36 results about "Melt pool" patented technology

The invention discloses a selective melting beam shaping and residual stress regulation cooperation method and system, and belongs to the technical field of selective melting additive manufacturing. The method comprises the steps that slicing data of a to-be-formed part are obtained, and characteristic parameters of all areas are analyzed; light beam spot parameters are adjusted in real time through a dynamic light beam shaping module based on the characteristic parameters; in the forming process, stress associated data of a molten pool and a heat affected zone are collected through a multi-dimensional stress monitoring module; the cooperative control unit analyzes the data based on a preset correlation model and judges stress abnormity; if yes, light spot parameter adjustment and stress regulation and control operation are synchronously controlled; and subsequent forming parameters are corrected through a closed-loop algorithm. The system comprises corresponding function modules and a process database. According to the method, light beam shaping and residual stress regulation are coordinated, the residual stress of parts is effectively reduced, deformation and cracking are reduced, the forming precision and the production efficiency are both considered, the process stability is improved, and the adaptation range of materials and complex structures is widened.

A schlieren system for in-situ / online monitoring of spatter in a large-area melt pool is provided, including a parallel light generation part, a parallel light deflection part, and an image acquisition part. The system can monitor spatter and other physical phenomena in the melt pool in a process of multi-layer printing and adjust a monitored area during an experiment to expand a monitored range. A reflector group composed of a plurality of plane mirrors is arranged, such that an optical path can be kept away from powder and dust areas, avoiding interference between the schlieren system and inherent devices inside a build chamber. Communication between a laser path controller and an optical path deflecting mirror galvanometer motor controller is established to automatically control the plane mirrors to change the monitored area, automatically track the melt pool, and realize online monitoring.

The invention relates to the technical field of solid waste harmless and recycling equipment, in particular to a gradient temperature pyrolysis-melting vitrification integrated treatment device and process for red mud. According to the device, an electromagnetic heating rotary kiln pyrolysis section and an electrode melting section are directly coupled with a material transfer device through high-temperature atmosphere isolation. The process comprises the following steps: granulating red mud, a reducing agent and a flux, feeding into a rotary kiln of which the temperature is accurately controlled by multiple groups of electromagnetic induction coils in a partitioned manner, and sequentially completing dehydration, selective reduction and iron particle polymerization to produce gt; high-temperature pyrolysis slag at 1000 DEG C; the pyrolysis slag directly falls into an electric melting pool to complete melting and iron-slag liquid phase separation under absolute isolation of reducing atmosphere and oxidizing atmosphere by the device, and pig iron and a stable glass body are respectively obtained. Through the design of'hot slag direct melting 'and'energy closed loop', the problems of high energy consumption and complex flow of the traditional process are solved, and efficient recovery of iron resources in the red mud and thorough harmless and high-valued utilization of the residues are realized.

An automated method of measuring, monitoring and recording candle burn performance using vision system automation. The method includes timed candle flame height measurement consisting of a camera using image bursts. Recording in a database with a unique identifier barcode for each candle and corresponding wick to identify and record candle data with a date and time stamp. Audio-Visual alerts for flame callouts less than ½ inch or greater than 2 inches and 3″. Documenting any extinguished candles / wicks (mid and / or end of life). Candle Temperature Measurement is performed every 2 hours (depending on burn type and cycle), which includes wax melt pool temperature (with callouts for temperatures reaching and / or exceeding 250 deg C.) and container side wall temperature. Candle Picture is performed at the mid and end of life, and the sustainer position is tracked to determine wick migration.

The application discloses a kind of safety automatic control flow's casting equipment, including melt pool, aluminium water inlet pool and pump chamber, melt pool is connected to aluminium water inlet pool by aluminium water channel in furnace, pump chamber is connected with aluminium water inlet pool by bottom inlet channel, impeller is provided in pump chamber, aluminium water outlet channel is connected with aluminium water steady flow pool above pump chamber, aluminium water steady flow pool bottom is provided with steady flow pool flow eye, steady flow pool flow eye is connected with outlet flow groove, steady flow pool flow eye outer end is provided by the plug head for plugging steady flow pool flow eye;Method, S1: melt raw material in melt pool, obtain aluminium water;S2: aluminium water flows into to pump chamber, then flows into to aluminium water steady flow pool;S3: aluminium water in aluminium water steady flow pool, flow into to outlet flow groove;S4: aluminium water in outlet flow groove flows into to corresponding aluminium piece casting tray, corresponding need to be manufactured aluminium piece can be obtained;Effect: method structure is novel, steady flow pool flow eye and melt pool are not directly communicated, increase insurance for aluminium casting safety, guarantee safety.

A method for preparing a magnesium alloy tissue engineering scaffold with a smooth inner surface by laser powder bed fusion (LPBF) is provided. The method includes: step S1: scanning a porous scaffold, and selecting the densest filling scan parameters, where the scanning includes a single-pass contour scan and a single-pass filling scan; step S2: optimizing a contour scan strategy according to the densest filling scan parameters; step S3: acquiring a corresponding melt pool dimension, and adjusting a spot compensation value based on the optimized contour scan strategy; and step S4: preparing a magnesium alloy tissue engineering scaffold based on the contour scan strategy and the adjusted spot compensation value. The method eliminates powder adhesion and sagging defects inside the complex porous structure that severely affect inner surface roughness and scaffold performance, thereby the pore connection, fatigue and corrosion resistance will be improved greatly.

The application discloses an aluminum-based 3D printing melt pool behavior intelligent analysis method based on image recognition and relates to the technical field of additive manufacturing process monitoring. The method comprises the following steps: acquiring a time sequence image sequence of a melt pool region in an aluminum-based 3D printing process, performing a pixel-level gray gradient direction coding operation on the time sequence image sequence, and generating a melt pool boundary flow direction feature map; based on the melt pool boundary flow direction feature map, extracting a geometric deformation parameter of a melt pool contour, and mapping the geometric deformation parameter to a printing coordinate space to generate melt pool deformation field distribution data; according to the melt pool deformation field distribution data, tracking displacement vectors of melt pool boundary points between adjacent frames, and calculating a melt pool surface oscillation frequency through the displacement vectors to obtain melt pool oscillation characteristic quantities; and performing phase matching on the melt pool oscillation characteristic quantities and preset melt pool stability criteria to output a melt pool behavior state marker.

The invention belongs to the technical field of liquid metal 3D printing, and particularly relates to a jet flow control system for melt impact, which comprises an upper cavity device, a vacuumizing system, a gas supply system, a pressure monitoring device, a main controller and an upper computer, an upper cavity pressure gauge is mounted at the upper part of the upper cavity device and is used for monitoring the gas pressure in the upper cavity device in real time; a nozzle is arranged on the lower portion of the upper cavity device, the gas supply system is communicated with the upper cavity device, the vacuumizing system is communicated with the upper cavity device, and the upper computer, the upper cavity pressure gauge, the gas supply system and the vacuumizing system are all in communication connection with the main controller. The upper computer is used for inputting an operation instruction to the main controller, so that the main controller controls the gas supply system and the vacuumizing system based on the operation instruction and the gas pressure; through non-mechanical on-off control of gas pressure, rapid opening and closing of jet flow are achieved, it is guaranteed that the solidification and forming process of a molten pool is controllable, and a series of problems caused by a mechanical switch are avoided.

This invention discloses a method for fine-grained billet preparation with low extrusion ratio and synergistic annealing of difficult-to-deform high-γ′ phase superalloys, comprising the following steps: raw material purification and batching preparation – vacuum induction melting – electron beam melting pretreatment – ​​initial molten pool establishment and stabilization melting – homogenization treatment – ​​hot extrusion and annealing heat treatment. The method utilizes electron beam droplet melting directional solidification technology to prepare difficult-to-deform superalloy ingots with continuous columnar crystal structure. Taking advantage of the significantly superior dislocation storage capacity of columnar crystals compared to traditional equiaxed crystals, and combining low extrusion ratio billet preparation with subsequent precision recrystallization annealing, this method effectively avoids the problems of easy cracking, uneven microstructure, and high cost in high extrusion ratio dynamic recrystallization processes, breaking the stringent limitations of traditional processes on the lower limit of the extrusion ratio. Compared with traditional high extrusion ratio billet preparation processes, the material yield is increased from 60%–75% to 80%–90%, an increase of 15%–25%, significantly reducing the extrusion cracking scrap rate and improving the overall microstructure consistency of the bars.

Method for depositing materials in a substrate (12), comprising: arranging a first section of a substrate in a vertically downward direction; directing an energy beam (16) from below the first section upwards towards the first section; forming a melt pool (26) in the substrate (12) using the directed energy beam (16), wherein the melt pool (26) is formed such that it is directed vertically downwards in the first section;and directing a particle stream (20) from below the first section upwards towards the first section, wherein at least some of the particles (20A) are configured to rise in the melt pool (26) towards the substrate (12), wherein the particles (20) are made of a different material than the substrate (12), and wherein the method further comprises: solidifying the melt pool (26) after the desired quantity of particles (20) has been dispersed in the melt pool (26) and the desired particles (20A) have risen in the melt pool (26) towards the substrate (12), and forming a coating on the substrate (12) which is a metal matrix composite coating with a desired degree of porosity near the unmelted sections of the substrate (12).

The invention discloses a laser powder feeding additive manufacturing device and method for an Nb-Si intermetallic compound composite material, and relates to the technical field of high-temperature structural material additive manufacturing. The method solves the problems that according to an existing method for preparing the Nb-Si intermetallic compound composite material through the laser directional energy deposition technology, due to the fact that the local temperature gradient is huge and thermal stress is too high, a formed part is prone to cracking, deformation and composition segregation, and a complete and compact component cannot be obtained. In an inert gas protection environment, dynamic preheating and post-heating heat preservation are carried out on the front area and the rear area of a laser molten pool through combination of overall preheating of a substrate and a local auxiliary heating device synchronously moving with a laser deposition head, and the temperature gradient of a deposition area is strictly controlled to be below a safety threshold value through infrared temperature measurement closed-loop control; and finally, stress release is completed through programmed slow cooling. The method is used for crack-free and high-quality near-net forming manufacturing of Nb-Si-based intermetallic compound composite material components for high-temperature structures in the aerospace field.

The utility model discloses an auxiliary device for testing the density of an asphalt core sample, which comprises a wax melting pool used for melting a solid wax block to form a wax liquid and maintaining the wax liquid in a molten state; the at least one clamp is positioned in the wax melting pool and is used for grabbing an asphalt core sample; the control arm is rotationally mounted on the side wall of the wax melting pool, one end of the control arm penetrates through the side wall of the wax melting pool and extends into the wax melting pool to be connected with the clamp, the control arm is provided with a control mechanism, and the control mechanism is used for controlling the clamp to clamp the asphalt core sample. The fixture is arranged in the wax melting pool, the fixture is controlled through the control arm and the control mechanism, wax liquid coating of an asphalt core sample can be rapidly completed by rotating the control arm, and wrist injury of a tester can be effectively avoided.

The application discloses an extrusion forming device for aluminum alloy profile preparation, which comprises a sliding outer cylinder, a feeding pipe is communicated with the bottom of the side surface of the sliding outer cylinder, a fixed screw sleeve is fixedly connected with the side surface of the sliding outer cylinder, a moving ring is fixedly connected with the inner wall side surface of the sliding outer cylinder at a position above the feeding pipe, a connecting frame is fixedly connected with the bottom of the moving ring, an extrusion base is fixedly connected with the bottom of the connecting frame, a straightening pipe is fixedly connected with the top of the extrusion base, the extrusion base is arranged in the inside of a melting pool and is slidably connected with the inner wall side surface of the melting pool, and the sliding outer cylinder is threadedly connected with the top of a driving assembly through the fixed screw sleeve. Before extrusion forming is carried out, the raw material is firstly introduced, the equipment base supports and fixes the melting pool and the driving assembly, the extrusion forming device is preset at a position above the melting pool, and the raw material enters the inside of the melting pool to be melted.

A method of manufacturing a 3D object, the method comprising: providing a powder layer of powder particles; building up a new layer of the 3D object by directing a beam of radiation towards the powder layer to melt the powder particles at predetermined positions to build up the new layer of the 3D object on re-solidification; and forming a pore in the new layer at a preselected position by using a beam of radiation to form and subsequently collapse a melt pool so as to trap gas as a pore in or below the new layer at the preselected position on re-solidification.

The utility model relates to the technical field of fly ash treatment equipment, and discloses a fly ash melting treatment device which comprises a feeding section and a melting section, the feeding section comprises a stock bin, a first feeding channel, a second feeding channel and a pusher, the first feeding channel is vertically arranged, the second feeding channel is inclined, the first feeding channel is connected with a discharge port of the stock bin and the second feeding channel, the second feeding channel is provided with a first end and a second end lower than the first end, and the pusher is arranged at the first end in the second feeding channel; the melting section comprises a third feeding channel, a molten pool and a combustor, a fly ash feeding opening is formed in the position, close to the bottom, of the molten pool, and the second end is connected with the fly ash feeding opening through the third feeding channel; combustors are installed on the two opposite side walls of the molten pool, the molten pool is provided with a smoke outlet and a liquid fly ash overflow opening, and when the combustors work, the temperature of the area, close to the top wall, in the molten pool ranges from 1400 DEG C to 1500 DEG C. The fly ash treatment device is suitable for treating fly ash with the flowing temperature below 1350 DEG C, and energy consumption and equipment cost can be reduced.

Computer-implemented systems and methods are described herein for determining additive manufacturing parameters in a simulation. Input data regarding a product to be generated via additive manufacturing and a beam diameter are received. Based on the input data, a characteristic dimension is determined. The beam diameter is normalized based on the characteristic dimension. Additive manufacturing parameters, such as penetration depth and absorptivity, are determined based on the normalized beam diameter and experimentally-determined trends. The manufacturing of the product is then simulated according to the additive manufacturing parameters.

The invention provides an additive manufacturing high-temperature alloy printing piece and a preparation method thereof, and relates to the technical field of additive manufacturing, and the preparation method comprises the following steps: performing selective laser melting forming treatment on high-temperature alloy powder to obtain a deposition-state additive manufacturing high-temperature alloy printing piece with a layered crystal structure; wherein in the step of selective laser melting forming treatment, by controlling technological parameters, the lap joint rate of a molten pool is made to be 30%-60%, and the ratio of the height to the width of the molten pool is 0.7-1.4; the layered crystal structure is lt; 001gt, 001gt; an orientation zone and lt; 110gt, 110gt; the orientation areas are alternately arranged in the direction perpendicular to the laser scanning direction and are of a layered structure continuously extending in the laser scanning direction. The result is determined through the lap joint rate of the molten pool; 110gt, 110gt; forming an orientation area, lt; 110gt, 110gt; and an orientation area has a higher Taylor factor, so that larger shear stress is generated in the deformation process, deformation twin crystals can be activated, and the plasticity of an additive manufacturing high-temperature alloy printing piece can be improved.

The invention discloses a monitoring method and device for a metal additive manufacturing molten pool, a terminal, a storage medium and a computer program product, and the method comprises the steps: carrying out the training of a dual-network model composed of improved YOLOv7 and improved U-net based on the historical image data of the metal additive manufacturing molten pool, and obtaining a needed image monitoring model; based on the current image data of the metal additive manufacturing molten pool, current monitoring data of the metal additive manufacturing molten pool are obtained through the image monitoring model; and according to the current monitoring data of the metal additive manufacturing molten pool, control parameters of the metal additive manufacturing molten pool are adjusted, so that the forming quality of a metal structural part of the metal additive manufacturing molten pool is improved. According to the scheme, the dual-network model composed of the YOLOv7 and the U-net is adopted to conduct cooperative processing on the image data of the molten pool to obtain the monitoring data of the molten pool, accurate control over the molten pool is achieved, and implementation of the high-quality forming target of the metal additive manufacturing process is improved.

The present invention relates to a comprehensive framework for real-time quality monitoring, control, and optimization in additive manufacturing (AM) processes, notably Laser Powder Bed Fusion (LPBF). The system combines high-speed imaging, sophisticated mathematical modeling, and machine learning techniques to analyze track geometric attributes and melt pool characteristics, including width, height, depth, wetting angles, and hatch spacing. Novel dimensionless wetting shape factors are introduced to characterize track profiles, and equations for acute and obtuse contact angles are derived, with additional exploration of the interplay between powder layer thickness and track dimensions through quadratic equations describing hyperbolic relationships.

Detectors are situated along a tilted optical axis to receive optical radiation from a work surface. Variations in the received optical power are used to estimate a work surface positional along a work surface axis. The received optical power can be emitted from the work surface and an estimated temperature of the work surface used to adjust the received optical power. One or two single element detectors or a linear detector can be used. A position of a focused spot produced from the received optical power at the linear detector can be used to assess work surface axial position.

Systems and methods for additive manufacturing are described. In some embodiments, a method of controlling a weld height in an additive manufacturing process includes determining a desired melt pool width based, at least in part, on a desired weld height; selectively activating one or more laser energy sources based, at least in part, on the desired melt pool width; and melting a portion of a layer of material on a build surface via exposure to laser energy from the one or more activated laser energy sources to form a melt pool on the build surface having the desired melt pool width. Systems and methods to the use of staggered laser energy sources are also described.

A computer-implemented method (3000) for measuring a thickness e of a batch of material (2005) floating on a melt pool (2006) in an electrical glass or stone melting furnace (1002). The method takes, as input data, a time scale temperature map M [T] set (I3000) of a batch (2005) of material, a range R [Ts] of expected values of a stabilization temperature Ts of the batch (2005), and a threshold of a change in temperature over time. The method provides, as output data, a spatial distribution (O3000) of the thickness of the batch (2005) over its surface.

The application belongs to the technical field of glass fiber production and manufacturing, and relates to an ultrafine fiber manufacturing device and manufacturing process, which comprises a melting pool connected with a homogenizing pool through a first solution mass self-flowing channel, the top surface of the melting pool near the first solution mass self-flowing channel is provided with a bubble discharging slope, the two side walls of the homogenizing pool are connected with a drawing channel through a second solution mass self-flowing channel, a plurality of drawing sieve plate combinations are arranged on a single drawing channel, the top of the melting pool, the homogenizing pool and the drawing channel is provided with a heating and supplementing layer, and the bottom of the homogenizing pool is provided with a residue discharging system. The first solution mass self-flowing channel is used to realize automatic shunting and eliminate solution cross contamination by using the mass difference of the solution itself, meanwhile, the second solution mass self-flowing channel of the two side walls of the homogenizing pool further screens the solution entering the drawing channel, so that only the high-quality homogenized glass flows into the drawing link, and the bubble discharging slope guides the bubbles on the surface of the glass solution to gather along the slope surface and float out by using the inclined structure.

Detectors are situated along a tilted optical axis to receive optical radiation from a work surface. Variations in the received optical power are used to estimate a work surface positional along a work surface axis. The received optical power can be emitted from the work surface and an estimated temperature of the work surface used to adjust the received optical power. One or two single element detectors or a linear detector can be used. A position of a focused spot produced from the received optical power at the linear detector can be used to assess work surface axial position.

The present application relates to solid waste harmless and resource equipment technical field, specifically is a kind of red mud gradient temperature pyrolysis-melting vitrification integrated processing device and process.The device directly couples electromagnetic heating rotary kiln pyrolysis section and electrode melting section by high-temperature atmosphere isolation and material transfer device.Process is: after granulating red mud, reducing agent and flux, send into the rotary kiln by multiple electromagnetic induction coil partition precise temperature control, complete dehydration, selective reduction and iron particle polymerization in turn, output >1000 ℃ high-temperature pyrolysis slag;Pyrolysis slag is directly dropped into electric melting pool to complete melting and iron-slag liquid separation under the absolute isolation of reducing atmosphere and oxidizing atmosphere in the device, respectively obtain pig iron and stable glass body.The present application solves the problem of high energy consumption and complex process of traditional process by "hot slag direct melting" and "energy closed loop" design, realizes efficient recovery of iron resources in red mud and complete harmless and high-value utilization of residue.

An apparatus may include one or more processors, and memory comprising machine-readable instructions that, when executed by the one or more processors, cause the apparatus to receive a plurality of images of a particulate on a build plane of an additive manufacturing system captured by a camera while one layer of the particulate is exposed to an energy beam of the additive manufacturing system, and combine the plurality of images to generate an image of a melt pool trajectory of the one layer of the particulate.

Control unit (9) for an additive manufacturing system (100) for emitting a heat source (L) to a feed material (53) which is fed to a workpiece (13) in order to melt the feed material (53) and solidify it into grains, and to form an object (12) by stacking the grains on the workpiece (13), wherein the control unit (9) controls a power of the heat source (L) on the one hand and / or a raster speed of the heat source (L) and a material feed speed of the feed material (53) on the other hand, based on melt bath state measurement information, wherein the melt bath state measurement information is a value which is obtained by measuring a state of a melt bath, wherein the melt bath is the molten feed material (53), wherein the control unit (9) comprises: a processing condition output unit (93) which outputs values ​​of the power of the heat source (L), the raster speed of the heat source (L) and the material feed rate to the additive manufacturing system (100); a heat source power addition unit (94) which adds a predetermined addition value (ΔP) to the power of the heat source (L) output by the processing condition output unit (93) and outputs the power of the heat source (L) to which the predetermined addition value (ΔP) has been added to the processing condition output unit (93) when: (i) a melt pool state error is less than a predetermined threshold, wherein the melt pool state error is a difference between a melt pool target state information and the melt pool state measurement information, where the melt pool target state information is a target value of the melt pool state; (ii) the power output value of the heat source (L) output by the processing condition output unit (93) is less than a maximum power (Pmax) of the heat source (L); and (iii) the scanning speed of the heat source (L) is less than a maximum scanning speed (Fmax); a melt pool state error calculation unit (91) which calculates the melt pool state error from a recorded image of the state of the melt pool; a velocity addition unit (95), which: a raster speed change value (ΔF) is added to the raster speed output by the processing condition output unit (93), and a material feed rate change value (ΔW) is added to the material feed rate output by the processing condition output unit (93); and outputs the raster speed, to which the raster speed change value (ΔF) is added, and the material feed rate, to which the material feed rate change value (ΔW) is added, to the processing condition output unit (93), wherein the raster speed change value (ΔF) is a change value of the raster speed and depends on the predetermined addition value (ΔP), wherein the material feed rate change value (ΔW) is a change value of the material feed rate and depends on the raster speed change value (ΔF), a speed adjustment unit (96) which, based on the addition of the predetermined addition value (ΔP) to the power of the heat source (L) and the addition of the raster speed change value (ΔF) and the material feed speed change value (ΔW) to the raster speed and material feed speed respectively, adjusts the raster speed of the heat source (L) and the material feed speed based on the melt pool condition error.

The invention is suitable for the technical field of 3D printing molten pool monitoring and control, and provides a 3D printing molten pool temperature calibration method based on regional gray scale and temperature modeling. Comprising the steps of substrate partition division (dividing into at least nine calibration areas in a checkerboard mode), exposure time optimization (adjusting gray scale data to normal distribution based on Shapio-Wilk inspection), multi-source data acquisition (synchronous acquisition by a monochromatic camera and a pyrometer), gray scale preprocessing (background elimination and normalization formula), and multi-source data acquisition (synchronous acquisition by a single-color camera and a pyrometer). According to the method, accurate calibration of the temperature of the molten pool is realized through six core steps of partition model construction (exponential function fitting) and dynamic temperature calibration (real-time position matching and model calling); according to the method, through regional fine treatment and parameter optimization, the temperature calibration error is reduced from 10% or above to 5% or below, the equipment cost is reduced by 60% or above, and synchronous display of the molten pool morphology and the temperature field is supported.

The application provides a kind of high-power laser fuse pool synchronous intelligent shaping method of deposition, it is related to additive manufacturing technical field, comprising: S1 according to the parameters of the piece to be printed, using three-dimensional software to model;S2 determine the material and forming process parameters of the piece to be printed;S3 utilize high-power laser to the material of current layer is deposited with fuse, adopts CCD camera to melt pool topography and surrounding topography real-time three-dimensional contour scanning obtains the topography, depth, width and temperature information of melt pool;S4 according to the optimal heating path of small power laser obtained by identification algorithm, and real-time control the working power, working position and working time of small power laser;S5 using small power laser according to heating path to melt pool is remelted and shaped;S6 repeat steps S3-S5, complete the additive manufacturing process of each layer, until the printed piece is obtained.The application can reduce splashes, control the defects of printed piece and stabilize melt pool.

A laser welding method according to one embodiment comprises: a process of forming a first melt pool by alternately shining a laser light onto an end portion of a first wire-shaped element and an end portion of a second wire-shaped element, wherein the first melt pool spans the end portion of the first wire-shaped element and the end portion of the second wire-shaped element, and the second wire-shaped element is adjacent to the first wire-shaped element; and a process of shining the laser light onto the first melt pool. The process of shining the laser light onto the first melt pool comprises: defining a central region of the first melt pool as a starting point for the laser light irradiation and moving an irradiation position of the laser light away from the starting point, such that the irradiation position moves away gradually or stepwise while rotating around the starting point.