Additive manufacturing device and manufacturing method based on hot wire friction micro-forging
Technical Field
The invention belongs to the technical field of solid-phase additive manufacturing, and particularly relates to an additive manufacturing device and method based on hot wire friction micro-forging.
Background
The additive manufacturing technology is applied to the forming of parts with complex structures, can greatly reduce the processing procedures and shorten the processing period, plays an important role in the fields of aerospace, war industry, ocean engineering equipment, medical appliances and the like, and shows unique advantages. At present, the main metal additive manufacturing technologies can be divided into two major categories, one is an additive manufacturing technology based on melting-solidification, such as laser/electron beam additive, electric arc additive and the like; the other is additive manufacturing technology based on solid phase connection theory, such as diffusion additive, friction additive, ultrasonic additive, cold spray additive and the like. Additive manufacturing techniques based on melting-solidification generally face problems of porosity, cracks, coarse structures, etc., and the properties of the manufactured parts still need to be further improved.
And the additive manufacturing technology based on solid phase connection can generally obtain compact additive manufacturing organization, and the comprehensive performance of parts is better. However, the existing solid-phase additive technology is generally low in additive efficiency. Taking diffusion material increase as an example, before material increase, slices are required to be manufactured according to the specific structure of a part, and after fine processing, the slices can be placed in a vacuum heating furnace for diffusion connection. Other materials such as cold spray additive and ultrasonic additive also face the problem of poor additive efficiency.
In contrast, friction additive has a great potential for improving solid-phase additive efficiency. However, in the existing friction additive manufacturing technology, heat is generated mainly by friction during solid-phase bonding, and in order to generate enough heat, a large multidirectional load is often required to be applied, so that the flexibility and additive efficiency of friction additive manufacturing are reduced, and the manufacturing of large and complex parts is not facilitated.
Disclosure of Invention
The technical problem is as follows: the invention aims to provide a hot wire friction micro-forging-based additive manufacturing device and method, and solves the problems that the existing friction additive manufacturing has low additive efficiency, large applied load in the additive process, poor manufacturing flexibility and is not beneficial to manufacturing large-scale complex parts.
The technical scheme is as follows: in order to solve the technical problems, the invention adopts the following technical scheme:
in one aspect, an embodiment of the present invention provides an additive manufacturing apparatus based on hot wire friction micro-forging, including a workbench including a substrate, and a friction stir device, an induction heating device, and a wire feeding device located in the workbench; the stirring and friction device is positioned above the substrate, and the induction heating device is connected with the stirring and friction device; the wire feeding device is positioned above the stirring friction device; the stirring friction device comprises a servo motor and a stirring piece; the stirring piece is driven by a servo motor to rotate, press down, lift and translate; a through hole is formed in the center axis of the stirring piece, and the wire feeding device feeds wires through the through hole of the stirring piece; the lower end face of the stirring piece is provided with a centrifugal flow guide fan blade and a protective shaft shoulder, and the protective shaft shoulder is positioned on the outer side of the centrifugal flow guide fan blade; one end of the centrifugal flow guide fan blade is connected with the protective shaft shoulder, and the other end of the centrifugal flow guide fan blade extends to the through hole; centrifugal diversion grooves are formed between adjacent centrifugal diversion fan blades.
Preferably, the induction heating device comprises an induction coil and a power supply, the power supply is connected with the induction coil, and the stirring piece is positioned in the inner cavity of the induction coil.
Preferably, the additive manufacturing device based on hot wire friction micro-forging further comprises a shielding gas device, the shielding gas device is connected with the friction stir device, and the stirring piece and the induction coil are both located in the shielding gas released by the shielding gas device.
Preferably, the protective gas device comprises a cover body and a gas source, the cover body is connected with the friction stir device, and the gas source introduces inert gas into an inner cavity of the cover body.
Preferably, the radial thickness of the protective shaft shoulder is 1-3 mm.
Preferably, the stirring member is made of a conductive material.
On the other hand, the embodiment of the invention also provides an additive manufacturing method based on hot wire friction micro-forging, which comprises the following steps:
step 10), opening an induction heating device, heating a stirring piece to be 0.45-0.95 times of the melting point of the wire, and keeping the stirring head at a constant temperature by controlling power supply parameters in the induction heating device;
step 20), starting the stirring friction device and the workbench, adjusting the stirring piece to a processing area, and keeping a rotating state;
step 30), starting the wire feeding device, adjusting the wire feeding speed, and ensuring that the wire can be heated to the temperature close to that of the stirring piece after passing through the through hole in the axis of the stirring piece;
step 40), controlling the workbench or the stirring piece to enable the stirring piece to travel along a preset path on the substrate to perform additive manufacturing;
and 50) after the additive manufacturing of one layer is finished, lifting the stirring head, and repeating the step 40) to perform additive manufacturing of the next layer until the additive manufacturing of the additive layer is finished.
Preferably, the additive manufacturing method based on hot wire friction micro-forging further includes: and opening the protective gas device to enable the heated part of the whole working area to be placed in the protective atmosphere.
Preferably, the width variation of the additive layer is achieved by replacing stirring elements of different diameters.
Preferably, the wires and the through holes of the stirring piece are in clearance fit, and the change of the material increase efficiency is realized by replacing the wires with different diameters.
Has the advantages that: compared with the prior art, the additive manufacturing device and method based on hot wire friction micro-forging, disclosed by the invention, plasticize the wire material by introducing induction heat, so that the requirement of a system on friction heat production is reduced, the additive manufacturing efficiency is improved, the manufacturing flexibility is increased, and the additive manufacturing device and method are particularly suitable for solid-phase additive manufacturing of large-scale complex parts.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
fig. 2 is a bottom view of a stirring head according to an embodiment of the present invention.
The figure shows that: the device comprises a stirring piece 1, a through hole 101, a centrifugal guide vane 102, a centrifugal guide groove 103, a protective shaft shoulder 104, an induction heating device 2, wires 3, a wire feeding device 4, a substrate 5 and an additive layer 6.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1 and fig. 2, an additive manufacturing apparatus based on hot wire friction micro-forging of the present embodiment includes a workbench including a substrate 5, and a friction stir device, an induction heating device 2, and a wire feeding device 4 located in the workbench. The stirring and friction device is positioned above the substrate 5, and the induction heating device 2 is connected with the stirring and friction device. The wire feeder 4 is located above the friction stir device. The friction stir device comprises a servo motor and a stirring piece 1. The stirring part 1 is driven by a servo motor to rotate, press down, lift and translate. The central axis of the stirring piece 1 is provided with a through hole 101, and the wire feeding device 4 feeds wires through the through hole 101 on the axis of the stirring piece 1. The lower end face of the stirring part 1 is provided with centrifugal guide vanes 102 and a protective shaft shoulder 104, and the protective shaft shoulder 104 is positioned outside the centrifugal guide vanes 102. One end of the centrifugal guide vane 102 is connected with the protective shaft shoulder 104, and the other end extends to the through hole 101.
Centrifugal guide grooves 103 are formed between adjacent centrifugal guide vanes 102.
In the above embodiment, the end surface of the stirring element 1 includes the through hole 101, the centrifugal guide vane 102, the centrifugal guide groove 103, and the protective shoulder 104. The centrifugal diversion trench 103 is a concave cambered surface. The stirring bar 1 is cylindrical. The wire feeder 4 feeds wire through the through hole 101. The lower end surface of the stirring piece 1 is provided with a centrifugal diversion trench 103 and a protective shaft shoulder 104. During the feeding of the wire 3 from the central through hole 101 of the stirring member 1 by the wire feeder 4, the wire 3 is heated by heat conduction and radiation from the stirring member 1 and induction heat from the induction coil, so that the wire 3 has reached a plasticized state when it reaches the lower end face of the stirring member 1. At this time, under the thrust of the wire feeder 4 and the high-speed rotation of the stirring member 1, the plasticized wires 3 are squeezed between the end of the stirring member and the substrate or the previous additive layer, so that the end of the stirring member 1 generates friction and stirring effects on the plasticized wires, and in addition, the flow guiding structure of the end of the stirring member, the plasticized wires 3 can be uniformly dispersed below the stirring member 1 and form metallurgical bonding with the substrate or the previous additive layer. In the process, the centrifugal diversion trench 103 can promote the wires 3 fed from the central through hole 101 of the stirring piece 1 to be rapidly transferred to the lower part of the whole stirring piece 1, so that the subsequent wire feeding can be carried out smoothly without blockage of the through hole 101. The protective shaft shoulder 104 is positioned outside the centrifugal diversion trench 103 to play a role in restraining and ensure that the wires 3 at the center do not overflow when being transferred outwards. The stirring piece 1 can rotate, press down, lift and move in a translation way under the driving of a servo motor. The worktable can do linear or curvilinear motion under the drive of the servo motor.
According to the method, the stirring piece is enabled to run along a preset route at a certain speed on the surface of the substrate while rotating at a high speed by controlling the stirring friction device and the workbench, and additive manufacturing is carried out. The plasticized wire is dispersed under the friction and forging action of the stirring piece and is metallurgically bonded with the previous additive layer or the substrate to form a compact solid-phase additive structure. According to the invention, the filament is plasticized by introducing induction heat, so that the requirement of a system on friction heat production is reduced, and the flexibility of friction stir additive manufacturing is increased.
Preferably, the induction heating device 2 comprises an induction coil and a power supply, the power supply is connected with the induction coil, and the stirring part 1 is positioned in the inner cavity of the induction coil. Heating the stirring part 1 by using an induction coil: high-frequency alternating current is introduced into the induction coil through the power supply, and induction current and induction heat are generated inside the stirring piece 1 through electromagnetic induction. By adjusting the power supply parameters, the heating temperature of the stirring element 1 can be controlled. The induction coil needs to move along with the stirring piece 1 to ensure that the relative position of the two does not change.
Preferably, the additive manufacturing device based on hot wire friction micro-forging further comprises a shielding gas device, the shielding gas device is connected with the workbench, and the stirring piece 1 and the induction coil are both located in the shielding gas released by the shielding gas device. The protective gas device comprises a cover body and a gas source, the cover body is connected with the friction stir device, and the gas source introduces inert gas into the inner cavity of the cover body. Inert gas can be introduced into the heating zone by means of a shielding gas device. When the additive metal is easy to oxidize at the processing temperature, a protective gas device is required to be arranged to ensure that the whole heating area is in the protective atmosphere.
Preferably, the radial thickness of the protective shaft shoulder 104 is 1-3 mm. The protective shoulder 104 serves to prevent the plasticized metal from escaping if the radial thickness of the protective shoulder is too small to be protected. If the radial thickness of the protective shoulder is too great, this can result in difficulties in distributing the plasticized metal evenly beneath the stirring element.
The additive manufacturing method implemented by the additive manufacturing device comprises the following steps:
and step 10), opening the induction heating device 2, heating the stirring part 1 to 0.45-0.95 time of the melting point of the wire 3, and keeping the stirring part 1 at a constant temperature by controlling power supply parameters in the induction heating device 2. The stirring member 1 is made of a conductive material.
And 20) starting the friction stir device and the workbench, adjusting the stirring piece 1 to the processing area, and keeping the rotation state. The rotating speed of the stirring head 1 is 100-1000 rpm. When the additive metal is metal with high heat conductivity such as aluminum, magnesium, copper, iron and the like, the higher rotating speed is 400-1000 rpm; when the additive metal is metal with low heat conductivity such as titanium, the rotating speed needs to be low and is 100-500 r/m.
And step 30), starting the wire feeding device 4, adjusting the wire feeding speed, and ensuring that the wires 3 can be heated to the temperature close to the stirring head 1 after passing through the through hole 101 in the axis of the stirring piece 1. By controlling the wire feeding speed, the wire 3 can be heated to a plasticized state at the end of the stirring member 1 by induction heat and heat conduction and radiation of the stirring member. If necessary, a current heating device can be applied to the wire to rapidly plasticize the wire: the two ends of the stirring piece are respectively provided with the electric brush, and current is supplied, so that the current flows through the wire to generate heat and resistance heat to heat.
And step 40) controlling the workbench or the stirring piece to enable the stirring piece 1 to travel on the substrate 5 along a preset path to perform additive manufacturing. The running speed of the stirring piece is equal to the wire feeding speed and the cross section area of the wire/the cross section area of the additive layer. The workbench is controlled to move, or the stirring piece 1 is controlled to move, or the workbench and the stirring piece 1 move relatively, so that the stirring piece 1 can walk on the substrate 5 along a preset path.
And step 50), after the additive manufacturing of one layer is finished, lifting the stirring piece 1, and repeating the step 40) to perform additive manufacturing of the next layer until the additive manufacturing is finished.
Through the steps, the material increase efficiency of friction material increase can be improved, the manufacturing flexibility is increased, and the method is particularly suitable for solid-phase material increase manufacturing of large-scale complex parts.
Preferably, the additive manufacturing method based on hot wire friction micro-forging further includes: and opening the protective gas device to enable the heated part of the whole working area to be placed in the protective atmosphere. When the additive metal is low-melting-point metal such as aluminum, magnesium and alloy thereof, protective gas can be omitted. When the additive metal is high-melting-point metal such as copper, titanium, iron and the like, protective gas is required to be used. The shielding gas is typically an inert gas.
In the aforementioned method, it is preferable that the width variation of the additive layer is achieved by replacing stirring elements 1 of different diameters. When the layer width needing material increase is larger, a stirring piece with a larger diameter is adopted. When the width of the layer needing additive is smaller, a stirring piece with a smaller diameter is adopted. If the width of the additive layer is extremely large, additive can be realized in a multi-pass parallel mode.
In the above method, preferably, the wire 3 is in clearance fit with the axial through hole of the stirring member 1. The variation of the additive efficiency is achieved by varying the diameter of the axial through hole 101 of the stirring member 1 and the diameter of the wire 3 matched therewith. When the diameter of the wire 3 is large, the additive efficiency is high, and when the diameter of the wire 3 is small, the additive efficiency is low.
Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.