CN110643996A

CN110643996A - Micro-rolling and ultrasonic-assisted laser cladding device

Info

Publication number: CN110643996A
Application number: CN201911111372.0A
Authority: CN
Inventors: 石永军; 冯子京; 王凯; 王淑尧; 程鸣; 张进
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2020-01-03

Abstract

The invention relates to a micro-rolling and ultrasonic-assisted laser cladding device, in particular to strengthening of the surface of a cladding layer. The device comprises a workbench, a fixed stop block, a workpiece, a first mechanical arm, a synchronous powder feeder, a laser, a micro-roller, a rotating device, an amplitude transformer, a second mechanical arm and an ultrasonic generator. The micro-rolling technology and the ultrasonic technology are used in an auxiliary mode during laser cladding, and the combination can eliminate the adverse effect caused by pure laser scanning to the maximum extent. In the micro rolling process, dendritic crystalline lenses generated when the cladding layer is cooled are crushed by micro rollers, so that the crystal structure is refined, and the generation of pores is effectively inhibited. The ultrasonic technology eliminates the residual tensile stress generated when the cladding layer is cooled, and effectively reduces the generation of cracks. The micro-rolling technology and the ultrasonic technology are applied to the laser cladding layer, so that the compactness, isotropy and other properties of the cladding layer are further improved.

Description

Micro-rolling and ultrasonic-assisted laser cladding device

Technical Field

The invention belongs to the technical field of surface engineering, and particularly relates to a micro-rolling and ultrasonic-assisted laser cladding device.

Background

The development of economy and the advancement of science and technology, people are urgently required to have higher performance and higher quality equipment, so that the parts are required to have better strength, rigidity and stability, and the surfaces of the parts are required to have better wear resistance, oxidation resistance and impact load resistance. Common preparation methods for improving the surface performance of parts comprise laser cladding, induction cladding, electroplating and the like, and the adopted cladding process has the advantages of thick coating, easiness in forming metallurgical bonding, high coating performance and the like. However, the cladding layer prepared by a single method has more defects, so that the method for making up the defects is a good idea.

The laser cladding is a technology for improving the surface performance of parts by forming a cladding layer after metal powder and the surfaces of the parts are melted at high temperature by utilizing laser beams. The laser cladding has the advantages of high heating speed, small heat affected zone, convenience in automation realization and the like, and is widely applied to the fields of aerospace, chemical engineering, machinery and the like. However, in the laser cladding process, due to the fact that laser beams are not uniformly distributed, temperature difference exists in different areas forming a molten pool, the cooling speed of the cladding layer is high, large residual stress is easily generated, anisotropic large dendritic crystals are formed in the cladding layer, and brittleness of the cladding layer is increased. In addition, the cladding layer generated by laser cladding is easy to generate defects such as cracks, bubbles and the like.

The micro-rolling technology is a preparation method for applying physical pressure to a cladding layer by rolling a micro roller on the surface of the cladding layer. The anisotropy in the material is improved through the plastic deformation of the material, and the micro-roller crushes dendritic crystalline lenses generated in the cladding layer into fine cross-shaped grains through the cooling cladding layer, so that the crystal structure is refined, and the generation of bubble cracks can be reduced.

However, the micro-rolling technology belongs to physical changes, has high requirements on the strength during rolling, is harsh on the shape of the surface of a part, and has no obvious effect on eliminating the residual stress in the cladding layer.

The ultrasonic technology is a series of physical actions generated when ultrasonic waves act on the surface of a part, so that the crystal structure can be refined, the residual stress formed in the cladding layer is eliminated, and the generation of cracks is reduced. At present, a large number of researches show that by adopting the ultrasonic vibration and laser cladding combined method, only ultrasonic vibration is introduced, so that although residual stress can be reduced and air holes and crack defects can be reduced, the density of a cladding layer is not improved; in some researches, the micro-rolling process is combined with laser cladding, and although the cladding density can be improved, the process can add new residual stress to a cladding layer.

Disclosure of Invention

The invention aims to solve the problems and provides a micro-rolling and ultrasonic-assisted laser cladding device which combines laser cladding, micro-rolling and ultrasonic technologies, can provide the compactness of a cladding layer, can reduce residual stress and reduce air holes and crack defects, thereby optimizing a single laser cladding process and improving the comprehensive performance of the laser cladding layer.

The invention adopts the following technical scheme: the device comprises a workbench, a fixed stop block, a workpiece, a first mechanical arm, a synchronous powder feeder, a laser, a micro-roller, a rotating device, an amplitude transformer, a second mechanical arm and an ultrasonic generator. The workbench is fixed on the ground, and the workpiece is fixed on the workbench through the fixed stop block; the synchronous powder feeder and the laser are connected to the first mechanical arm, and the synchronous powder feeder and the laser can move up and down and left and right under the drive of the first mechanical arm; the rotating device can drive the micro roller and the amplitude transformer to move up and down, left and right and horizontally rotate, and the micro roller and the amplitude transformer are fixed on the same platform; the rotating device is connected with the second mechanical arm; the amplitude transformer is connected with the ultrasonic generator. After the coaxial powder feeder scans, the micro-roller is driven by the second mechanical arm to micro-roll the cladding layer, and the amplitude transformer at a certain distance from the micro-roller is also driven by the mechanical arm to ultrasonically impact the micro-rolled cladding layer. The micro rolling technology can transform the larger dendrite generated during rapid cooling into a fine cross crystal, and can improve the compactness of the cladding layer. By adopting ultrasonic impact, the residual tensile stress generated by temperature gradient during cooling of the cladding layer and the compressive stress generated after micro rolling can be eliminated, the generation of cracks is reduced, and the integral service performance of the surface of the part is further improved.

The invention provides a device for micro-rolling and ultrasonic-assisted laser cladding. The working method mainly comprises the following steps:

(1) and cleaning and polishing the workpiece to be clad, and ensuring that the workpiece has uniform thickness and no corrosion on the surface.

(2) Fixing a workpiece on a workbench, controlling a first mechanical arm to the right side of the workpiece, and positioning a synchronous powder feeder right above the workpiece; and controlling the second mechanical arm to move to a certain distance right and right of the first mechanical arm, and suspending the micro roller at the moment to form a certain distance with the upper surface of the workpiece.

(3) And starting a laser and a synchronous powder feeder, controlling a first mechanical arm to begin cladding, then starting an ultrasonic generator on the right side, and controlling a second mechanical arm to move leftwards to begin rolling and ultrasonically impacting the cladding layer.

(4) According to the working requirement, cladding-rolling-ultrasonic vibration composite operation is carried out on the workpiece.

(5) And (5) closing the synchronous powder feeder and the laser, and closing the ultrasonic generator.

(6) Taking down the workpiece and cooling the workpiece in air.

In particular, the device needs to be carried out under the protection of argon gas in order to prevent the oxidation of the cladding surface during operation. The argon nozzle is connected with the synchronous powder feeder and is sprayed into a cladding area together with metal powder during cladding.

Particularly, the rolling force of the micro-roller is too small to crush dendritic crystalline lenses in the cladding layer, and the rolling force is too large to prevent the moving platform from moving normally. The rolling force of the micro-roller on the cladding layer is determined according to the morphology of the cladding layer and the material properties of the metal powder, and the rolling force can be realized by controlling the mechanical arm.

Particularly, in order to eliminate residual stress generated by laser cladding and micro rolling, the amplitude transformer needs to rotate 180 degrees when moving to the edge of a workpiece, and the amplitude transformer is ensured to follow the rear of the micro roller at any time.

The invention has the following advantages:

the micro-rolling technology and the ultrasonic technology are used in an auxiliary mode during laser cladding, and the adverse effect caused by pure laser scanning can be eliminated to the maximum extent through the technical combination. The micro-rolling technology is adopted, and the dendritic crystalline lens generated when the cladding layer is cooled is crushed by the micro-roller to be converted into fine cross-shaped crystals, so that the crystal structure is refined, and the generation of air holes is effectively inhibited. By adopting the ultrasonic technology, the residual tensile stress generated when the cladding layer is cooled can be eliminated, the generation of cracks is effectively reduced, and the residual stress generated when rolling is eliminated. The micro-rolling technology and the ultrasonic technology are simultaneously acted on the laser cladding layer, so that the compactness of the cladding layer is obviously improved, the residual stress is basically eliminated, the defects of cracks, air holes and the like are greatly reduced, the surface quality of the laser cladding layer is enhanced, and the comprehensive service performance of a workpiece is improved.

Drawings

The figure is the overall schematic diagram of the patent

Description of the symbols

1. The device comprises a workbench 2, a fixed stop block 3, a workpiece 4, a first mechanical arm 5, a synchronous powder feeder 6, a laser 7, a micro roller 8, a rotating device 9, an amplitude transformer 10, a second mechanical arm 11 and an ultrasonic generator.

Detailed Description

As shown in the figure, the invention relates to a micro-rolling and ultrasonic-assisted laser cladding device. The device comprises a workbench 1, a fixed stop 3, a workpiece 4, a first mechanical arm 5, a synchronous powder feeder 6, a laser 7, a micro roller 8, a rotating device 9, an amplitude transformer 10, a second mechanical arm 11 and an ultrasonic generator. In the figure, a workbench 1 is fixed on the ground, and a workpiece 3 is fixed on the workbench 1 through a fixed stop block 2; in the figure, a synchronous powder feeder 5 and a laser 6 are connected to a first mechanical arm 4, and the synchronous powder feeder 5 and the laser 6 can move up, down, left and right under the drive of the first mechanical arm; in the figure, the rotating device 6 can drive the micro roller 7 and the amplitude transformer 9 to move up and down, left and right and horizontally rotate, and the micro roller 7 and the amplitude transformer 9 are fixed on the same platform; the rotating device is connected with the 8 and the second mechanical arm 10; the horn 9 is shown connected to an ultrasonic generator 11.

The laser cladding process and apparatus using micro-rolling and ultrasonic assistance will be described below with the iron-based alloy M2 as the workpiece and the same iron-based alloy powder M2 as the cladding material. Wherein the size of the workpiece is 600mm multiplied by 400mm multiplied by 10 mm; the rated input voltage of the laser is 220V, the output power is 1000W, the wavelength is 1080mm, and the laser scanning speed is 600 mm/min; the cladding thickness is 0.6mm, and the diameter of a light spot is 4 mm; the power of the ultrasonic generator is 600W, and the frequency is 40 KHz; the pressure of the micro-roller to the workpiece is 100N.

The specific implementation is as follows:

(1) and (3) cleaning and polishing the workpiece by using a metal cleaning agent to ensure that the metal plate is flat and has no corrosion, and fixing the workpiece on the workbench.

(2) And controlling the first mechanical arm and the second mechanical arm to move to corresponding positions and setting corresponding parameters.

(3) And starting the ultrasonic generator, starting the laser and the synchronous powder feeder, and controlling the two mechanical arms to synchronously move leftwards at the speed of 10 mm/s.

(4) After the synchronous powder feeder moves to the left edge of the workpiece, the first mechanical arm is controlled to move longitudinally for 3mm and then move rightwards in parallel, and therefore the first cladding layer and the second cladding layer are guaranteed to have a lap joint rate of 1 mm; when the micro roller is rolled to the left side of the workpiece and suspended, the second mechanical arm is controlled to longitudinally move for 3mm and rotate the rotating device for 180 degrees, the amplitude transformer is always positioned behind the micro roller, the micro roller is positioned right left of the synchronous powder feeder, and then the second mechanical arm is controlled to translate right.

(5) And (5) repeating the step (4) until the cladding layer of the whole workpiece is finished.

(6) And after cladding is finished, all the switches are closed, and the two mechanical arms are moved to be away from the upper part of the workpiece.

(7) And taking down the workpiece, and cooling the workpiece in air.

The above-described embodiments are merely illustrative and not restrictive, and changes and additions to the above-described embodiments may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. A micro-rolling and ultrasonic-assisted laser cladding device comprises a workbench and a fixed stop block, wherein the workbench and the fixed stop block are used for placing and fixing workpieces; the synchronous powder feeder and the laser are positioned above the workpiece and controlled by the first mechanical arm, the synchronous powder feeder is used for uniformly spraying metal powder into a molten pool, and a device for providing argon gas is arranged between the synchronous powder feeder and the laser to prevent the surface of a cladding layer from being oxidized; the micro-roller and the amplitude transformer are positioned in the same module and controlled by a second mechanical arm, and the micro-roller rolls the cladding layer to improve the compactness of the cladding layer; the horn is coupled to an ultrasonic generator to generate ultrasonic vibrations to relieve internal stresses.

2. The micro-rolling and ultrasonic-assisted laser cladding apparatus according to claim 1, wherein a micro-rolling technique and an ultrasonic vibration technique are added during the laser cladding process.

3. The micro-rolling and ultrasonic-assisted laser cladding apparatus according to claim 1, wherein the second robotic arm controlled rotation means rotates 180 ° while moving to the edge of the workpiece to ensure that the horn is immediately behind the micro-roll at that time.