connected to the welding gun, and the positive electrode of the welding machine is connected to the substrate.
Optionally, the negative electrode of the hot wire machine is connected with the contact nozzle, and the positive electrode of the hot wire machine is connected with the substrate.
Optionally, the substrate comprises: the base plate is arranged on the workbench.
Optionally, the arc additive manufacturing system of the unsupported metal rod at any angle in space further includes: and the shielding gas container is connected with the welding machine.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the method comprises the steps of obtaining current calculation parameters, the diameter of an unsupported metal rod piece and the diameter of a wire material, wherein the current calculation parameters comprise: the current of the wire, the resistance of the wire, the surface area of a molten pool, the specific heat capacity of the wire, the heat transfer coefficient of the surface of the molten pool and the heat transfer coefficient of the material of the molten pool; calculating the current value of the welding gun according to the current calculation parameter; calculating the wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire; and performing electric arc additive manufacturing on the unsupported metal rod piece according to the wire feeding speed and the current value of the welding gun, and preparing the space rod piece with any angle by controlling the current value of the welding gun.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a flowchart of an arc additive manufacturing method for a supportless metal rod according to an embodiment of the present invention;
FIG. 2 is a schematic view of an arc additive manufacturing system without a support metal rod;
FIG. 3 is a schematic diagram of a pulsed current;
FIG. 4 is a flow chart of the overall preparation of a non-support rod;
FIG. 5 is a flow chart of a manufacturing process of a positive angle strut-less bar;
FIG. 6 is a negative angle non-strut bar preparation flow chart;
FIG. 7 is a graph showing the results of a screw rod prepared by the method of the present invention;
FIG. 8 is a graph showing the results of making 316L stainless steel rod members having different diameters at an inclination angle of 45 degrees by the method of the present invention;
FIG. 9 is a graph showing the results of different angle rods made using the method provided by the embodiments of the present invention.
Description of the symbols:
1-a hot wire machine; 2-a contact tip; 3-a wire feeder; 4-a numerical control system; 5-welding machine; 6-a welding gun; 7-a shielding gas container; 8-unsupported metal rods; 9-a substrate; 10-a workbench.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, an embodiment of the present invention provides an arc additive manufacturing method for a supportless metal rod, including:
step 101: obtaining current calculation parameters, the diameter of the unsupported metal rod and the diameter of the wire, wherein the current calculation parameters comprise: arc mean current, arc mean voltage, welder efficiency, current of the wire, resistance of the wire, bath surface area, specific heat capacity of the wire, bath surface heat transfer coefficient, and heat transfer coefficient of the bath material.
Step 102: and calculating the wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire.
Step 103: and calculating the current value of the welding gun according to the current calculation parameter, the diameter of the wire and the wire feeding speed.
Step 104: and performing electric arc additive manufacturing on the unsupported metal rod piece according to the wire feeding speed and the current value of the welding gun.
In practical application, the wire feeding speed calculated according to the diameter of the unsupported metal rod and the diameter of the wire is specifically as follows:
depending on the diameter of the rod unit to be prepared, the required wire feed speed can be calculated according to the conservation of mass:
Figure BDA0003729613250000041
wherein v is Silk The wire feeding speed is set; d is the diameter of the rod unit to be prepared, namely the diameter of the unsupported metal rod piece; v is the moving speed of the machine tool; d is the wire diameter.
In practical applications, determination of heat input (power):
the heat input is the key for preparing the unsupported rod piece, the heat input is too large, the molten pool collapses to cause that the shape cannot be formed, the heat input is too small, the rod diameter can become small, the rod diameter is not matched with the wire feeding speed, and the arc length is reduced or even the arc length is contacted with a tungsten electrode. The heat input may be determined by the following equation:
to maintain the dynamic balance of the rod unit, the heat input of the bath is equal to the heat output, i.e.:
H i ＝Q
wherein H i For heat input per unit time of the bath, consisting essentially of two parts, i.e. heat input H provided by the arc a And heat input H provided by hot wire device w Namely:
H i ＝H a +H w
arc heat input per unit time: h a ＝I a ×V a X η, wherein I a Is the average current of the arc, V a The arc average voltage, related to arc length, can be read on the welder, and η is the welder efficiency.
If the current is a pulse current I a ＝I p ×λ+I b ×(1-λ)；
Wherein: i is p Is the peak current, I b Is the base current and λ is the duty cycle.
Hot wire heat input per unit time:
Figure BDA0003729613250000051
wherein I w Is the current of the wire, R w The resistance of the wire (the resistance of the wire from the contact nozzle to the molten pool), omega the hot wire electrifying rate and zeta the hot wire efficiency.
Q is heat quantity flowing out of the molten pool in unit time, and mainly comprises heat convection Q with the shielding gas To pair Heat conduction q of the rod Guide tube And the heat q required for melting the wire Fusion furnace The heat lost by the heat radiation is negligible. Namely: q = Q To pair +q Guide tube +q Fusion furnace 。
Convective heat transfer q To pair ＝AhΔt m Wherein A is the surface area of the molten pool, h is the heat transfer coefficient of the surface of the molten pool, and delta t m Is the average temperature difference between the surface of the molten pool and the fluid.
Heat transfer and conduction heat q Guide tube And (4) S multiplied by G multiplied by K, wherein S is the area of a solid-liquid interface of a molten pool, G is the temperature gradient of the solid-liquid interface, and K is the heat conduction coefficient of a molten pool material.
Figure BDA0003729613250000052
Wherein R is the solidification speed which is equal to the moving speed of the molten pool when the molten pool maintains dynamic balance, namely equal to the moving speed of a machine tool,
Figure BDA0003729613250000061
where T is temperature, T is time, T L Is the material liquid quadrant temperature, T S At the solidus temperature of the material, Δ t is the time for the material to reach the solidus temperature from the liquidus.
Figure BDA0003729613250000062
Wherein: ρ: the density of the material; d, the diameter of the wire; v: a wire feed speed; t is 0 : initial temperature of wire; t is a unit of m : melting point of the wire; c, specific heat capacity; h Diving Latent heat of fusion of the material;
in summary, calculating the current value of the welding gun according to the current calculation parameter specifically includes:
Figure BDA0003729613250000063
thus: can be regulated by regulating I p ，λ，I b The heat input is controlled to complete the preparation of the rod unit, specifically, the heat input is finally influenced by the duty ratio, the peak current and the base current, the heat input can be prepared as long as the actual heat input is the same, the two variables can be generally controlled to adjust the other variable, such as the base current and the peak current, the duty ratio is obtained through calculation to ensure the heat input, or the base current and the duty ratio are maintained to ensure the heat input through calculation of the peak current.
In practical application, when the current applied to the welding gun is a pulse current, the current value includes a peak current value, a base current value and a duty ratio, as shown in fig. 4, the overall concept is as follows: the electric arc melts the wire material and the rod piece during the peak current period to form a molten pool, the molten pool is cooled during the base current period to prevent the molten pool from collapsing or dropping due to overlarge volume caused by overlarge heat input, and the preparation without the support rod is finally completed through the continuous repeated heating melting and cooling solidification of the molten pool.
In practical application, the preparation of the unsupported space rod piece can be completed by reasonably controlling heat input (current value of a welding gun) whether direct current constant current or alternating current can maintain the stability of a molten pool.
As shown in fig. 2, an embodiment of the present invention further provides an arc additive manufacturing system, also referred to as hot-wire inert gas shielded welding apparatus, for unsupported metal rods, including:
the welding device comprises a contact tube 2, a wire feeder 3, a numerical control system 4, a welding machine 5, a welding gun 6 and a substrate; an unsupported metal bar 8 is disposed on the base; the numerical control system 4 is respectively connected with the welding gun 6, the welding machine 5 and the wire feeder 3; the welding machine 5 is connected with the welding gun 6; the wire feeder 3 is connected with the contact tube 2; the numerical control system 4 is used for calculating a wire feeding speed according to the diameter of the unsupported metal rod 8 and the diameter of a wire and controlling the wire feeder 3 according to the wire feeding speed, the numerical control system 4 is used for controlling the moving speed of the welding gun 6, the numerical control system 4 is used for calculating the current value of the welding gun 6 according to a current calculation parameter, the diameter of the wire and the wire feeding speed and controlling the welding machine 5 to generate current according to the current value; the wire feeder 3 is used for feeding the wire to an electric arc generated by the welding gun 6 through the contact tip 2; the current calculation parameters include: arc mean current, arc mean voltage, welder efficiency, current of the wire, resistance of the wire, bath surface area, specific heat capacity of the wire, bath surface heat transfer coefficient, and heat transfer coefficient of the bath material.
In practical applications, the arc additive manufacturing system of the unsupported metal rod 8 further includes: and the hot wire machine 1 is respectively connected with the numerical control system 4, the contact tip 2 and the substrate.
In practical applications, the negative electrode of the welding machine 5 is connected to the welding gun 6, and the positive electrode of the welding machine 5 is connected to the substrate.
In practical application, the negative electrode of the hot wire machine 1 is connected with the contact tip 2, and the positive electrode of the hot wire machine 1 is connected with the substrate.
In practical applications, the substrate comprises: the welding machine comprises a base plate 9 and a workbench 10, wherein the base plate 9 is arranged on the workbench 10, and the anode of the welding machine 5 and the anode of the hot wire machine 1 are connected with the workbench 10.
In practical applications, the arc additive manufacturing system of the unsupported metal rod 8 further includes: and a shielding gas container 7 connected with the welding machine 5.
The working process of the hot wire inert gas shielded welding equipment comprises the following steps: the current generated by the hot wire machine 1 forms a loop through the contact tip 2 → the wire → the unsupported metal rod 8 → the substrate 9 → the workbench 10, and because the diameter of the wire is small (0.8 mm-3.2 mm), huge resistance exists between the contact tip 2 and the molten pool, and when the current passes through, a large amount of resistance heat can be generated, so that the wire is heated. The wire feeder 3 is controlled by a numerical control system 4 to feed the wire to the arc. The numerical control system 4 is capable of controlling the hot wire machine 1, the wire feeder 3, the welder 5 and the welding gun 6. A welder 5 generates an electric current through a welding torch 6 to create an arc between the tungsten electrode and the shaped rod to melt the wire to the rod. The welding gun 6 can be connected with a multi-axis mechanical arm or a machine tool and is controlled by the numerical control system 4 to move. A shielding gas vessel 7 holds a shielding gas, typically argon, which is delivered to a welding torch 6 through a welder 5 to shield the molten metal from the atmosphere. The base plate 9 can also be a part for manufacturing the unsupported metal rod 8, and the worktable 10 is used for fixing a workpiece and grounding, so that the welding machine 5 and the hot wire machine 1 form a circuit by current.
The invention also provides an embodiment of using low-frequency (0.5 Hz-2 Hz) pulse current to perform additive manufacturing by using the arc additive manufacturing method of the unsupported metal rod, as shown in FIG. 3, the peak current is 30A-200A, the peak current is adjusted according to the diameter of the rod, the base current is 5A-30A, and the duty ratio is 3% -100%. Wherein the wire and the parent metal (rod) are fused at the time of peak current to form a molten pool, and the molten pool is cooled and solidified at the time of base value. The preparation between the space rods can be finished by adjusting pulse current parameters (the peak current, the base current and the duty ratio are specifically shown in tables 1 and 2). The specific preparation process is as follows according to the angle of the rod unit: the positive angle and the negative angle (the angle between the forming direction of the rod unit and the horizontal direction) are divided into two processes, and the results are shown in fig. 7, fig. 8 and fig. 9, in which fig. 7 is a screw rod, fig. 8 is a 316L steel rod piece with different diameters and an inclination angle of 45 °, and fig. 9 is a rod with different angles, which are-30 °, 90 °, 60 °, 30 ° and 0 ° from left to right, respectively.
The preparation process of the positive-angle support-rod-free unit comprises the following steps:
fig. 5 is a flow chart of the manufacturing process of the positive angle knighthead-free unit in one pulse current cycle. Under the peak current, a large molten pool is formed, and the molten pool is kept stable by the self supporting force between the rods and the surface tension and self gravity of liquid metal of the molten pool. At the moment, the size of a molten pool is controlled by adjusting rod diameter parameters according to the rod diameter forming diameter, so that flowing and collapse caused by overlarge molten pool are prevented; after the peak current is over, the base current is reached, during which the bath is gradually cooled and solidified. At the moment, wire feeding is still continued, because the heat input is small during the base value period, the wire can be melted and accumulated above the solidification molten pool to form a small packet, after the peak current arrives again, the small packet can be melted to form the molten pool, the positive-angle support-free rod can be manufactured repeatedly, the interference between the rod piece and the welding gun 6 needs to be avoided in the forming process, and the rod unit with any angle can be manufactured by adjusting the inclination angle of the welding gun 6.
The preparation process of the negative-angle support-rod-free unit comprises the following steps:
fig. 6 is a flow chart of the manufacturing process of the positive angle knighthead-free unit in one pulse current cycle. At peak current, a large molten pool is formed, which is stabilized by its own adhesion between the rods, and by the surface tension of the molten pool liquid metal and its own gravity. At the moment, the size of a molten pool is controlled according to the forming diameter of the rod diameter, the phenomenon that the molten pool is too large to cause dripping is prevented, and the phenomenon that the molten pool is too small to flow downwards is prevented; after the peak current is over, the base current is reached, during which the bath is gradually cooled and solidified. At the moment, wire feeding is still continued, because the heat input is small during the base value period, the wire can be melted and accumulated above the solidification molten pool to form a small packet, after the peak current comes again, the small packet can be melted to form the molten pool, the molten pool flows downwards, the negative-angle support-free rod can be manufactured repeatedly, the interference between the rod piece and the welding gun 6 needs to be avoided in the forming process, and the rod unit with any angle can be manufactured by adjusting the inclination angle of the welding gun 6.
TABLE 1 different diameters 316L stainless steel rod unit 45 degree dip angle preparation parameter table
Figure BDA0003729613250000091
TABLE 2 parameter table for 316LSS stainless steel preparation with different dip angles
Figure BDA0003729613250000092
The invention has the following technical effects:
1. the method has high forming efficiency, the method does not need to wait for arc quenching in the forming process, the cooling of a molten pool is completed in the period of pulse current basic value, and the forming efficiency is 10 times higher than that of the GWAW technology.
2. According to the invention, the rod unit with any angle can be formed by controlling the current value and further controlling the flow solidification of the molten pool, the preparation of the negative-angle rod piece can be realized under the condition of no support requirement by the technology, and a solution is provided for the manufacture of a complex space lattice structure.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.

Claims (7)

1. An electric arc additive manufacturing method of an arbitrary angle space unsupported metal rod piece is characterized by comprising the following steps:
obtaining current calculation parameters, the diameter of the unsupported metal rod and the diameter of the wire, wherein the current calculation parameters comprise: the average current of the electric arc, the average voltage of the electric arc, the efficiency of a welding machine, the current of a wire, the resistance of the wire, the surface area of a molten pool, the specific heat capacity of the wire, the heat transfer coefficient of the surface of the molten pool and the heat transfer coefficient of a molten pool material;
calculating the wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire;
calculating the current value of the welding gun according to the current calculation parameter, the diameter of the wire and the wire feeding speed;
performing electric arc additive manufacturing on the unsupported metal rod piece according to the wire feeding speed and the current value of the welding gun;
the wire feeding speed calculated according to the diameter of the unsupported metal rod piece and the diameter of the wire material is specifically as follows:
depending on the diameter of the rod unit to be prepared, the required wire feed speed can be calculated according to the conservation of mass:
Figure QLYQS_1
wherein
Figure QLYQS_2
The wire feeding speed is set; d is the diameter of the rod unit to be prepared, namely the diameter of the unsupported metal rod piece; />
Figure QLYQS_3
The moving speed of the machine tool; d is the diameter of the wire;
the calculating the current value of the welding gun according to the current calculation parameter, the diameter of the wire and the wire feeding speed specifically comprises:
according to
Figure QLYQS_13
Regulating and controlling>
Figure QLYQS_6
，/>
Figure QLYQS_10
，/>
Figure QLYQS_7
To control the current value of the welding gun, wherein>
Figure QLYQS_9
Is the peak current->
Figure QLYQS_12
Is duty ratio->
Figure QLYQS_17
Is a base value current, is greater than or equal to>
Figure QLYQS_18
Is the average voltage of the arc->
Figure QLYQS_21
For the efficiency of the welding machine>
Figure QLYQS_5
For the current of a filament>
Figure QLYQS_14
Is the resistance of the wire between the contact nozzle and the molten pool>
Figure QLYQS_15
Is the hot wire power-on rate>
Figure QLYQS_19
For hot wire efficiency, A is the bath surface area, h is the heat transfer coefficient of the bath surface, and->
Figure QLYQS_16
Is the average temperature difference between the surface of the molten pool and the fluid, and S is the solid-liquid boundary of the molten poolThe area of the surface, G is the temperature gradient of the solid-liquid interface, K is the heat conduction coefficient of the molten pool material, and K is the heat conduction coefficient of the molten pool material>
Figure QLYQS_20
Is the material density; />
Figure QLYQS_4
The initial temperature of the wire material; />
Figure QLYQS_8
Is the melting point of the wire; c is specific heat capacity; />
Figure QLYQS_11
Is the latent heat of fusion of the material, and T is the temperature of the wire.
2. An arc additive manufacturing system for an arbitrary angle spatial unsupported metal rod, comprising:
the welding device comprises a contact nozzle, a wire feeder, a numerical control system, a welding machine, a welding gun and a substrate; an unsupported metal bar is disposed on the substrate; the numerical control system is respectively connected with the welding gun, the welding machine and the wire feeder; the welding machine is connected with the welding gun; the wire feeder is connected with the contact nozzle; the numerical control system is used for calculating wire feeding speed according to the diameter of the unsupported metal rod piece and the diameter of the wire material and controlling the wire feeder according to the wire feeding speed, the numerical control system is used for controlling the moving speed of the welding gun, the numerical control system is used for calculating the current value of the welding gun according to current calculation parameters, the diameter of the wire material and the wire feeding speed and controlling the welding machine to generate current according to the current value; the wire feeder is used for feeding the wire to an electric arc generated by the welding gun through the contact tube; the current calculation parameters include: the average current of the electric arc, the average voltage of the electric arc, the efficiency of a welding machine, the current of the wire, the resistance of the wire, the surface area of a molten pool, the specific heat capacity of the wire, the heat transfer coefficient of the surface of the molten pool and the heat transfer coefficient of a molten pool material;
the wire feeding speed calculated according to the diameter of the unsupported metal rod piece and the diameter of the wire material is specifically as follows:
depending on the diameter of the rod unit to be prepared, the required wire feed speed can be calculated according to the conservation of mass:
Figure QLYQS_22
wherein
Figure QLYQS_23
The wire feeding speed is set; d is the diameter of the rod unit to be prepared, namely the diameter of the unsupported metal rod piece; />
Figure QLYQS_24
The moving speed of the machine tool; d is the diameter of the wire;
according to
Figure QLYQS_32
Regulating and controlling>
Figure QLYQS_26
，/>
Figure QLYQS_29
，/>
Figure QLYQS_28
To control the current value of the welding gun, wherein>
Figure QLYQS_31
Is the peak current->
Figure QLYQS_35
Is duty ratio->
Figure QLYQS_38
Is a base value current, is greater than or equal to>
Figure QLYQS_34
Is the average voltage of the arc->
Figure QLYQS_39
For the efficiency of the welding machine>
Figure QLYQS_27
For the current of the silk material>
Figure QLYQS_30
For the resistance of the wire between the contact nozzle and the molten bath>
Figure QLYQS_37
Is the hot wire power-on rate>
Figure QLYQS_40
For hot wire efficiency, A is the bath surface area, h is the heat transfer coefficient of the bath surface, and->
Figure QLYQS_41
Is the average temperature difference between the surface of the molten pool and the fluid, S is the area of the solid-liquid interface of the molten pool, G is the temperature gradient of the solid-liquid interface, K is the heat conduction coefficient of the molten pool material, and K is the temperature gradient of the molten pool material>
Figure QLYQS_42
Is the material density; />
Figure QLYQS_25
The initial temperature of the wire material; />
Figure QLYQS_33
Is the melting point of the wire; c is the specific heat capacity; />
Figure QLYQS_36
Is the latent heat of fusion of the material, and T is the temperature of the wire.
3. The arc additive manufacturing system of any angle spatial unsupported metal rods of claim 2, further comprising: and the hot wire machine is respectively connected with the numerical control system, the contact nozzle and the substrate.
4. The system of claim 2, wherein the negative pole of the welder is connected to the welding gun, and the positive pole of the welder is connected to the substrate.
5. The system according to claim 3, wherein a negative electrode of the hot-wire machine is connected to the contact tip, and a positive electrode of the hot-wire machine is connected to the substrate.
6. The arc additive manufacturing system according to claim 2, wherein said base comprises: the base plate is arranged on the workbench.
7. The arc additive manufacturing system of any angle spatial unsupported metal rods of claim 2, further comprising: and the shielding gas container is connected with the welding machine.
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