CN100581707C - Supersonic speed nozzle for laser cutting - Google Patents

Abstract

Disclosed is a supersonic speed nozzle used in laser cutting in the technical field of mechanical laser processing, comprising parallel sections, a contraction section, a laryngeal, and a divergent section, all of which are communicated as a whole. The laryngeal is a transitional cross section arranged between the contraction section and the divergent section. The divergent section comprises a first section and a second section, which assure the boundary layers on the wall of the supersonic speed area not disconnected. The first section and the second section are smoothly connected; the first section is arranged between the laryngeal and the second section; the first section is determined by a Blunt-Meier expansion line in the isentropic condition; the second section adopts an arc of large diameter to make the gradient of a curve reduced to 0 according to a simplified Hall designing method. When the invention is used to cut the laser, the cutting effect is good with fast speed and good cutting quality, and the cut lower edge does not have slag hanging. Particularly, when processing metal that is difficult to be processed, the invention can effectively blow away melt metal and other slag of high viscosity, and thus improves the cut quality and efficiency.

Description

The superonic flow nozzzle that is used for laser cutting

Technical field

What the present invention relates to is a kind of nozzle of field of mechanical technique, specifically is a kind of superonic flow nozzzle that is used for laser cutting.

Background technology

In laser cutting process, nozzle is a vitals of realizing laser cutting mainly as the passing away of laser beam and assist gas.Laser cutting process is high energy laser beam and assist gas results of interaction, and high-energy light beam guiding makes rapidoprint fusing even gasification on the one hand, and assist gas discharges motlten metal and part heat from otch on the other hand.Therefore reasonably nozzle arrangements can not only improve working ability, and the heat affected area is limited in the very little scope, has guaranteed the well processed quality.

The laser superonic flow nozzzle has two kinds of project organizations at present: a kind of is Lavalle type straight way structure, another kind is He Er (Hall) and Fu Ershi (foelsch) match Prandtl-Meyer expansion collimation method, but these two kinds of structures all are the method for designing development by the rocket assist chamber, the laser cutting jet size is than little many in rocket assist chamber, therefore the approximating method of these luminance curves is in small size processing, the difficulty that not only is shaped is big, and machining accuracy is low.

Through the literature search of prior art is found, Chinese patent application number is CN200510095474.X " a kind of laser cutting head ".This design considerations Lavalle architectural characteristic adopts Fu Er intellectual line approximating method, has higher designing requirement.But the design of above-mentioned superonic flow nozzzle, because the divergent section inwall as nozzle supersonic speed zone is the combination of straight line and luminance curve, so not only increased difficulty of processing, and the very difficult stationarity that guarantees supersonic flow, especially being connected of throat and divergent section is straightway, can not guarantee the continuity in wall boundary layer, can not guarantee that also supersonic flow is evenly distributed in pipe, popular parallel.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art and defective, a kind of superonic flow nozzzle that is used for laser cutting is provided, wherein divergent section replaces existing complex curve with large diameter circular arc, such design not only can greatly reduce difficulty of processing, and can guarantee machining accuracy, improve cutting efficiency.

The present invention is achieved by the following technical solutions, the present invention includes: parallel-segment, converging portion, throat, divergent section, this four part is an integral body that communicates, wherein the parallel-segment import is connected the storage gases at high pressure with the external laser air cavity, the parallel-segment outlet connects the import of converging portion, the converging portion outlet connects throat, and throat's opposite side is a divergent section, and throat is the transition section of being located between converging portion and the divergent section.Gases at high pressure from the parallel-segment outflow, the converging portion of flowing through accelerates to transonic flow, and stream is finished transonic speed transition to supersonic flow through throat again, at last in divergent section, supersonic flow continues expansion and reaches predetermined Mach number, and the guiding supersonic airstream stable and uniform that becomes.

The outside between described parallel-segment and the converging portion is provided with fixing and hermetically-sealed construction, and the sealing that is used for the gases at high pressure flow field is with fixing.

Described parallel-segment entrance point is provided with linkage section, and linkage section is whole nozzle and laser instrument air cavity coupling part, and employing is threaded.

Described converging portion, it is shaped as the Wei Duoxinjisi curve-like, the throat's velocity of sound isopleth vertical axis that guarantees to flow through, and can eliminate as far as possible in accelerator and reflux makes air-flow quicken to reach velocity of sound, keep again simultaneously flowing evenly with to go out streamline parallel.

Described parallel-segment, its diameter D ₀Depend on throat diameter D _c, $D_0=D_c{\left[\frac{1}{M_0}{\left(\frac{1+0.2M_0^2}{1.2}\right)}^{\frac{k+1}{2(k-1)}}\right]}^{1/2},$ M ₀For converging portion inlet Mach number, generally select M ₀=0.02～0.1, k is an adiabatic coefficent, and diatomic gas is k=1.4, and polyatomic gas is k=5/3, the parallel-segment length L ₀Be that the longer the better in theory, but the influence of Stimulated Light focal length usually, general L ₀Length is got 10 times of throat diameter D _c

Described throat minimum diameter is by design pressure and the decision of environmental pressure level pressure ratio, throat section diameter $D_c=1.43\sqrt{\frac{V}{P_0+1}},$ Wherein V is the volume flow of cutting gas under the status of criterion, P ₀Be converging portion import department gas pressure.The diameter of throat is determined by removing required cubical content of smear metal and stagnation pressure.

Described divergent section is divided into two sections, wherein determine by the special Meyer expansion line of the Blang under the isentropic conditions for first section, second section is adopted large diameter circular arc to make the slope of curve be decreased to 0 according to simplifying He Er (Hall) method for designing, and the General Definition arc diameter is large diameter circular arc more than 3 times greater than circular arc place pipe portion diameter.First section is positioned between throat and second section two sections smooth connections.

Described first section, its pattern curve is $\frac{R}{R_c}=1+x\tan \mathrm{\α}-A\tan \mathrm{\α}\arctan [\frac{x/R_c}{A}+0.03{\left(\frac{x}{A}\right)}^4],$ Wherein: $A=\frac{2}{\mathrm{\π}}(\cot \mathrm{\α}-3.686\sin \frac{\mathrm{\α}}{2}-\frac{0.48}{\sin (\mathrm{\α}/2)}+0.0048),$ α is the tangent line at curve any point x place and the angle of x axle, and the x axle is the central axis of nozzle, the α maximum between [9 °, 16 °], this moment the maximum x=L of place _t, i.e. first section end of divergent section, α is at x=L _tThe concrete size at place is determined by the annexation of divergent section outlet diameter and second section curve;

Described second section to make α by large diameter circular arc be 0 by the maximum transition, this moment diameter R _T=4～5D ₁, obtain by numerical method optimization.

Throat's design of existing superonic flow nozzzle mainly is with the large diameter circular arc transition according to Fu Ershi (Foelsch) method, then connect divergent section with straight line, but this method often can not guarantee the continuity of wall boundary layer growth, and can produce harmful effect to the divergent section flow field.The present invention is integrated throat and divergent section, and divergent section is divided into two sections of smooth binding, can not only guarantee that air-flow evenly quickens, and guarantee the continuity of wall boundary layer growth.

Compared with prior art, throat of the present invention is the transition section of being located between converging portion and the divergent section, and the realization of supersonic flow is all finished by divergent section, and the divergent section structure guarantees out that not only stream is even, and streamline is parallel, and can guarantee that the wall boundary layer is continuous.Divergent section of the present invention replaces complex curve with large diameter circular arc, and such design not only can greatly reduce difficulty of processing, and can guarantee machining accuracy.And the present invention is when cutting, and cutting effect is good, the speed height, and cut quality is good, and the joint-cutting lower limb does not have dross.When the difficult processing processing metal, the present invention can effectively blow away motlten metal and other high viscosity slag things especially, improves cut quality and cutting efficiency.Compare with the conically convergent structure nozzle of tradition, when operating pressure is 9.7bar, when nozzle and workpiece spacing 0.8mm, nozzle of the present invention improves 40% with cutting speed, or cutting thickness still can obtain the crudy better than traditional structure nozzle when increasing by 2 times.

Description of drawings

Fig. 1 is a nozzle arrangements cross-sectional schematic of the present invention

Fig. 2 is a nozzle inner walls curvilinear structures schematic diagram of the present invention

Fig. 3 is a converging portion curve synoptic diagram of the present invention

Fig. 4 is a divergent section general curve schematic diagram of the present invention

Fig. 5 is first section curve synoptic diagram of divergent section of the present invention

The specific embodiment

Below embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

As shown in Figure 1, present embodiment comprises: parallel-segment 1, converging portion 2, throat 3, divergent section 4, this four part is an integral body that communicates, wherein parallel-segment 1 import is connected the storage gases at high pressure with the external laser air cavity, parallel-segment 1 outlet connects the import of converging portion 2, converging portion 2 outlets connect throat 3, and throat's 3 opposite sides are divergent section 4, and throat 3 is for being located at the transition section between converging portion 2 and the divergent section 4.Gases at high pressure parallel-segment 1 and external cavity are by the storage gases at high pressure that are threaded, flow out gases at high pressure from parallel-segment 1, the converging portion 2 of flowing through accelerates to transonic flow, stream is finished transonic speed transition to supersonic flow through throat 3 again, at last in divergent section 4, supersonic flow continues expansion and reaches predetermined Mach number, and the guiding supersonic airstream stable and uniform that becomes.

The outside between described parallel-segment 1 and the converging portion 2 is provided with fixing and hermetically-sealed construction 6, and the sealing that is used for the gases at high pressure flow field is with fixing.

Described parallel-segment 1 entrance point is provided with linkage section 5, and linkage section 5 is whole nozzle and laser instrument air cavity coupling part, and employing is threaded.

Described parallel-segment 1, its diameter D ₀Depend on the 3 diameter D of throat _c, $D_0=D_c{\left[\frac{1}{M_0}{\left(\frac{1+0.2M_0^2}{1.2}\right)}^{\frac{k+1}{2(k-1)}}\right]}^{1/2},$ The general M that selects ₀=0.02～0.1.

Described throat 3 and divergent section 4 nearly wall streamline smooth transition.

As Fig. 2, shown in Figure 3, described converging portion 2, it is shaped as many Xin Jisi curve-like, guarantees that air-flow quickens to reach velocity of sound, keep again simultaneously flowing evenly with to go out streamline parallel.The Wei Duoxinjisi curved line relation is:

$R=\frac{R_c}{\sqrt{1-[1-{\left(\frac{R_c}{R_0}\right)}^2]\frac{{(1-{\left(\frac{x}{L_1}\right)}^2)}^2}{{(1+\frac{{\left(\frac{x}{L_1}\right)}^2}{3})}^3}}}$

X be on the axis more arbitrarily, L ₁Be the length of converging portion, R ₀, R _c, R is respectively converging portion 2 imports, outlet and the section radius at any x place.The advantage of Wei Duoxinjisi curve is that to guarantee to enter the air-flow of throat 3 even.

Described throat 3 is converted into ultrasonic transition interface zone with subsonic speed.As one, throat 3 is the transition section of converging portion 2 and divergent section 4 to present embodiment throat 3 and divergent section 4.Throat's 3 minimum diameters are by design pressure and the decision of environmental pressure level pressure ratio, and throat's 3 diameter of sections are $D_c=1.43\sqrt{\frac{V}{P_0+1}},$ V is the volume flow of cutting gas under the status of criterion, P ₀Be the 2 import department's gas pressures of converging portion shown in Fig. 3.The diameter of throat 3 is determined by removing required cubical content of smear metal and stagnation pressure.

As Fig. 4, shown in Figure 5, described divergent section 4 is designs of nozzles of the present invention cores, and the function of divergent section 4 is the air-flows that quicken to have reached in throat 3 velocity of sound by the expansion of gas, up to obtaining satisfied Mach number.The realization of supersonic flow is all finished by divergent section 4.

Described divergent section 4 designs are divided into two sections, comprise: first section 7 and second sections 8, the first sections 7 between throat 3 and second section 8, two sections smooth connections, promptly second section 8 large diameter circular arc initial angle equates with first section 7 curve end angle, guaranteed that supersonic domain wall boundary layer is uninterrupted.Determine that second section 8 is adopted large diameter circular arc to make the slope of curve be decreased to 0 according to simplifying He Er (Hall) method for designing for first section 7 by the special Meyer expansion line of the Blang under the isentropic conditions.

Described first section 7, its pattern curve is $\frac{R}{R_c}=1+x\tan \mathrm{\α}-A\tan \mathrm{\α}\arctan [\frac{x/R_c}{A}+0.03{\left(\frac{x}{A}\right)}^4],$

Wherein $A=\frac{2}{\mathrm{\π}}(\cot \mathrm{\α}-3.686\sin \frac{\mathrm{\α}}{2}-\frac{0.48}{\sin (\mathrm{\α}/2)}+0.0048),$ α is the tangent line at curve any point x place and the angle of x axle, the x axle is the central axis of nozzle, and the α size is between [9 °, 16 °], concrete size determines that by the annexation of outlet diameter and second section 8 curve R is the inner chamber radius of first section of curve any point x place divergent section.

Described second section 8 to make α by large diameter circular arc be 0 by the maximum transition, this moment diameter R _T=4～5D ₁R _TBe the radius of second section circular arc of divergent section, D ₁Be the divergent section outlet diameter, L _ERefer to divergent section second segment length.

The parallel-segment 1 of present embodiment and external cavity are by the storage gases at high pressure that are threaded, through converging portion 2 gases at high pressure are accelerated to transonic flow, make gasflow mach number reach 1, finish transonic speed transition through throat 3 to supersonic flow, reach predetermined Mach number and continue expansion at divergent section 4 supersonic flows, owing to first section 7 of divergent section 4 is to be come by Blang spy-Meyer expansion line match, gas can not clash into Gu Bi in the expansion accelerator, reflux and produce, but steadily push ahead, when gasflow mach number during near predetermined Mach number, air-flow enters 4 second section 8 of divergent section, by the large diameter circular arc guiding supersonic airstream stable and uniform that becomes, make the smooth transition of unparallel shaft linear flow line to the axis horizontal line, and can not influence the continuity of boundary layer growth.

Application example: utilize the high pressure nitrogen cutting stainless steel

Designs of nozzles outlet Mach 2 ship 2.0878 of the present invention, stainless-steel sheet thickness is 4mm, the trade mark is 316L, and laser power is 2000W, and the distance between nozzle and the workpiece is 0.8mm, gas pressure is 11.2bar, focus is 0.875mm to the distance of surface of the work, and cutting speed is for getting 3.0m/min, 4.0m/min respectively, 5.0m/min, the following expression of cutting test result:

Cutting speed (m/min)	Upper surface seam wide (mm)	Lower surface seam wide (mm)	The inclination angle (°)	Dross	Roughness Ra (μ m)
						3.0	0.26	0.2	0.4297	No	2.1
4.0	0.24	0.19	0.3581	Seldom	2.6
						5.0	0.22	0.17	0.3581	Seldom	2.9

From last table result of the test more as can be seen.The kerf width of upper and lower surface is very little, and the inclination angle is also very little simultaneously, and the otch section is smooth and smooth.And utilize traditional nozzle to cut the thick stainless steel of 4mm, orifice gas pressure could blow away motlten metal and slag inclusion thereof when 17.6bar from joint-cutting, and there is burr in the otch, perpendicularity is relatively poor, so the superonic flow nozzzle cutting with the design can not only obtain good cut quality, and can reduce gas consumption.

Claims (9)

1. superonic flow nozzzle that is used for laser cutting, comprise: parallel-segment, converging portion, throat, divergent section, this four part is an integral body that communicates, wherein: the import of parallel-segment is connected with the external laser air cavity, both are used to store gases at high pressure jointly, the parallel-segment outlet connects the import of converging portion, the converging portion outlet connects throat, throat's opposite side is a divergent section, it is characterized in that: described throat is the transition section of being located between converging portion and the divergent section, described divergent section comprises first section and second section, two sections smooth connections, first section is positioned between throat and second section, is determined by the Blang spy under the isentropic conditions-Meyer expansion line for first section, second section He Er method for designing according to simplification adopts large diameter circular arc to make the slope of curve be decreased to 0;

Described large diameter circular arc is meant that arc diameter is greater than more than 3 times of circular arc place pipe portion diameter.

2. the superonic flow nozzzle that is used for laser cutting according to claim 1 is characterized in that, first section of described divergent section, and its pattern curve is:

$\frac{R}{R_c}=1+x\tan \mathrm{\α}-A\tan \mathrm{\α}\arctan [\frac{x/R_c}{A}+0.03{\left(\frac{x}{A}\right)}^4],$

Wherein $A=\frac{2}{\mathrm{\π}}(\cot \mathrm{\α}-3.686\sin \frac{\mathrm{\α}}{2}-\frac{0.48}{\sin (\mathrm{\α}/2)}+0.0048),$ The α size is between [9 °, 16 °], and X-axis is the central axis of nozzle, and α is the tangent line at any point x place on the curve and the angle of X-axis, and R is the inner chamber radius at curve any point x place, R _cIt is the section radius of converging portion outlet.

3. the superonic flow nozzzle that is used for laser cutting according to claim 1 is characterized in that, it is 0 by the maximum transition that second section of described divergent section makes α by large diameter circular arc, this moment diameter R _T=4～5D ₁, length is L _E, the α size is between [9 °, 16 °], and α is the tangent line at curve any point x place and the angle of X-axis, R _TBe the radius of second section circular arc of divergent section, D ₁Be the divergent section outlet diameter, L _ERefer to divergent section second segment length.

4. the superonic flow nozzzle that is used for laser cutting according to claim 1 is characterized in that, described throat, and its minimum diameter is by design pressure and the decision of environmental pressure level pressure ratio, throat section diameter $D_c=1.43\sqrt{\frac{V}{P_0+1}},$ Wherein V is the volume flow of cutting gas under the status of criterion, P ₀Be converging portion import department gas pressure.

5. the superonic flow nozzzle that is used for laser cutting according to claim 1 is characterized in that, the outside between described parallel-segment and the converging portion is provided with fixing and hermetically-sealed construction, and the sealing that is used for the gases at high pressure flow field is with fixing.

6. be used for the superonic flow nozzzle of laser cutting according to claim 1 or 5, it is characterized in that, described parallel-segment entrance point is provided with linkage section, and linkage section is connected with the laser instrument air cavity by screw thread.

7. be used for the superonic flow nozzzle of laser cutting according to claim 1 or 5, it is characterized in that, described parallel-segment, its diameter of section D ₀Depend on throat section diameter D _c, $D_0=D_c{\left[\frac{1}{M_0}{\left(\frac{1+{0.2M}_0^2}{1.2}\right)}^{\frac{k+1}{2(k-1)}}\right]}^{1/2},$ M ₀Be converging portion inlet Mach number, M ₀=0.02～0.1, k is the gas adiabatic coefficent.

8. the superonic flow nozzzle that is used for laser cutting according to claim 1 is characterized in that, the nearly wall streamline of described throat and divergent section smooth transition.

9. the superonic flow nozzzle that is used for laser cutting according to claim 1 is characterized in that, described converging portion, and it is shaped as the Wei Duoxinjisi curve-like.

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