A kind of method and apparatus of sheet material forming
Technical field
The invention belongs to field of laser processing, refer in particular to a kind of sheet material and preheat softening and impact forming method and device, be specially adapted to the shaping of high duty metal sheet material through laser.
Background technology
The metal blank Plastic Forming has occupied crucial status as sheet material deep processing main method in whole national economy, be widely used in production industries such as Aero-Space, shipping industry, automobile panel, electronics, instrument.The method of plate Plastic Forming has: mould drawing, laser thermal stress are shaped and laser impact forming.Traditional mould drawing is that sheet metal is placed on the mould, under the forcing press effect, at the inner internal force that makes it to be out of shape that produces of sheet material, when the effect of internal force acquires a certain degree, just obtain the part of certain shape, though simple to operate, the production efficiency height, it is long to produce time, processing flexibility is poor, die cost is big, the high deficiency of manufacturing cost, and the mold cold drawing is only applicable to the good materials of plasticity such as mild steel, aluminium alloy and copper.
Laser thermal stress is shaped, also claim laser bending, it is to utilize being shaped of fuel factor that laser irradiation produces at material surface, during promptly with high energy laser beam scanning sheet metal, formed the uneven temperature field all very big to the room and time gradient in the zone of laser beam irradiation, unbalanced stress deforms sheet material on the sheet metal thickness direction thereby bring out.Have with short production cyclely, flexible big, can be shaped is difficult to the advantages such as fragile material that are shaped at normal temperatures, still in process, the thermal stress of inducing need surpass the yield limit of material, sheet material could be out of shape, so sheet material needs degree of depth heating, the surface quality of drip molding to be difficult to control.
Laser impact forming is the manufacturing process that the stress effect of utilizing the light laser of short pulse and matter interaction to produce shock wave makes plate generation plastic deformation, be that the high energy short pulse laser beam is passed transparent restraint layer and shone on the energy-absorbing layer that is coated in the metal blank surface, energy-absorbing layer gasifies after absorbing laser energy, vapor absorption laser energy after the gasification forms plasma, plasma continues to absorb energy and blasts, form shock wave, when shock wave peak pressure during greater than the dynamic yield limit of material, plate generation plastic deformation is repeatedly impacted the large tracts of land that can finish sheet material by multiple spot and is shaped.Its processing flexibility and processing is big, advantages such as processing panel surface quality is good, for example number of patent application is 01134063, " a kind of method and apparatus of laser-impact precision form ", but in the laser impact forming process, the sheet metal deformation amount is small, for high strength alloy steel, the sheet deformation amount is littler, even not distortion, and be accompanied by shock peening in the impact process, make the more difficult realization distortion of follow-up impact.
Summary of the invention
The objective of the invention is for a kind of method and apparatus of sheet material large area deformation is provided, overcome the of poor quality and little deficiency that waits of laser impact forming deflection of laser thermal stress profiled surface, it can directly form the sheet material material, when being impacted, sheet material has bigger deflection, high dimension precision, surface quality preferably, can be directly as the instrument of sheet forming.
The inventive method uses carbon dioxide laser as pre-heating plate, the temperature of infrared radiation thermometer observing and controlling sheet material heating, neodymium glass laser provides the light laser of the short pulse of inducing the shock wave generation for it, laser blast wave is as the plastic force source that makes sheet material, and has the measurement feedback device of sheet deformation amount.
The device of implementing this method comprises LASER HEATING system, laser-impact system, control system, workpiece clamp system, measurement feedback system.The LASER HEATING system comprises carbon dioxide laser, light pipe, completely reflecting mirror, hot spot adjusting device, in the hot spot adjusting device focus lamp is arranged; Light pipe couples together carbon dioxide laser, completely reflecting mirror and hot spot adjusting device successively, and the continuous laser that carbon dioxide laser is produced is delivered to the surface that workpiece need heat; The laser-impact system comprises neodymium glass laser, light pipe, completely reflecting mirror, hot spot adjusting device, in the hot spot adjusting device focus lamp is arranged, light pipe couples together neodymium glass laser, completely reflecting mirror, hot spot adjusting device, also can focus on the pulse laser transmission of neodymium glass laser generation the zone to be impacted, surface of workpiece; Focus lamp optical axis in LASER HEATING system and the laser-impact system is positioned at workpiece to be treated on the normal of shock surface, workpiece clamp system comprises workpiece, work piece holder, five-axle linkage workbench, covers the energy-absorbing layer of workpiece two side surfaces, clamping workpiece and places work piece holder on the workbench of five-axle linkage in work piece holder; Measurement feedback system comprises infrared measurement of temperature feedback device and displacement measurement feedback device, control system is made up of computer, central control processor, carbon dioxide laser controller, neodymium glass laser controller, wherein by computer input plate machining information, and the information of a processing and conversion passes to central control processor with control carbon dioxide laser generator, hot spot adjusting device, neodymium glass laser, infrared measurement of temperature feedback device, displacement measurement feedback device, five-axle linkage workbench, central control processor acceptance simultaneously and processing feedback information; Measurement feedback system comprises infrared measurement of temperature feedback device and displacement measurement feedback device, and infrared survey feedback device and displacement measurement feedback device are collected temperature information and displacement information respectively, and feed back to central control processor.
The invention process process is as follows:
(1) according to the size shape of processing work, unfolding calculation blank dimension, the laser cutting plate is to required blank shape, and the surface is scribbled the clamping workpiece of first energy-absorbing layer on anchor clamps;
(2) controller of carbon dioxide laser receives work order, and controlled carbon dioxide laser is started working, and the carbon dioxide laser irradiation that sends makes workpiece zone heating to be impacted on absorbed layer;
(3) heating region sends infrared ray and passes on the infrared measurement of temperature feedback device, and when arriving the temperature of appointment, the infrared measurement of temperature feedback device is given central control processor with feedback information, carbon dioxide laser is quit work, and neodymium glass laser is started working;
(4) on second energy-absorbing layer of laser pulse irradiation at surface of the work of the optimization that the neodymium laser laser instrument sends, vaporization behind second energy-absorbing layer absorption energy, ionization, formation plasma, plasma continues to absorb the energy blast of laser, produce the high-amplitude shock wave, make material generation Plastic Forming;
(5) the displacement measurement feedback device is accepted work order, measures the deflection of shock point, and gives central control processor feedback information; Five-axle linkage movable workbench subsequently heats in new zone again, impacts, measures again, impacts by carried out pointwise in an orderly manner by the five-axle linkage workbench, forms the shape and the corresponding information of plate preliminarily forming;
(6) impact the back feedack according to plate, laser controller is optimized the technological parameter in the follow-up laser-impact process, as laser energy, pulse width, spot size, heat time heating time and impact number of times,, realize accurate partial plastic forming of plate or monolithic molding to obtain different deflections.
The present invention is owing to adopt carbon dioxide laser that plate is carried out thermoplastic earlier, the yield limit of sheet material is declined to a great extent, and tool makes material have good plasticity, therefore under the identical situation of other parameter, deflection ratio during impact is big when not adding thermal shock, this will help reducing the number of times that impacts when being shaped, improved production efficiency, make the impact forging of high-intensity steel alloy easy simultaneously, make laser impact forming have very big practicality and versatility, also reduced simultaneously requirement, for the middle low power laser instrument is being opened up new field aspect the plate Plastic Forming to laser output power; Compare with the laser thermal stress shaping, heating in the laser impact forming is used for reaching softening metal material, making it yield strength reduces, but not be shaped like that to thermal stress, obtain the power of plastic deformation by degree of depth heating, therefore heating-up temperature is lower, structure property to sheet metal is less with the quality influence on surface, and the compression stress that forms in follow-up impact process will reduce harmful tension that sheet material produces owing to heating process greatly, even the surface of sheet material still keeps compressive stress state; Because laser blast wave is as sheet forming power source, thereby it is the contactless shaping of no mould, owing to adopt the workbench of five-axle linkage, can realize having realized the three-dimensional stereo forming of sheet material to a plurality of directions impacts of sheet material; Because laser spot size can focus to centimetre, millimeter magnitude even micron order, therefore both can carry out local fine quantitative Accurate Shaping, also can carry out large-area impact forging; Surface quality before the sheet material forming is required to be lower than conventional Sheet Metal Forming Technology, and the fineness of profiled surface is increased, so the laser impact forming of preheating sheet material have usage range efficient height, drip molding wide, that be shaped and have the good superior characteristics of serviceability.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples.
Fig. 1 preheats device schematic diagram with impact forging according to the laser that the inventive method proposes.
1. feedback device 13. continuous lasers 14. the 3rd total reflection mirror 15. second light pipes 16. carbon dioxide lasers 17. carbon dioxide laser controllers 18. the 4th total reflection mirror 19. second light spot adjusting devices 20. infrared measurement of temperature feedback devices 21. first energy-absorbing layers 22. computers 23. second energy-absorbing layers are measured in 12. displacements of central control processor 2. five-axle linkage workbench 3. first light spot adjusting devices 4. first total reflection mirrors 5. neodymium glass laser controllers 6. neodymium glass laser instruments 7. first light pipes 8. second total reflection mirrors 9. pulse lasers 10. work piece holders 11. workpiece
The specific embodiment
Describe the details and the working condition of the concrete device of the present invention's proposition in detail below in conjunction with Fig. 1.
This device comprises LASER HEATING system, laser-impact system, control system, workpiece clamp system, measurement feedback system.The LASER HEATING system comprises carbon dioxide laser (16), second light pipe (15), the 3rd completely reflecting mirror (14), the 4th completely reflecting mirror (18), the second hot spot adjusting device (19); The laser-impact system comprises neodymium glass laser (6), first light pipe (7), first completely reflecting mirror (4), second completely reflecting mirror (8), hot spot adjusting device (2); Workpiece clamp system comprises workpiece (11), covers first energy-absorbing layer (21) of surface of the work, second energy-absorbing layer (23), work piece holder (10), five-axle linkage workbench (2); Control system is made up of computer (22), central control processor (1), carbon dioxide laser controller (17), neodymium glass laser controller (5); Measurement feedback system comprises infrared measurement of temperature feedback device (20) and displacement measurement feedback device (12).
Become procedure to be input in the computer (22) message composition of processing, send control information and central control processor (1) is passed in work order in succession by computer (22), pass to carbon dioxide laser (16) through carbon dioxide laser controller (17), after carbon dioxide laser (16) receives work order, send continuous power density 10
3~10
4W/cm
2The laser of magnitude (13), and through second light pipe (15), the 3rd completely reflecting mirror (14), the 4th completely reflecting mirror (18) and the second hot spot adjusting device (19), irradiation makes sheet material (11) heating on sheet material (11) surface energy absorbed layer (21), the energy of continuous laser (13) is regulated by laser controller (16).After sheet material (11) is heated laser (13) heating, temperature rises and the continuous infrared ray that outwards sends corresponding wavelength stabilization, thermometric feedback device (20) is measured the temperature of sheet material according to the infrared wavelength of collecting, and give central control processor (1) feedback information, when the temperature of sheet material reaches the temperature of setting, central control processor (1) sends instruction, carbon dioxide laser (16) is quit work, neodymium glass laser (6) is started working, laser instrument (6) sends pulse energy 40-160J, pulse width 50-120ns, power density is 10
8W/cm
2Above pulse laser beam (9), the facular model of laser beam (9) can be various modes such as basic mode, multimode, it is regulated and control by neodymium glass laser controller (5).Laser beam after being optimized by neodymium glass laser (6) is through first light pipe (7), first completely reflecting mirror (4), second completely reflecting mirror (8), first hot spot adjusting device (3) irradiation is to second energy-absorbing layer (23) on workpiece (11) surface, after second energy-absorbing layer (23) absorbs high energy pulse laser (9), vaporization rapidly, ionization forms plasma, plasma continues to absorb laser energy, form detonation wave, generation is to the high-amplitude shock wave of metal blank workpiece (11) internal communication, when its surge pressure is higher than the dynamic yield strength of metal blank, metal blank produces plastic deformation.Neodymium glass laser (6) is accepted to instruct and is quit work subsequently, displacement measurement feedback device (12) is started working, displacement measurement (12) feedback device is measured deflection, and feed back to central control processor (1), energy when heating to optimize the preceding continuous laser (13) of impact next time, the parameters such as time of area heated and heating, and parameters such as pulse laser (9) when work energy, spot size.Central control processor (1) sends instruction subsequently, make moving of five-axle linkage workbench (2), be fixed on that work piece holder (10) on the five-axle linkage workbench (2) is gone up and workpiece (11) in company with moving, because five-axle linkage workbench (10) can be done along three axial moving and rotating around two axles, thereby realize the three-dimensional stereo forming of sheet material (11), after workbench (10) moves, finished heating-impact-measurement-mobile working cycles, central control processor (1) sends instruction again and finishes heating-impact-measurement-mobile working cycles, till the shape and size of impacting meet the requirements, thereby realize the Accurate Shaping of whole sheet material.