CN101559539B

CN101559539B - Sheet metal laser high-precision hot-bending forming

Info

Publication number: CN101559539B
Application number: CN 200910015653
Authority: CN
Inventors: 石永军; 刘衍聪; 伊鹏
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2009-05-19
Filing date: 2009-05-19
Publication date: 2011-12-21
Anticipated expiration: 2029-05-19
Also published as: CN101559539A

Abstract

The invention is a method for improving sheet metal laser hot-bending forming precision. A forming workpiece is fixed on a three-dimensional numerical control platform, continuous laser beams heat thesurface of sheet metal along given motion track at a certain scanning speed, different pressures are applied at the distance of about 1 to3 facula diameters behind the laser beams, smaller pressure i s applied at the position of greater bending angle, greater pressure is applied at the position of smaller bending angle, so as to reduce the change of bending angle along the heated sheet formed sheet and improving the forming precision of the forming workpiece. The method is applied to high-rigidness and fragility difficultly-deformed sheet high-precision forming, and has broader application prospect in the fields of aerospace, medicine and microelectronics.

Description

Sheet metal laser high-precision hot-bending forming

Technical field

The present invention relates to a kind of method of utilizing laser beam to realize sheet metal high accuracy bending forming, belong to machinery manufacturing technology field, the sheet metal that can be applicable to small lot or difficult moulding material does not have the mould quick shaping machining.

Technical background

The LASER HEAT forming technique is as a kind of new sheet material forming process, laser technology is incorporated in the plastic forming technology, utilizes high energy laser beam local heat material surface, bring out inhomogeneous thermal stress, make the material production plastic deformation, thereby obtain required target shape.Compare with cold forming process such as conventional panels drawing, need not mould and external force in the LASER HEAT forming process, thereby flexible big, with short production cycle, be particularly suitable for the processing of the parts of many kinds, small lot; Be shaped owing to belong to hot accumulation, this technology especially is fit to the shaping of difficult moulding materials such as high rigidity, high fragility, as titanium alloy, nickel alloy, pottery and silicon chip etc.; The laser energy density height, the heat affected area is little, and is little to the drip molding effect of material performance, and is difficult for producing rugosity in the forming process.Therefore, the LASER HEAT forming technique has great application prospect in fields such as Aero-Space, automobile, boats and ships and microelectronics, and preliminary commercial Application also demonstrates the huge potentiality to be exploited of this technology.

At present, because diverse location cold conditions material is different from the quasi-steady state temperature to restraining force variation, heating initiating terminal temperature and the clearing end temperature of heating region, cause LASER HEAT be shaped workpiece in the processing except produce expectation along the distortion of heater wire normal direction transverse curvature, also can produce and not wish the distortion that obtains in the forming processes such as flexural deformation along heater wire, buckling deformation, cause along heater wire sheet bending angle difference, big a little in the both sides of plate angle of bend, and less at the middle bent angle of plate.Although in conventional hot forming, can not consider, but the workpiece of having relatively high expectations for forming accuracy, the parts in fields such as picture Aero-Space, medical treatment and microelectronics, these shaping errors not only can influence the assembly precision of workpiece, also have a strong impact on the service life of workpiece, and restricted the LASER HEAT forming technique and use in above-mentioned field.In the LASER HEAT forming process, because the non-expectation distortion of sheet material is accompanied by the expectation distortion and produces simultaneously, therefore, must grasp LASER HEAT be shaped in both and deposit the effective workaround of contradictory phenomena, could be under the prerequisite that guarantees the expectation distortion, reduce along heater wire sheet bending angle, improve the forming accuracy of workpiece.

Summary of the invention

In order to overcome in the metal board laser hot forming along the different problem of heater wire sheet bending angle, the invention provides a kind of metal board laser thermo shaping method of heating power combination, reduce along the variation of heater wire sheet bending angle, improve the forming accuracy of sheet metal.

Task of the present invention solves the technical scheme that its technical problem adopts: sheet metal places on the three-dimension numerical controlled platform, and an end is fixed.In order to prevent the grease influence heat transfer of sheet metal surface, sheet metal cleans with acetone.Because mild steel is very low to its absorptivity, in order to improve the absorption coefficient of laser, evenly is coated with the last layer coating in the metal surface, carries out melanism and handle.Continuous laser beam, cools off heating region by natural cooling, forced convertion air cooling or forced convertion water-cooled along given movement locus heating metal plate material surface with certain sweep speed.The main cause that generation changes along heater wire sheet bending angle, the one, in the cold conditions material of diverse location sheet metal restraining force difference to heating region, restraining force is smaller in the both sides of plate, and bigger in the middle part of sheet material restraining force, the restraining force difference causes the plastic shrinkage distortion of high-temperature area different; The 2nd, lower than quasi-steady state temperature in the heating process in heating initiating terminal temperature, and in the clearing end temperature than quasi-steady state temperature height.In order to obtain along the identical angle of bend of heater wire, the distance of about 1～3 spot diameter applies different pressure behind laser beam, this place's sheet material changes the forward bending into by back-flexing, the top surface temperature reduces and underlaying surface temperature still will continue to raise a period of time, the lower surface thermal expansion amount continues to increase, and temperature still very high (about about 450 ℃), the sheet metal yield strength descends greatly and easily deformable under this temperature conditions, and therefore sheet material can obtain bigger plastic deformation under less pressure.Carry out pressure for thicker sheet metal with mechanical mode and apply, for thin sheet metal, available high pressure draught carries out pressure and applies.Apply bigger pressure corresponding to the bigger increase of angle of bend, apply less pressure corresponding to the less increase of angle of bend, concrete force value is with technological parameter and sheet material geometrical variations.In order to obtain the needed working process parameter of each scanning, build-up pressure size, spot diameter, laser power and sweep speed and sheet deformation fundamental relation database.According to database and the requirement of sheet deformation amount, can instead obtain needed working process parameter.

Compare with the sheet metal hot forming of routine, result of the test shows that this method can obtain uniform sheet bending angle along the heater wire direction, improves the forming accuracy of sheet metal greatly.Owing at high temperature carry out sheet material forming, this method not only is suitable for the common metal material, and can be applicable to the shaping of high hard crisp difficult-to-deformation material, in fields such as Aero-Space, medical machinery and microelectronics bigger application prospect is arranged.

Description of drawings

Fig. 1 high-precision laser hot-bending forming device schematic diagram

Fig. 2 high-precision laser hot-bending forming process schematic diagram

1 control system, 2 laser instruments, 3 speculums, 4 focus lamps, 5 laser beams, 6 Forming Workpiece, 7 three-dimension numerical controlled, 8 anchor clamps, 9 pressure output systems

The specific embodiment

Below in conjunction with accompanying drawing the specific embodiment of the present invention is illustrated.High-precision laser hot-bending forming device is by control system (1), CO ₂Laser instrument (2), speculum (3), focus lamp (4), pressure output system (9), anchor clamps (8), three-dimension numerical controlled (7) and Forming Workpiece (6) are formed, as shown in Figure 1.

The concrete forming step of sheet metal is as follows:

1, with acetone the sheet metal surface is cleaned;

2, evenly be coated with last layer laser absorbent coating on the sheet metal surface, carry out melanism and handle;

3, Forming Workpiece (6) places on three-dimension numerical controlled (7), uses a fixedly end of Forming Workpiece (6) of anchor clamps (8), and laser beam (5) and pressure applying means (9) fixed-site are constant;

4, laser beam is sent by laser instrument (2), forms the light beam radiation of certain spot diameter on Forming Workpiece (6) surface by speculum (3) and focus lamp (4);

5, keep spot diameter constant, set up,, can instead obtain needed sweep speed and laser power according to fundamental relation database and sheet bending deformation requirements along heater wire sheet material maximum deflection angle and technological parameter fundamental relation database;

6, build-up pressure size, sheet material physical dimension, technological parameter and sheet bending distortion fundamental relation database, apply less pressure in the bigger position of angle of bend, apply bigger pressure in the less position of angle of bend, according to the variation at fundamental relation database and sheet bending angle, can determine in the needed force value in different heating position;

7, three-dimension numerical controlled (7) drive Forming Workpiece (6) move, make continuous laser beam (5) heat Forming Workpiece (6) surface along given movement locus b with certain sweep speed v, in laser beam (5) back apart from the F that exerts pressure of d place, laser beam center, pressure is applied according to the different heating position by pressure output system (9), as shown in Figure 2, carrying out pressure for thicker sheet material with mechanical mode applies, d is about the distance of 1～3 spot diameter, can carry out pressure with high pressure draught for thin sheet material and apply;

8, after heating was finished, sheet metal cooled off heating region by natural cooling, forced convertion air cooling or forced convertion water-cooled.

Claims

1. method that improves sheet metal laser hot-bending forming precision, the sheet metal laser high-precision hot-bending forming device is by control system (1), CO ₂Laser instrument (2), speculum (3), focus lamp (4), pressure output system (9), anchor clamps (8), three-dimension numerical controlled (7) and Forming Workpiece (6) are formed, Forming Workpiece (6) places on three-dimension numerical controlled (7), one end is fixed, continuous laser beam (5) with certain sweep speed along given movement locus heating metal plate material surface, it is characterized in that applying different pressure along the distance of heater wire 1～3 spot diameter behind laser beam, apply less pressure in the bigger position of angle of bend, apply bigger pressure in the less position of angle of bend, reduce along the variation of heater wire sheet bending angle, improve the forming accuracy of sheet metal, concrete implementation step is as follows:

(1), with acetone the sheet metal surface is cleaned;

(2), evenly be coated with last layer laser absorbent coating, carrying out melanism handles on the sheet metal surface;

(3), Forming Workpiece (6) places on three-dimension numerical controlled (7), with the fixing end of Forming Workpiece (6) of anchor clamps (8), laser beam (5) and pressure output system (9) fixed-site are constant;

(4), laser beam sends by laser instrument (2), forms the light beam radiation of certain spot diameter on Forming Workpiece (6) surface by speculum (3) and focus lamp (4);

(5), keep spot diameter constant, set up along heater wire sheet material maximum deflection angle and technological parameter fundamental relation database, according to fundamental relation database and sheet bending deformation requirements, anti-needed sweep speed and the laser power obtained;

(6), build-up pressure size, sheet material physical dimension, technological parameter and sheet bending distortion fundamental relation database, apply less pressure in the bigger position of angle of bend, apply bigger pressure in the less position of angle of bend, according to the variation at fundamental relation database and sheet bending angle, determine in the needed force value in different heating position;

(7), three-dimension numerical controlled (7) drive Forming Workpiece (6) move, make continuous laser beam (5) heat Forming Workpiece (6) surface along given movement locus b with certain sweep speed v, in laser beam (5) back apart from the F that exerts pressure of d place, laser beam center, pressure is applied according to the different heating position by pressure output system (9), carrying out pressure for thicker sheet material with mechanical mode applies, d is the distance of 1～3 spot diameter, carries out pressure for thin sheet material with high pressure draught and applies;

(8), the heating finish after, sheet metal cools off heating region by natural cooling, forced convertion air cooling or forced convertion water-cooled.