CN100391682C - Hole-forming method and device based on laser shock wave technology - Google Patents

Abstract

The present invention relates to a hole forming method based on a laser impact wave technique. The present invention is characterized in that the position needing to be drilled of a work piece is sequentially coated with an energy absorption coating layer and a covering transparent restraint layer, and the area of the energy absorption coating layer and the covering transparent restraint layer is slightly larger than the area of the hole to be processed; according to the shape and size of the hole to be processed, a concave die is manufactured; the work piece is arranged on the concave die, the centers of the energy absorption coating layer, the transparent restraint layer, the hole to be processed and the concave die are superposed, and the concave die is arranged on a multi-shaft linkage working table; according to the size and shape of the hole to be formed, the size of laser spots and the energy of laser pulses are determined; laser beams emitted by a laser pass through a laser conducting pipe, a full reflection lens, a laser spot regulating device and a converging device, penetrate through the transparent restraint layer and act on the energy absorption coating layer to induce the generation of laser impact waves; the laser impact waves apply pressure to the work piece, and thus, the work piece is punched. The present invention has the advantage of large range of processing hole diameters, low processing cost, etc.; the present invention can be used for punching both micro holes and large holes.

Description

A kind of manufacturing process of the hole based on laser shock wave technology

Technical field

The present invention relates generally to field of laser processing, refer in particular to a kind of quick forming method and device of the hole based on laser shock wave technology, be specially adapted to the circular hole, square hole, leg-of-mutton hole and the irregular irregularly-shaped hole that on the sheet metal of thickness, are shaped less than 2.5mm.

Background technology

Sheet metal processing has occupied crucial status in whole national economy, be widely used in production industries such as Aero-Space, shipping industry, automobile panel, household electrical appliances, because the needs of structure, many circular holes and hole in irregular shape are usually arranged on the sheet metal, and its common processing method mainly contains drilling, die punching and laser boring and the laser cutting hole is shaped.

Boring is the present widely used manufacturing process of cut deal, but because the rigidity of thin plate is extremely low, plasticity is big, and easy deformation is under the effect of drill thrust, be easy to generate torsional deformation, the hole shape of getting is irregular, as flat hole, polygonal hole, and place, aperture overlap, burr, even drill-pipe-sticking-head or the drill bit phenomenon that fractures appears, especially the shaping for the hole on the thick ultra-thin sheet material of 0.1～1.5mm does not have desirable drilling method so far.

Die punching is a processing the most frequently used method in irregular hole on the thin plate, during punching, and the reasonable clearance of, die protruding in order to guarantee, need the higher molding grade of tolerance, mould is made difficulty, processing cost height, and installation, gap adjustment trouble and inaccuracy protruding, die; Usually want deburring behind the blanking.Casing, the cabinet made for large-scale sheet metal component all can run into hole vertically a large amount of or that tilt when assembling, then mould often can't be processed.

Laser boring is the manufacturing process in another kind of hole, it is suitable for the shaping of micro hole, it mainly utilizes fuel factor to make that material dissolves, gasification materials forms the hole, its intrinsic shortcoming be because the strong volatile matter that high temperature produces meet can be around the hole after cold and inwall formed a large amount of irregular heaps and spattered thing and re cast layer, and the hole has certain tapering, and all these has influenced the quality in hole greatly.

When the aperture is big, usually adopt the laser cutting way to come shaped hole, the raw material that the joint-cutting that promptly utilizes the feed motion device that aperture is formed by connecting removes on the blank form.The most frequently used cutting tool is CO ₂Laser instrument, though advantage such as it has the efficient height, and is easy to operate, have the following disadvantages: rhythmic ripple on the otch section has had a strong impact on the vent surface quality; Because fuel factor, plate surface usually has micro-crack, and the dross phenomenon appears in the otch below; Because the complementary gas that adopts, the material of fusing splashes, and the environment of production is relatively poor, can't satisfy the processing of high cleanliness part; The scope of materials processing is subjected to certain restriction, some materials such as materials processings such as copper, aluminium alloy is become difficult, even might damage the external optical element of laser system.

The technology the most approaching with the technology of the present invention is the explosive charge punching, explosive forming mainly is the moment high temperature that produces when utilizing explosive charge, high-pressure shocking wave punching, but the technological parameter of blast punching is difficult to control, shock wave reaches several milliseconds action time, diffusion effect is big, shape that can not the Accurate Shaping hole, and security is relatively poor, so be not used.

Summary of the invention

The objective of the invention is for provide overcome above in the deficiency aspect crudy and the processing safety, be provided for shaping quick and easy method in hole on the thin plate, it can directly be shaped to the hole, and can obtain higher size, form accuracy and surface roughness, its circular hole that not only can be shaped, the erose hole that can also be shaped can be directly as the plate hole forming tool.

A kind of manufacturing process of the hole based on laser shock wave technology, it is characterized in that: on the position that needs shaped hole on the workpiece, scribble energy-absorbing coating successively, cover transparent restraint layer, both areas are bigger slightly than machining hole, again according to the shape and size size in hole to be processed, make the die corresponding, that cutting edge is sharp, the workpiece that upper surface is posted energy-absorbing coating, transparent restraint layer places on the die, and four centers of hole to be processed on energy-absorbing coating, transparent restraint layer, the workpiece and die are overlapped, die is placed on the multi-shaft interlocked workbench again; According to the size and the shape in the hole of required shaping, determine spot size, according to following formula, determine the energy of laser pulse:

$\left\{\begin{array}{c}P={10}^{-9}{\left(\frac{\mathrm{\&alpha;}}{2\mathrm{\&alpha;}+3}\right)}^{\frac{1}{2}}\&CenterDot;Z^{\frac{1}{2}}\&CenterDot;{\left(\frac{4\mathrm{\&beta;E}}{\mathrm{\&pi;\&tau;}{d}^2}\right)}^{\frac{1}{2}}\\ \frac{2}{Z}=\frac{1}{Z_1}+\frac{1}{{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="C20061003950500081.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2}\end{array}\right.$ With $\frac{P}{\mathrm{\&pi;dh}}\&GreaterEqual;{\mathrm{\&tau;}}^{\mathrm{dyn}}$

Wherein, P (t) is the pressure of shock wave; D is the diameter of circular hole; α is the constant relevant with laser pulse and wavelength; The impedance of Z shock wave; Z ₁Be the workpiece impedance; Z ₂Impedance for the constraint medium; E is the energy of laser pulse; β is an absorption coefficient; τ is the wavelength of laser pulse; H is the thickness of workpiece; τ ^DynDynamic Fracture intensity for workpiece; Laser instrument gives off laser beam by light pipe, total reflective mirror, hot spot adjusting device, convergence apparatus, sees through transparent restraint layer and acts on the energy-absorbing coating, induces laser blast wave to produce, and laser blast wave is exerted pressure to workpiece, finishes the workpiece punching.

Restraint layer can be optical glass or water; Energy-absorbing coating can be selected the pitch-dark of market purchase for use.

The manufacturing process in above-mentioned a kind of hole based on laser shock wave technology, energy-absorbing coating, transparent restraint layer can select for use the flexible lamina described in the patent ZL02138338.3 to substitute;

Enforcement the inventive system comprises laser generator, light-conducting system, workpiece clamp system, control system; Light-conducting system comprises light pipe, total reflective mirror, hot spot adjusting device, convergence apparatus; Workpiece clamp system comprises energy-absorbing coating, transparent restraint layer, workpiece, die, multi-shaft interlocked workbench; Control system is made up of computer, machine tool controller, laser controller.

The hot spot adjusting device is meant the spring that can freely stretch, and can regulate the relative position of convergence apparatus and workpiece; Focusing arrangement is meant convex lens.

Light pipe is the most basic path of laser beam transmission, and the one end is connecting laser generator, and the other end faces workpiece clamp system, successively total reflection border, hot spot adjusting device and focusing arrangement is coupled together; Workpiece system is transparent restraint layer, energy-absorbing coating, workpiece, die from top to bottom successively, is multi-shaft interlocked workbench at last; Computer is the center of control system, controlling machine tool controller by the instruction that it sends, and unite machine tool controller and controlling laser controller together, laser controller is being controlled laser generator, and machine tool controller is being controlled hot spot adjusting device and multi-shaft interlocked workbench.

Laser beam sees through transparent restraint layer, act on the opaque energy-absorbing layer of laser, energy-absorbing layer gasifies after absorbing superlaser immediately, ionization, the blast of formation plasma, form laser blast wave, because the effect of contraction of restraint layer, the pressure of shock wave raises rapidly, its surge pressure reaches several GPa, be far longer than the Dynamic Fracture limit of workpiece material, finish, so just apply a sudden applied load at plate surface because the pressure of shock wave was created in tens extremely short nanosecond, make plate and die that strong effect take place, the cutting edge that die is sharp is sheared the material in the zone of action from parent, because it is finished under the Under High Strain rate, formed the Adiabatic Shear band in the sheet material upper cavity die cutting edge zone of action, make fracture smooth, thereby it is accurate to form size on sheet material, the hole that inner surface is smooth.

The processing method of this invention has following advantage:

(1) because the pressure height of laser blast wave, the time of effect short (ns level), the hole can once-forming, rapidly and efficiently; The clean environment of processing has been avoided using laser cutting technique to produce extremely fine particle and dust, satisfies the requirement of processing than the high cleanliness product better.

(2) the material processed scope is wide, and processing flexibility and processing is big.The metal material of all can not only be processed, hard crisp nonmetallic materials can also be processed, as pottery; Owing to adopt multi-shaft interlocked workbench, not only removable can also forwarding to, therefore the hole of processing is not limited by the position, and the hole on not only can the process water plane also can be in the hole on the processing inclined-plane; Do not need to have matching problem protruding, that die is made like that yet, do not have the adjustment in gap in the use yet to diel, very convenient.

(3) do not use cutter, do not need external force, belong to contactless processing, therefore do not exist cutter reconditioning, wear and tear and fracture, processing cost is reduced; Form because the shaping in hole is an Adiabatic Shear, the heat-affected zone of material is little, and hole surface is smooth, smooth, need not deburring again.

(4) the processing pore diameter range is big, not only can beat micro hole, can also beat macropore, has overcome the limitation that ultra-short pulse laser and PRK can only be beaten micro hole.And aperture size is accurate, and there is not tapering in good stability.

(5) when the hole is shaped, the aperture material around has also been carried out shock peening,, suppressed the generation of fatigue crack in the part use, prolonged the tired service life of part at the material surface compressive residual stress that has been shaped.

(6) it both can once-forming sheet material on single macropore, but also once-forming within the scope that effectively hot spot covers, a plurality of apertures of concentrating relatively of position, the hole that disperses for the position can be moved the hole that multi-shaft interlocked workbench finishes on the workpiece one by one by numerical control program control and is shaped.

Description of drawings

Be described further below in conjunction with accompanying drawing and example

Fig. 1 is the quick device schematic diagram that is shaped in the hole based on laser shock wave technology that proposes according to the present invention.

Fig. 2 is that pulse laser is the assay maps of going out single hole on the LD31 thin plate of 0.4mm at thickness.

Fig. 3 is that pulse laser is the assay maps of once going out a plurality of apertures on the LD31 thin plate of 0.25mm at thickness.

1 laser generator, 2 laser beams, 3 leaded light walls, 4 total reflection borders, 5 hot spot adjusting devices, 6 focusing arrangements, 7 flexible laminas, 8 workpiece, 9 dies, 10 multi-shaft interlocked workbench 11 machine tool controllers 12 computers 13 laser controllers

The specific embodiment

Laser generator (1) produce power is the laser pulse bundle (2) of 8～80 nanoseconds in 10～100 Jiao Er, duration, and power density is greater than GW/cm ²Through facular model can be various modes such as basic mode, multimode, through leaded light wall (3), total reflection border (4), pass to spot size adjusting device (5), regulate on the focusing arrangement (6), hot spot adjusting device (5) can be regulated the distance between focusing arrangement and the sheet material, obtain required spot diameter, laser irradiation subsequently is on the transparent restraint layer of the energy transformant of plate surface, energy-absorbing coating, and the expansion of restraint layer confining plasma improves the pressure of plasma stock wave.After energy-absorbing coating absorbs superlaser, vaporization rapidly, ionization form plasma, plasma continues to absorb laser energy, form detonation wave, act on sheet metal (8), under the acting in conjunction of the pressure of detonation wave and die (9), material (8) is thrown off from parent in the zone in die (9) aperture, be the hole of required shaping, because multi-shaft interlocked workbench (10) has moving and two rotations of three coordinates, can realize five-axle linkage, be shaped thereby can carry out the hole to optional position on the workpiece easily.

As shown in Figure 2, laser generator (1) produce power is the laser of 17.6J, the pulse shape gaussian model that is as the criterion, pulsewidth 23ns, having formed diameter under the common influence through hot spot adjusting device (5) and focusing arrangement (6) is the 8mm hot spot, restraint layer is an optical glass, energy-absorbing coating is that the 86-1 type is pitch-dark, after having absorbed superlaser (2), vaporization rapidly, ionization forms plasma, plasma continues to absorb laser energy, forming detonation wave acts on the LD31 aluminum alloy plate materials (8) that thickness is 0.4mm consumingly, when its surge pressure surpasses the Dynamic Fracture limit of sheet material (8) and die (9) acting in conjunction that diameter is φ 6mm, be the hole of φ 6mm at LD31 aluminum alloy plate materials shaping form diameter.

As shown in Figure 3, before laser irradiation, make the die (9) in the hole that relevant position and size are arranged, the workpiece (9) that posts flexible lamina (7) is placed on the die (8).Laser generator (1) produce power is 42J, laser, the pulse shape gaussian model that is as the criterion, pulsewidth 23ns, having formed diameter under the common influence through hot spot adjusting device (5) and focusing arrangement (6) on flexible lamina (7) surface is the 16mm hot spot, after flexible lamina (7) absorbs superlaser (2), vaporization rapidly, ionization forms plasma, plasma continues to absorb laser energy, be formed on active force huge impact ripple on LD31 aluminum alloy plate materials (8) surface, and die (9) acting in conjunction, be the last a plurality of apertures that are shaped of LD31 aluminum alloy plate materials (8) of 0.25mm at thickness.

Claims (3)

1. manufacturing process based on the hole of laser shock wave technology, it is characterized in that: on the position that needs shaped hole on the workpiece, scribble energy-absorbing coating successively, cover transparent restraint layer, both areas are bigger slightly than machining hole, again according to the shape and size size in hole to be processed, make corresponding, the die that cutting edge is sharp (9), upper surface is posted energy-absorbing coating, the workpiece of transparent restraint layer (8) places (9) on the die, and make flexible lamina (7), the three center that workpiece (8) is gone up hole to be processed and die (9) overlaps, and die (9) is placed on the multi-shaft interlocked workbench (10) again; According to the size and the shape in the hole of required shaping, determine spot size, according to following formula, determine the energy of laser pulse:

$\left\{\begin{array}{c}P={10}^{-9}{\left(\frac{\mathrm{\&alpha;}}{2\mathrm{\&alpha;}+3}\right)}^{\frac{1}{2}}\&CenterDot;Z^{\frac{1}{2}}\&CenterDot;{\left(\frac{4\mathrm{\&beta;E}}{\mathrm{\&pi;\&tau;}{d}^2}\right)}^{\frac{1}{2}}\\ \frac{2}{Z}=\frac{1}{Z_1}-\frac{1}{Z_2}\end{array}\right.$ With $\frac{P}{\mathrm{\&pi;dh}}\&GreaterEqual;{\mathrm{\&tau;}}^{\mathrm{dyn}}$

Wherein, P (t) is the pressure of shock wave; D is the diameter of circular hole; α is the constant relevant with laser pulse and wavelength; The impedance of Z shock wave; Z ₁Be the workpiece impedance; Z ₂Impedance for the constraint medium; E is the energy of laser pulse; β is an absorption coefficient; τ is the wavelength of laser pulse; H is the thickness of workpiece; τ ^DynDynamic Fracture intensity for workpiece; Laser generator (1) gives off laser beam (2) by light pipe (3), total reflective mirror (4), hot spot adjusting device (5), focusing arrangement (6), seeing through transparent restraint layer acts on the energy-absorbing coating, induce laser blast wave to produce, laser blast wave is exerted pressure to workpiece (8), finishes workpiece (8) punching.

2. the manufacturing process in a kind of hole based on laser shock wave technology according to claim 1, it is characterized in that: restraint layer can be optical glass or water; Energy-absorbing coating can be selected the pitch-dark of market purchase for use.

3. the manufacturing process in a kind of hole based on laser shock wave technology according to claim 2, it is characterized in that: energy-absorbing coating, transparent restraint layer can select for use flexible lamina to substitute; Flexible lamina is mixed according to a certain ratio by two groups of silicon gels of different component and additive and the transparent restraint layer and the energy-absorbing layer that form are formed, transparent restraint layer adopts the GN-521 silicon gel, formulated component is: the M45 of silicon gel～55%, silicon gel N50～35%, additive P5～10%; The 86-1 type that energy-absorbing layer adopts the splash method to be coated on the transparent restraint layer is pitch-dark; Transparent restraint layer thickness is 0.6mm～1.6mm, and the energy absorption layer thickness is 80 μ m～160 μ m.

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