CN113351865A - Electrostatic field assisted laser additive manufacturing device and method - Google Patents

Electrostatic field assisted laser additive manufacturing device and method Download PDF

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Publication number
CN113351865A
CN113351865A CN202010144162.8A CN202010144162A CN113351865A CN 113351865 A CN113351865 A CN 113351865A CN 202010144162 A CN202010144162 A CN 202010144162A CN 113351865 A CN113351865 A CN 113351865A
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China
Prior art keywords
electrode
clad
electrostatic field
working electrode
substrate
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CN202010144162.8A
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Chinese (zh)
Inventor
欧阳文泰
徐子法
焦俊科
张文武
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Ningbo Institute of Material Technology and Engineering of CAS
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Ningbo Institute of Material Technology and Engineering of CAS
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Priority to CN202010144162.8A priority Critical patent/CN113351865A/en
Publication of CN113351865A publication Critical patent/CN113351865A/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE 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
    • B33Y10/00Processes of additive manufacturing
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE 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
    • B33Y30/00Apparatus for additive manufacturing; Details thereof or accessories therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00Aspects linked to processes or compositions used in powder metallurgy
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/25Process efficiency

Abstract

The application discloses an electrostatic field assisted laser additive manufacturing device and method, wherein the device at least comprises a power supply, a working electrode pair and a laser; the working electrode pair is respectively connected with the positive electrode and the negative electrode of the power supply; and the laser performs laser material increase processing on the matrix to be clad between the working electrode pairs under the action of an electrostatic field formed by the working electrode pairs. According to the electrostatic field-assisted laser additive manufacturing device, in the laser additive machining process, the working electrode can provide an electrostatic field for a substrate to be clad between the working electrode pair, and under the action of the electrostatic field, the elimination of pores in a workpiece and the regulation and control of the internal organization trend of the workpiece in the manufacturing process can be realized.

Description

Electrostatic field assisted laser additive manufacturing device and method
Technical Field
The application belongs to the technical field of material preparation, and in particular relates to an electrostatic field assisted laser additive manufacturing device and an electrostatic field assisted laser additive manufacturing method.
Background
The laser additive manufacturing technology is based on the idea of calculus, adopts the modes of laser layered scanning and superposition molding to increase materials layer by layer, and converts a digital model into a three-dimensional solid part. The traditional metal part molding and manufacturing adopts a casting method, solid metal is melted into liquid and poured into a casting mold with a specific shape and is solidified and molded, the process is multiple, the mold cost is high, the manufacturing period from design to part manufacturing is long, and the defects of no contribution to parts with complex inner cavity structures are overcome. Relative to the traditional casting technology, the laser additive manufacturing technology is a manufacturing method of material accumulation from bottom to top. However, with the development of materials and laser additive manufacturing technology and the increasingly harsh use environment of parts, higher requirements are put on the quality of the laser additive manufactured parts, such as turbine blades and other workpieces which need to bear alternating loads, and the mechanical properties of the coating are seriously affected by residual air holes.
In the related art, the lorentz force is formed by compounding the current and the magnetic field to assist laser additive manufacturing, but the regulation and control difficulty of the internal structure and performance trend of the workpiece is high, and further improvement of the mechanical performance of the workpiece is also limited.
Disclosure of Invention
In order to solve the technical problems, the application provides an electrostatic field assisted laser additive manufacturing device and method, and further solves the problems that the internal composition and performance of a workpiece tend to be difficult to regulate and control and the like due to the limitations and defects of the related technology at least to a certain extent.
In order to achieve the purpose, the technical scheme adopted by the application is as follows:
according to an aspect of the present application, there is provided an electrostatic field assisted laser additive manufacturing apparatus, the apparatus comprising at least
A power supply, a working electrode pair, and a laser;
the working electrode pair is respectively connected with the positive electrode and the negative electrode of the power supply;
and the laser performs laser material increase processing on the matrix to be clad between the working electrode pairs under the action of an electrostatic field formed by the working electrode pairs.
In an exemplary embodiment of the invention, the apparatus further comprises:
an electrode clamping component connected with at least one electrode in the working electrode pair and used for controlling the position movement of the electrode;
and/or an electrode insulating part is positioned on the surface of at least one electrode in the working electrode pair and is used for separating the electrode from the substrate to be cladded on the supporting part.
In an exemplary embodiment of the invention, the apparatus further comprises:
the supporting part is used for placing a substrate to be clad;
the protective gas system is connected with the laser and used for providing protective gas for the laser additive machining process;
the supporting part, the laser, the electrode clamping part and the protective gas system are all connected with a control system;
preferably, the control system is an industrial personal computer or a computer.
According to an aspect of the application, there is provided an electrostatic field assisted laser additive manufacturing method, the method at least comprising:
connecting the working electrode pair with the positive electrode and the negative electrode of a power supply respectively;
oppositely arranging the working electrode pairs on two sides of the substrate to be clad;
and after the power supply is switched on, carrying out laser material increase processing on the matrix to be clad under the action of the electrostatic field formed by the working electrode pair.
In one exemplary embodiment of the invention, there is insulation between at least one electrode of the pair of working electrodes and the substrate to be clad.
In an exemplary embodiment of the present invention, during the laser additive machining of the substrate to be clad, the method further includes:
adjusting the position of the working electrode pair;
preferably, an included angle formed between the working electrode pair and the substrate to be clad is adjustable at will.
In an exemplary embodiment of the invention, the adjusting the position of the working electrode pair includes:
adjusting the positions of the positive electrode and the negative electrode in the working electrode pair to form electrostatic fields with the same area and opposite directions;
varying the distance between the pair of working electrodes to vary the electrostatic field strength between the pair of working electrodes;
or at least one electrode in the working electrode pair is rotated relative to the substrate to be clad.
In an exemplary embodiment of the invention, the oppositely disposing the pair of working electrodes on two sides of the substrate to be clad includes:
the working electrode pairs are oppositely arranged on two side surfaces parallel to the horizontal plane of the matrix to be cladded so as to form an electrostatic field vertical to the horizontal plane of the matrix to be cladded;
or the working electrode pairs are oppositely arranged on two side surfaces vertical to the horizontal surface of the matrix to be cladded so as to form an electrostatic field parallel to the horizontal surface of the matrix to be cladded.
In an exemplary embodiment of the invention, the at least one electrode having a gap with the substrate to be clad comprises:
arranging a dielectric layer between the electrode and the substrate to be cladded;
or clamping the electrode by an electrode clamping system to ensure that a gap exists between the electrode and the matrix to be clad;
wherein the dielectric layer is made of at least one of the insulating materials including alumina, insulating paper and insulating tape.
In an exemplary embodiment of the present invention, after the power is turned on, the laser additive processing process is performed on the substrate to be clad under the action of the electrostatic field formed by the working electrode pair, including:
irradiating the added material conveyed to the matrix to be clad by using laser beams to form a cladding layer on the matrix to be clad;
the process conditions comprise: the power supply is any one of a direct current power supply, an alternating current power supply and a pulse power supply; the laser beam is either a flat-top beam or a gaussian beam.
The utility model provides an electrostatic field assists laser vibration material disk device's beneficial effect lies in:
through the oppositely arranged working electrode pairs, in the process of performing laser material increase processing on the matrix to be clad positioned between the working electrode pairs, an electrostatic field is provided for the matrix to be clad, the deformation and the aggregation of molten liquid generated on the matrix to be clad can be controlled, the internal organization trend of the workpiece can be regulated and controlled, the pores in the workpiece can be eliminated, and the mechanical property of the workpiece can be improved;
furthermore, the device also comprises an electrode clamping component, and the position movement of the electrode is not limited, so that the position of the electrode can be randomly changed in space according to requirements, and the direction of an electrostatic field of a matrix to be clad, the included angle between the electrostatic field and the matrix to be clad and the intensity of the electrostatic field are changed, so that the finally obtained workpiece can be optimal in the direction needing to bear the load; meanwhile, the electrode clamping component is the same as the electrode clamping component, insulation between at least one electrode and a substrate to be clad can be controlled by arranging the electrode insulation component, so that no current is generated in the workpiece, the coarsening of the grain structure of the workpiece material caused by joule heat is avoided, the mechanical property of the workpiece is further improved, inconvenience and potential safety hazards caused by the generation of too high heat can be avoided, and the operation safety of the device is high.
The electrostatic field assisted laser additive manufacturing method has the beneficial effects that:
through the electrostatic fields provided by the working electrode pairs oppositely arranged on the two sides of the substrate to be clad, the deformation and the aggregation of molten liquid generated on the substrate to be clad can be controlled, the regulation and the control of the internal organization trend of the workpiece are realized, the pores in the workpiece can be eliminated, and the mechanical property of the workpiece is improved;
furthermore, insulation exists between at least one electrode and a matrix to be clad, so that no current is generated in the workpiece, the coarsening of the grain structure of a workpiece material caused by joule heat is avoided, the mechanical property of the workpiece is further improved, and inconvenience and potential safety hazard for operation due to excessive heat generation are avoided; meanwhile, due to the fact that the electrode which is not in contact with the matrix to be clad exists, the position movement of the electrode is not limited, therefore, the position of the electrode can be changed at will in the space in the laser material increase processing process according to requirements, the direction of an electrostatic field of the matrix to be clad, the included angle between the electrostatic field and the matrix to be clad and the intensity of the electrostatic field are changed, and the direction of the load borne by the finally obtained workpiece is optimal.
Drawings
Fig. 1 is a schematic diagram of an electrostatic field assisted laser additive manufacturing apparatus according to the present application;
fig. 2 is a schematic diagram of an electrostatic field assisted laser additive manufacturing apparatus according to the present application;
fig. 3 is a flow chart of an electrostatic field assisted laser additive manufacturing method of the present application;
FIG. 4 is a schematic diagram illustrating a relative position relationship between a working electrode pair and a substrate to be clad according to an embodiment of the present disclosure;
FIG. 5 is a schematic illustration of an exemplary working electrode pair arrangement of FIG. 4 herein;
FIG. 6 is a schematic diagram illustrating a relative position relationship between a working electrode pair and a substrate to be clad according to an embodiment of the present disclosure;
FIG. 7 is a schematic illustration of an exemplary working electrode pair arrangement of FIG. 6 of the present application;
FIG. 8 is a schematic diagram illustrating a relative position relationship between a working electrode pair and a substrate to be clad according to an embodiment of the present disclosure;
FIG. 9 is a schematic processing diagram of a laser additive manufacturing method of the present application;
FIG. 10 is a scanning electron microscope image of a cross section of a cladding layer without the assistance of an electrostatic field according to the present application;
FIG. 11 is a gold phase diagram of a cross-sectional optical microscope of a cladding layer without the assistance of an electrostatic field according to the present application;
FIG. 12 is a scanning electron microscope photograph of a cross section of a cladding layer of the present application with the aid of an electrostatic field;
FIG. 13 is a gold phase diagram under an optical microscope of a cross section of a cladding layer with the aid of an electrostatic field according to the present application.
List of parts and reference numerals:
1 a first electrode; 2 a second electrode;
101 a power supply; 3, cladding the substrate;
4 cladding the head; 5, cladding layer;
501 adding material bundles; 502 a laser beam;
6 a support part; 7, a laser;
701 laser output head; 703 feeding powder head;
9 an electrode holding member; 10 a shielding gas system;
11 a control system; 12 electrode insulation parts.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known technical solutions have not been shown or described in detail to avoid obscuring aspects of the present application.
The terms "a," "an," "the," and "said" are used to indicate the presence of one or more elements/components/etc.; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.; the terms "first" and "second", etc. are used merely as labels, and are not limiting on the number of their objects.
Unless otherwise specified, the raw materials in the examples were purchased commercially and used without treatment; the used instruments and equipment adopt the use parameters recommended by manufacturers.
In the examples, scanning electron microscope pictures of the cross section of the cladding layer with/without the assistance of an electrostatic field were obtained using a FEI Quanta 250FEG type scanning electron microscope.
In the related technology, the Lorentz force is formed by compounding current and a magnetic field to assist laser additive manufacturing, a power supply needs to be in contact with a workpiece, so that the direction of the Lorentz force is difficult to change randomly in space along with requirements, and simultaneously, the generated Joule heat causes coarsening of a grain structure in the workpiece material, so that the mechanical property is limited, and when the heat is high, adverse effects are caused on operability and safety.
Based on this, the present application first provides an electrostatic field assisted laser additive manufacturing apparatus, and first, an implementation principle of the embodiments of the present application is explained:
under the action of electrostatic field, the positively charged liquid drops are distributed at the position close to the negative pole of the electric field, and the negatively charged liquid drops are distributed at the position close to the positive pole of the electric field. Under the action of an electrostatic field, the liquid drops are stretched, and meanwhile, due to mutual attraction between positive charges and negative charges, the similar liquid drops are combined under the action of a dipole force to form larger liquid drops. Based on the principle, in a molten pool generated on a substrate in the laser additive machining process, liquid drops stretch and deform under the action of an electrostatic field and gather, so that internal pores are eliminated, the growth direction of crystal grains is changed due to the change of the liquid drops in the process, a columnar crystal area is disturbed to form isometric crystals (the crystal grains with smaller size difference in each direction are isometric crystals, namely the isometric crystals), and thicker isometric crystals are refined to form finer isometric crystals, so that the mechanical property of a finally obtained workpiece is changed.
As shown in fig. 1, the electrostatic field assisted laser additive manufacturing apparatus of the present application may include at least: a power supply 101, a pair of working electrodes (including a first electrode 1 and a second electrode 2), a laser 7;
wherein, the working electrode pair is respectively connected with the anode and the cathode of the power supply 101; the laser 7 is used for performing laser additive machining on the matrix 3 to be clad between the working electrode pairs under the action of an electrostatic field formed by the working electrode pairs.
Through the working electrode pairs oppositely arranged on the two sides of the matrix 3 to be cladded, an electrostatic field is provided for the matrix 3 to be cladded in the laser additive machining process of the matrix 3 to be cladded, the deformation and the aggregation of molten liquid generated on the matrix 3 to be cladded can be controlled, the internal tissue trend of a workpiece can be regulated, the pores in the workpiece can be eliminated, and the mechanical property of the workpiece can be improved.
In this embodiment, the apparatus may further comprise a support 6 for placing the substrate 3 to be clad.
In this embodiment, in order to insulate at least one electrode of the working electrode pair from the substrate to be clad in the apparatus, in some possible embodiments, the apparatus of the present application may further include an electrode clamping member 9 connected to at least one electrode of the working electrode pair for controlling the position movement of the electrode, and based on the electrode clamping member 9, the position movement of the electrode is not limited, so that the position of the electrode may be arbitrarily changed in space according to requirements during the laser additive machining process, thereby changing the electrostatic field direction of the substrate to be clad, the included angle between the electrostatic field and the substrate to be clad, and the electrostatic field strength, so that the finally obtained workpiece may reach the optimum direction in which the workpiece needs to bear the load.
In some possible embodiments, the apparatus of the present application may further include an electrode insulating member 12 located on at least one electrode surface of the working electrode pair for separating the electrode from the substrate 3 to be clad, and the electrode insulating member 12 may be, for example, a member composed of an insulating material, such as alumina, insulating paper, insulating tape, or the like.
For example, fig. 2 shows an electrostatic field assisted laser additive manufacturing apparatus according to an exemplary embodiment of the present application, and as shown in fig. 2, the apparatus includes a support 6, a laser cladding system (including a laser output head 701 electrically connected to a laser 7 (not shown in fig. 7), a powder feeding head 703 connected to the powder feeding head (not shown in fig. 7)) located above the support 6, a power source 101, and a working electrode pair (including a first electrode 1 and a second electrode 2).
Wherein, the laser beam emitted by the laser output head 701 irradiates the added material beam synchronously output to the base body 3 to be clad by the powder feeding head 703, and forms a cladding layer 5 on the base body 3 to be clad; the power supply 101 is a direct current power supply, an alternating current power supply or a pulse power supply, and the laser light source can be laser light of various wave bands such as infrared light, visible light, ultraviolet light and the like, and can be selected according to actual requirements; the output laser beam is a flat-top beam or a gaussian beam, which is not particularly limited in this application.
In addition, the electrostatic field assisted laser additive manufacturing apparatus of the present application may further include a shielding gas system 10, connected to the laser 7, for providing a shielding gas for the laser additive manufacturing process; wherein, the introduced protective gas is common protective gas such as argon, nitrogen and the like.
In the present embodiment, the support portion 6, the laser 7, the electrode clamping member 9, and the shielding gas system 10 are all connected to the control system 11;
the control system 11 is an industrial personal computer or a computer, or other control systems are selected according to actual requirements, which is not particularly limited in this application.
In addition, the electrostatic field assisted laser additive manufacturing apparatus of the present application may further include a powder feeder for conveying the additive material onto the substrate 3 to be clad, and of course, the additive material may be placed on the substrate to be clad by other methods.
According to the electrostatic field assisted laser additive manufacturing device, the working electrode pairs which are oppositely arranged on the two sides of the supporting part are utilized, and the laser cladding system is used for carrying out laser additive processing on the matrix to be clad on the supporting part under the action of the electrostatic field formed by the working electrode pairs, so that the deformation and the aggregation of molten liquid generated on the matrix to be clad can be controlled, the regulation and control of the internal organization trend of a workpiece are realized, the pores in the workpiece can be eliminated, and the mechanical property of the workpiece is improved; furthermore, at least one electrode in the working electrode pair can be controlled to move by the electrode clamping system for clamping the electrode pair, so that the electrostatic field strength between the working electrode pair, the included angle between the electrostatic field and the substrate to be clad and/or the electrostatic field direction can be conveniently changed, and therefore, the position of the electrode can be freely changed in space according to requirements in the laser additive machining process, the electrostatic field direction of the substrate to be clad, the included angle between the electrostatic field and the substrate to be clad and the electrostatic field strength are changed, and the finally obtained workpiece can be optimal in the direction needing to bear load. In addition, the insulation between at least one electrode and the matrix to be clad can be controlled through the electrode clamping component, so that no current is generated in the workpiece, the coarsening of the grain structure of the workpiece material caused by joule heat is avoided, the mechanical property of the workpiece is further improved, the inconvenience and potential safety hazard caused by the generation of too high heat are avoided, and the operation safety of the device is high.
According to an aspect of the present application, there is provided an electrostatic field assisted laser additive manufacturing method, and fig. 3 shows a flowchart of an electrostatic field assisted laser additive manufacturing method according to an embodiment of the present application, and as shown in fig. 3, the electrostatic field assisted laser additive manufacturing method according to the present embodiment may include at least the following steps:
step S310, the working electrode pair is connected to the positive electrode and the negative electrode of the power supply, respectively.
In this embodiment, a working electrode pair (including the first electrode 1 and the second electrode 2) is connected to the positive electrode and the negative electrode of the power supply for providing the electrostatic field, wherein the material of the working electrode pair is selected from conventional conductive electrode materials, including but not limited to aluminum, copper, silver, gold, and other conductive materials. The power supply adopts a direct current power supply, an alternating current power supply or a pulse power supply, and the corresponding power supply can be selected according to the actual working condition, which is not specially limited in the application.
And S320, oppositely arranging the working electrode pairs on two sides of the substrate to be clad.
In this embodiment, since the working electrode pairs are oppositely disposed, an electrostatic field can be provided for the substrate 3 to be clad, which is located between the working electrode pairs, and optionally, the working electrode pairs can provide an electrostatic field for the entire substrate of the substrate 3 to be clad; optionally, the working electrode pair may also provide an electrostatic field for a part of the substrate 3 to be clad, and may be selected according to actual preparation requirements depending on the positions of the working electrode pair at both sides of the substrate 3 to be clad.
In some possible embodiments, pairs of working electrodes are arranged opposite each other on both sides parallel to the horizontal plane of the substrate 3 to be clad, so as to form an electrostatic field perpendicular to the horizontal plane of the substrate 3 to be clad. Specifically, as shown in fig. 4, the substrate 3 to be clad is horizontally placed on the support 6, the first electrode 1 is disposed at an upper side position parallel to the horizontal plane of the substrate 3 to be clad, the second electrode 2 is disposed at a lower side position parallel to the horizontal plane of the substrate 3 to be clad, and the first electrode 1 and the second electrode 2 are disposed opposite to each other, so that an electrostatic field perpendicular to the horizontal plane of the substrate 3 to be clad is formed between the substrates 3 to be clad (since the positive and negative electrodes of the first electrode 1 and the second electrode are not indicated, the direction of the electrostatic field is not indicated in fig. 4).
Further, there may be insulation between at least one electrode and the substrate to be clad in the working electrode pair, for example, a gap may be left between the electrode and the substrate to be clad, for example, an insulating dielectric layer may be disposed between the substrate to be clad and the electrode, and the like, which is not particularly limited in this application. Based on this, in the process of carrying out work piece processing through the device, work piece itself does not have the electric current to produce, has avoided joule heat to lead to the grain structure coarsening of work piece material, further promotes the mechanical properties of work piece, also can not bring inconvenience and potential safety hazard for the operation because of producing too high heat yet.
For example, fig. 5 shows an exemplary working electrode pair arrangement schematic diagram of fig. 4 of the present application, and referring to fig. 5, a first electrode 1 of the working electrode pair is loaded on a cladding head 4 in a laser cladding system, and the cladding head 4 is disposed above a substrate 3 to be clad, and a second electrode 2 of the working electrode pair is disposed opposite to and below the substrate 3 to be clad, so as to form an electrostatic field perpendicular to the substrate 3 to be clad. Optionally, the first electrode 1 can rotate along with the rotation of the cladding head 4 (as shown in fig. 5), and can also be clamped by the electrode clamping system and move along with the electrode clamping system; the second electrode 2 can be directly fixed below the substrate 3 to be clad and contacted with the substrate 3 to be clad, a dielectric layer can be arranged between the second electrode 2 and the substrate 3 to be clad, the second electrode 2 can be clamped by an electrode clamping system, a gap exists between the second electrode 2 and the substrate 3 to be clad, and the like. The material of the dielectric layer between the substrate 3 to be clad and the electrode is at least one selected from insulating materials including alumina, insulating paper, and insulating tape, which is not particularly limited in this application.
It should be noted that fig. 5 is only an exemplary illustration of the arrangement of the working electrode pair in the present application, and in the case of ensuring that at least one electrode in the working electrode pair does not contact the substrate 3 to be clad, the loading and clamping manners of the first electrode 1 and the second electrode 2 may be both, and the loading and clamping manners of the first electrode 1 and the second electrode may be interchanged, of course, other clamping manners may be also possible, and the clamping manner of the working electrode pair in the present application is not particularly limited.
Based on this, there is insulation between at least one electrode and the matrix to be clad, resulting in no current generation of the workpiece itself, avoiding the coarsening of the grain structure of the workpiece material caused by joule heat, further improving the mechanical properties of the workpiece, and avoiding inconvenience and potential safety hazard for operation due to the generation of excessive heat.
In some possible embodiments, the pairs of working electrodes are oppositely disposed on both sides perpendicular to the horizontal plane of the substrate 3 to be clad, so as to form electrostatic fields parallel to the horizontal plane of the substrate 3 to be clad, for example, the electrostatic field direction is along the molten pool forming direction, against the molten pool forming direction, and the like. Specifically, as shown in fig. 6, the substrate 3 to be clad is horizontally placed on the support 6, the first electrode 1 is disposed at a left position perpendicular to a horizontal plane of the substrate 3 to be clad, the second electrode 2 is disposed at a right position perpendicular to a horizontal plane of the substrate 3 to be clad, and the first electrode 1 and the second electrode 2 are disposed opposite to each other, so that an electrostatic field parallel to the horizontal plane of the substrate 3 to be clad is formed between the substrates 3 to be clad.
For example, fig. 7 is a schematic diagram of an exemplary arrangement of working electrode pairs of fig. 6 of the present application, and referring to fig. 7, the first electrode 1 and the second electrode 2 are clamped and fixed by an electrode clamping system 9 and respectively located at the left and right sides of the substrate 3 to be cladded, so as to form an electrostatic field parallel to the horizontal plane of the substrate 3 to be cladded. Optionally, both the first electrode 1 and the second electrode 2 can be clamped 9 by an electrode clamping system, and a gap is reserved between the first electrode and the substrate 3 to be clad (as shown in fig. 7); optionally, at least one of the first electrode 1 and the second electrode 2 may also be fixed on the substrate 3 to be clad; alternatively, at least one of the first electrode 1 and the second electrode 2 may be fixed on the substrate 3 to be clad, and a dielectric layer is disposed between the electrode and the substrate 3 to be clad; of course, the clamping and fixing manner of the electrode and the positional relationship between the electrode pair and the substrate 3 to be clad can be selected according to actual working requirements, and the application includes but is not limited to the clamping manner of the electrode pair.
Of course, fig. 7 is only an exemplary illustration of the arrangement of the working electrode pairs of the present application, and it is ensured that an electrostatic field parallel to the horizontal plane of the substrate 3 to be clad is formed between the working electrode pairs while ensuring that at least one electrode of the working electrode pair is not insulated from the substrate 3 to be clad.
Based on this, there is insulation between at least one electrode and the matrix to be clad, resulting in no current generation of the workpiece itself, avoiding the coarsening of the grain structure of the workpiece material caused by joule heat, further improving the mechanical properties of the workpiece, and avoiding inconvenience and potential safety hazard for operation due to the generation of excessive heat.
Further, in the process of performing laser material additive machining on the substrate to be clad, the intensity of an electrostatic field between the pair of working electrodes, an included angle between the electrostatic field and the substrate to be clad, and/or the direction of the electrostatic field can be changed by adjusting the position of at least one electrode in the pair of working electrodes.
With continued reference to fig. 7, during the laser additive machining, the working electrode pair may also be moved and rotated in any spatial direction (as indicated by an arrow) by each axis of the electrode clamping system 9 to change the intensity of the electrostatic field formed by the working electrode pair, the included angle between the electrostatic field and the substrate to be clad, and/or the direction of the electrostatic field; fig. 8 shows a schematic diagram that an included angle between an electrostatic field formed by a working electrode pair and a substrate to be clad is 30 °, however, fig. 8 is only an example, and an included angle between an electrostatic field formed by a working electrode pair and a substrate to be clad can be arbitrarily adjusted, for example, the included angle may be 20 °, 45 °, 55 °, 70 °, 120 °, and so on.
Optionally, the positions of the positive electrode and the negative electrode in the pair of the working electrodes can be changed to form electrostatic fields with the same area and opposite directions; alternatively, the distance between the pair of working electrodes can be varied to vary the electrostatic field strength between the pair of working electrodes; alternatively, at least one electrode of the pair of electrodes may be offset with respect to the substrate 3 to be clad; optionally, at least one electrode of the pair of electrodes may also be rotated relative to the substrate 3 to be clad; of course, the position of the working electrode pair can be adjusted by at least two of the above modes according to actual working requirements. The specific arrangement position of the working electrode pair is not specially limited, and the electrostatic field can be provided for the matrix to be clad.
Based on this, the electrostatic field direction of the matrix 3 to be clad, the included angle between the electrostatic field and the matrix to be clad or the intensity of the electrostatic field can be changed at will in space by changing the position of the working electrode pair, so that the deformation and aggregation of molten liquid generated on the matrix 3 to be clad can be controlled, the internal tissue tendency of the final workpiece can be further changed, the actually required mechanical property of the workpiece can be obtained, and the direction of the finally obtained workpiece for bearing the load can be optimized; meanwhile, the deformation and aggregation of molten liquid generated on the substrate 3 to be clad in the preparation process are controlled, the pores in the workpiece can be eliminated, and the mechanical property of the final workpiece is further improved.
And S330, after the power supply is switched on, performing laser material increase processing on the matrix to be clad under the action of the electrostatic field formed by the working electrode pair.
In this embodiment, after the power is turned on, under the action of the electrostatic field formed by the working electrode pair, the laser additive processing process is performed on the substrate 3 to be clad, and the laser additive processing process includes:
irradiating the added material conveyed to the matrix to be clad by utilizing laser beams, and forming a cladding layer on the matrix to be clad. Specifically, a laser output head in the laser cladding system emits a laser beam to irradiate the added material synchronously conveyed to the substrate 3 to be clad by a powder feeding head in the laser cladding system, so as to form a cladding layer 5 on the substrate 3 to be clad. The laser light source can be laser of various wave bands such as infrared light, visible light, ultraviolet light and the like, and materials including but not limited to metal powder can be selected and added according to actual needs.
For example, as shown in fig. 9, which is a schematic diagram of a laser additive manufacturing method according to an exemplary embodiment of the present application, a laser beam 502 emitted from a cladding head 4 in a laser cladding system irradiates a metal powder beam 501 synchronously delivered to a substrate 3 to be clad by the cladding head 4 to form a cladding layer 5 on the substrate 3 to be clad; compared with the molten metal in the cladding area without the assistance of the electrostatic field, the molten metal in the cladding area is stretched and gathered under the assistance of the electrostatic field formed by oppositely arranging electrode pairs at two sides of the matrix 3 to be clad. Under the auxiliary action of the electrostatic field, the deformation and the aggregation of the molten liquid can be controlled, the internal organization trend of the workpiece can be regulated, the pores in the workpiece can be eliminated, and the mechanical property of the workpiece can be improved.
According to the electrostatic field assisted laser additive manufacturing method, the electrostatic fields provided by the working electrode pairs oppositely arranged on the two sides of the substrate to be clad are free of current and magnetic fields, and the deformation and aggregation of molten liquid generated on the substrate to be clad can be controlled through the electrostatic fields, so that the internal organization trend of the workpiece can be regulated and controlled, the pores in the workpiece can be eliminated, and the mechanical property of the workpiece can be improved; furthermore, insulation exists between at least one electrode and a matrix to be clad, so that no current is generated in the workpiece, the coarsening of the grain structure of a workpiece material caused by joule heat is avoided, the mechanical property of the workpiece is further improved, and inconvenience and potential safety hazard for operation due to excessive heat generation are avoided; meanwhile, due to the fact that the electrode which is not in contact with the matrix to be clad exists, the position movement of the electrode is not limited, therefore, the position of the electrode can be changed at will in space according to requirements in the laser additive machining process, the direction of an electrostatic field of the matrix to be clad, the included angle between the electrostatic field and the matrix to be clad and the intensity of the electrostatic field are changed, and the direction of a finally obtained workpiece which needs to bear load is optimal.
Example 1
In this embodiment, a dc power supply is used as a power supply for providing a field, a direction along the formation of a molten pool is used as an applying direction of an electrostatic field, a fiber laser with a wavelength of 1064nm is used as a light source for laser additive manufacturing, and a laser beam is a gaussian beam. The specific process is as follows:
step 1, selecting 304 stainless steel as a matrix to be clad, wherein the size of the matrix is 200mm multiplied by 10mm, and the added material (cladding powder) is 316L stainless steel metal powder with the particle size of 75-150 mu m;
step 2, preprocessing a matrix to be melted and metal powder, polishing the matrix to be melted by abrasive paper, then removing oil stains by absolute ethyl alcohol, drying, and drying the metal powder;
step 3, oppositely arranging the working electrode pairs at two sides vertical to the horizontal plane of the substrate to be cladded, and arranging insulating paper between the working electrode pairs and the substrate to be cladded, wherein the distance between the working electrode pairs is 3 cm;
step 4, connecting a direct current power supply with the working electrode pair, so that the working electrode close to the starting end of the laser additive manufacturing process is connected with the positive electrode of the power supply, and the working electrode far away from the starting end of the laser additive manufacturing process is connected with the negative electrode of the power supply (so as to form an electrostatic field along the forming direction of a molten pool);
and 5, an electrostatic field assists the laser additive manufacturing process, argon is introduced through a protective gas system to serve as protective gas, a power supply is started and adjusted to 400V, and a program for laser additive manufacturing starts to run, wherein the process parameters are as follows: the diameter of a light spot is 1mm, the rotating speed of a rotary table of the powder feeder is 1r/min, the laser power is 800w, and the laser scanning speed is 3 mm/s.
And 6, after the program for laser additive manufacturing is operated, turning off the power supply.
Example 2
Example 2 the raw materials, process parameters, etc. for laser additive manufacturing were the same as in example 1, except that no electrostatic field assistance was used.
The samples of the clad substrates in examples 1 and 2 were cut along the scanning direction, polished and then observed for characterization, and fig. 10-11 show the scanning electron microscope image and the gold phase image under the optical microscope of the clad layer section without the assistance of the electrostatic field in example 2, and fig. 12-13 show the scanning electron microscope image and the gold phase image under the optical microscope of the clad layer section with the assistance of the electrostatic field in example 1, respectively. Comparing fig. 10 and fig. 12, it can be seen that the number of pores in the cross section of the cladding layer is significantly reduced and the structure formed after the solidification of the molten pool is denser with the assistance of the electrostatic field (the intensity of the electrostatic field is 133V/cm); comparing fig. 11 with fig. 13, the cladding layer can have a large amount of columnar crystals and equiaxed crystals with larger crystal grains without the assistance of the electrostatic field; after the electrostatic field with the intensity of 133V/cm is assisted, the grains are disturbed in the growth process due to the deformation and polymerization of metal droplets in the molten pool, columnar crystals cannot be formed in the molten pool, and smaller isometric crystals are formed, so that the structure is more uniform, and a compact cladding layer with few pore defects is obtained.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

Claims (10)

1. An electrostatic field assisted laser additive manufacturing device is characterized by at least comprising a power supply, a working electrode pair and a laser;
the working electrode pair is respectively connected with the positive electrode and the negative electrode of the power supply;
and the laser performs laser material increase processing on the matrix to be clad between the working electrode pairs under the action of an electrostatic field formed by the working electrode pairs.
2. The apparatus of claim 1, further comprising:
an electrode clamping component connected with at least one electrode in the working electrode pair and used for controlling the position movement of the electrode;
and/or an electrode insulating part is positioned on the surface of at least one electrode in the working electrode pair and used for separating the electrode from a matrix to be cladded.
3. The apparatus of claim 2, further comprising:
the supporting part is used for placing a substrate to be clad;
the protective gas system is connected with the laser and used for providing protective gas for the laser additive machining process;
the supporting part, the laser, the electrode clamping part and the protective gas system are all connected with the control system.
4. An electrostatic field assisted laser additive manufacturing method is characterized by at least comprising the following steps:
connecting the working electrode pair with the positive electrode and the negative electrode of a power supply respectively;
oppositely arranging the working electrode pairs on two sides of the substrate to be clad;
and after the power supply is switched on, carrying out laser material increase processing on the matrix to be clad under the action of the electrostatic field formed by the working electrode pair.
5. The method of claim 4, wherein there is insulation between at least one electrode of the pair of working electrodes and the substrate to be clad.
6. The method of claim 4, further comprising, during the laser additive machining of the substrate to be clad:
adjusting the position of the working electrode pair;
preferably, the included angle between the working electrode pair and the substrate to be cladded is adjustable at will.
7. The method of claim 6, wherein said adjusting the position of the working electrode pair comprises:
exchanging the positions of the positive electrode and the negative electrode in the working electrode pair;
varying the distance between the pair of working electrodes;
rotating the working electrode pair relative to the substrate to be clad.
8. The method of any one of claims 4-7, wherein said positioning said pair of working electrodes opposite to each other on both sides of the substrate to be cladded comprises:
the working electrode pairs are oppositely arranged on two sides parallel to the horizontal plane of the matrix to be cladded so as to form an electrostatic field vertical to the horizontal plane of the matrix to be cladded;
or the working electrode pairs are oppositely arranged on two sides perpendicular to the horizontal plane of the matrix to be cladded so as to form an electrostatic field parallel to the horizontal plane of the matrix to be cladded.
9. The method of claim 5, wherein said insulating between said at least one electrode and said substrate to be cladded comprises:
arranging a dielectric layer between the electrode and the substrate to be cladded;
or clamping the electrode by an electrode clamping system to ensure that a gap exists between the electrode and the matrix to be clad;
wherein the dielectric layer is made of at least one of the insulating materials including alumina, insulating paper and insulating tape.
10. The method of claim 4, wherein the applying the laser additive machining process to the substrate to be clad under the action of the electrostatic field formed by the working electrode pair after the power is turned on comprises:
irradiating the added material conveyed to the matrix to be clad by using laser beams to form a cladding layer on the matrix to be clad;
preferably, the power supply is any one of a direct current power supply, an alternating current power supply and a pulse power supply; the laser beam is either a flat-top beam or a gaussian beam.
CN202010144162.8A 2020-03-04 2020-03-04 Electrostatic field assisted laser additive manufacturing device and method Pending CN113351865A (en)

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Application publication date: 20210907