Laser cutting device and laser cutting method

Abstract

The present invention provides a laser cutting device and a laser cutting method, which include an auxiliary gas control unit, a laser generating unit and a gas self-excited oscillation unit. The auxiliary gas control unit is connected to the side wall of the gas self-excited oscillation unit, and the focusing lens in the laser generating unit is embedded in the Helmholtz cavity of the gas self-excited oscillation unit. The auxiliary gas control unit is used to input the auxiliary gas into the Helmholtz cavity of the gas self-excited oscillation unit, the laser generating unit is used to focus the laser beam and pass it through the Helmholtz cavity of the gas self-excited oscillation unit, and the gas self-excited oscillation unit is used to enable the auxiliary gas to achieve periodic changes in gas flow in the Helmholtz cavity. The present invention enables the auxiliary gas to achieve self-oscillation pulses and periodic changes in gas flow through the gas self-excited oscillation unit, thereby effectively improving the processing efficiency of the laser cutting device.

Description

Technical Field

[0001] The present invention relates to the field of laser cutting, and in particular to a laser cutting device and a laser cutting method. Background Art

[0002] Laser cutting is a process in which a laser beam passes through a focusing lens, concentrating its energy at a focal point and generating high-density energy. Upon reaching the surface of the material, a light spot is formed, where the material absorbs heat and rapidly melts to form a molten material, or even vaporizes. The molten material flows out of the incision under the dual effects of gravity and the dynamics of the auxiliary airflow, thereby achieving material removal. As the laser beam moves, non-contact, high-speed, and high-precision cutting is achieved. However, existing laser cutting technology lacks special devices to achieve pulsed air intake, and during the cutting process, the auxiliary gas escapes in large quantities radially along the nozzle. There are no effective measures to fully utilize the auxiliary gas, resulting in relatively low processing efficiency on the surface of the workpiece being processed.

[0003] Therefore, there is an urgent need for a laser cutting device and a laser cutting method to solve the above technical problems. Summary of the Invention

[0004] The object of the present invention is to provide a laser cutting device and a laser cutting method, so as to improve the technical problem of low processing efficiency existing in the laser cutting device of the prior art.

[0005] To solve the above technical problems, the present invention provides a laser cutting device, comprising an auxiliary gas control unit, a laser generating unit, and a gas self-excited oscillation unit, wherein the auxiliary gas control unit is connected to the side wall of the gas self-excited oscillation unit, and the focusing lens in the laser generating unit is embedded in the Helmholtz cavity of the gas self-excited oscillation unit;

[0006] Among them, the auxiliary gas control unit is used to input the auxiliary gas into the Helmholtz cavity of the gas self-excited oscillation unit, the laser generating unit is used to focus the laser beam and pass it through the Helmholtz cavity of the gas self-excited oscillation unit, and the gas self-excited oscillation unit is used to enable the auxiliary gas to achieve periodic changes in the gas flow in the Helmholtz cavity.

[0007] In the laser cutting device provided in an embodiment of the present invention, the auxiliary gas control unit includes a gas cylinder assembly, an air compressor assembly connected to the gas cylinder assembly, an electromagnetic throttle valve assembly connected to the air compressor assembly, and a control system electrically connected to the electromagnetic throttle valve assembly;

[0008] Among them, the gas cylinder assembly is used to load auxiliary gas, the air compressor assembly is used to compress the auxiliary gas, and the control system is used to adjust the flow of the auxiliary gas through the electromagnetic throttle valve assembly.

[0009] In the laser cutting device provided in an embodiment of the present invention, the gas cylinder assembly includes a first gas cylinder for carrying a first gas, a second gas cylinder for carrying a second gas, and a third gas cylinder for carrying a third gas; the air compressor assembly includes a first air compressor, a second air compressor, and a third air compressor; and the electromagnetic throttle valve assembly includes a first electromagnetic throttle valve, a second electromagnetic throttle valve, and a third electromagnetic throttle valve;

[0010] Among them, the inlet of the first air compressor is connected to the first gas cylinder, the outlet of the first air compressor is connected to the inlet of the first electromagnetic throttle valve, the inlet of the second air compressor is connected to the second gas cylinder, and the outlet of the second air compressor is connected to the inlet of the second electromagnetic throttle valve; the inlet of the third air compressor is connected to the third gas cylinder, and the outlet of the third air compressor is connected to the inlet of the third electromagnetic throttle valve; the outlet of the first electromagnetic throttle valve, the outlet of the second electromagnetic throttle valve and the outlet of the third electromagnetic throttle valve are all connected to the side wall of the gas self-excited oscillation unit.

[0011] In the laser cutting device provided in the embodiment of the present invention, the gas self-excited oscillation unit includes a Helmholtz upper nozzle, which is a hollow cylindrical thin-walled structure and has no upper cylindrical surface;

[0012] The focusing lens is embedded in the Helmholtz upper nozzle, and the diameter of the focusing lens is the same as the diameter of the Helmholtz upper nozzle.

[0013] In the laser cutting device provided by the embodiment of the present invention, two bosses are symmetrically provided at the center of the cylindrical side surface of the Helmholtz upper nozzle, and each boss is provided with a first through hole;

[0014] The outlet of the first electromagnetic throttle valve, the outlet of the second electromagnetic throttle valve and the outlet of the third electromagnetic throttle valve are all connected to the first through hole.

[0015] In the laser cutting device provided in an embodiment of the present invention, the gas self-excited oscillation unit further includes a Helmholtz lower nozzle threadedly connected to the Helmholtz upper nozzle, the Helmholtz lower nozzle being a cylindrical rotating body structure, and a second through hole is formed on the lower cylindrical surface of the Helmholtz lower nozzle;

[0016] A third through hole is formed on the lower cylindrical surface of the Helmholtz upper nozzle, and a diameter of the second through hole is greater than a diameter of the third through hole.

[0017] In the laser cutting device provided by an embodiment of the present invention, the laser generating unit further includes a laser generator, the laser generator is used to emit a first laser beam to a focusing lens, and the focusing lens is used to focus the first laser beam into a second laser beam;

[0018] The second laser beam passes through the third through hole and the second through hole in sequence.

[0019] In the laser cutting device provided in an embodiment of the present invention, the resonant cavity length for achieving the best self-oscillation effect of the gas self-oscillation unit is L+L1-k, where L is the distance from the lower surface of the Helmholtz upper nozzle to the upper end of the collision wall of the Helmholtz lower nozzle, L1 is the neck length of the Helmholtz lower nozzle, and k is the wall thickness of the lower end surface of the Helmholtz lower nozzle;

[0020] Among them, the value of L satisfies Formula 1 to Formula 6:

[0021] Formula 1:

[0022] Formula 2:

[0023] Formula 3:

[0024] Formula 4:

[0025] Formula 5: f = f H ;

[0026] Formula 6: s = 0.3;

[0027] f H is the natural frequency of the Helmholtz cavity, a is the local sound velocity, A is the cross-sectional area of ​​the Helmholtz upper nozzle, V is the volume of the Helmholtz cavity, l is the neck length of the Helmholtz upper nozzle, s is the Strouhal number, f is the oscillation frequency, and U is the jet velocity; d is the diameter of the Helmholtz cavity, d1 is the diameter of the third through hole, d2 is the diameter of the second through hole, and D is the jet diameter, which is equal to d1;

[0028] Among them, d, d1, d2, L1, l and k are determined by the factory parameters of the Helmholtz chamber, and U is calculated based on the preset flow rate of the electromagnetic throttle valve assembly and the preset air pressure of the air compressor assembly in combination with the gas Bernoulli equation.

[0029] In the laser cutting device provided in the embodiment of the present invention, the laser cutting device further comprises an air baffle unit threadedly connected to the Helmholtz lower nozzle, the air baffle unit comprising an air baffle hood, the air baffle hood being a cylindrical thin-walled structure without upper and lower end surfaces;

[0030] The distance that the air shield extends beyond the lower end surface of the Helmholtz lower nozzle is smaller than the distance between the surface of the workpiece being processed and the lower end surface of the Helmholtz lower nozzle.

[0031] Accordingly, the present invention further provides a laser cutting method, which is implemented by the laser cutting device as described in any one of the above items, and the method comprises:

[0032] Connect the circuit of the auxiliary gas control unit and adjust the flow of the auxiliary gas through the electromagnetic throttle valve assembly so that the auxiliary gas flows into the Helmholtz upper nozzle according to the preset ratio;

[0033] The circuit of the laser generating unit is turned on to enable the laser generator to generate a laser beam. The laser beam is focused by the focusing lens and passes through the third through hole of the Helmholtz upper nozzle and the second through hole of the Helmholtz lower nozzle in sequence, and finally the high-energy light spot reaches the surface of the workpiece to be processed;

[0034] Adjust the resonant cavity length of the Helmholtz cavity to achieve the best self-oscillation effect of the Helmholtz cavity;

[0035] Adjust the distance that the air deflector hood exceeds the lower end surface of the Helmholtz lower nozzle so that the actual effective length of the air deflector hood is smaller than the distance between the surface of the workpiece being processed and the lower end surface of the Helmholtz lower nozzle.

[0036] The beneficial effects of the present invention are: different from the prior art, the present invention provides a laser cutting device and a laser cutting method, including an auxiliary gas control unit, a laser generating unit and a gas self-excited oscillation unit, the auxiliary gas control unit is connected to the side wall of the gas self-excited oscillation unit, and the focusing lens in the laser generating unit is embedded in the Helmholtz cavity of the gas self-excited oscillation unit, wherein the auxiliary gas control unit is used to input the auxiliary gas into the Helmholtz cavity of the gas self-excited oscillation unit, the laser generating unit is used to focus the laser beam and pass through the Helmholtz cavity of the gas self-excited oscillation unit, and the gas self-excited oscillation unit is used to enable the auxiliary gas to achieve periodic changes in the gas flow rate in the Helmholtz cavity; the laser cutting device provided by the present invention adds a gas self-excited oscillation unit connected to the auxiliary gas control unit, so that the auxiliary gas can achieve self-oscillation pulses and achieve periodic changes in the gas flow rate. The periodic changes in the auxiliary gas flow rate ensure that the laser energy is not too large for a long time, causing ablation damage to the workpiece being processed, while effectively improving the processing efficiency of the laser cutting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of the laser cutting device provided by an embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of Helmholtz cavity parameters in a laser cutting device provided by an embodiment of the present invention;

[0039] Figure 3This is a comparison chart of the processing effects of the laser cutting device provided by an embodiment of the present invention and the laser cutting device of the prior art;

[0040] Figure 4 This is a line graph comparing the cross-sectional slag area of ​​the laser cutting device provided by an embodiment of the present invention and the laser cutting device of the prior art;

[0041] Figure 5 It is a process flow chart of the laser cutting method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] See also Figures 1 to 4 The present invention provides a laser cutting device 100 and a laser cutting method, comprising an auxiliary gas control unit 10, a laser generating unit 20, and a gas self-excited oscillation unit 30. The auxiliary gas control unit 10 is connected to a side wall of the gas self-excited oscillation unit 30. The focusing lens 202 in the laser generating unit 20 is embedded in a Helmholtz cavity 31 of the gas self-excited oscillation unit 30.

[0044] Among them, the auxiliary gas control unit 10 is used to input the auxiliary gas into the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, the laser generating unit 20 is used to focus the laser beam and pass through the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, and the gas self-excited oscillation unit 30 is used to enable the auxiliary gas to achieve periodic changes in the gas flow in the Helmholtz cavity 31.

[0045] The laser cutting device 100 provided by the present invention adds a gas self-excited oscillation unit 30 connected to the auxiliary gas control unit 10, so that the auxiliary gas can realize self-oscillation pulses and realize periodic changes in the gas flow rate. The periodic changes in the auxiliary gas flow rate ensure that the laser energy is not too large for a long time, causing ablation damage to the workpiece being processed, while effectively improving the processing efficiency of the laser cutting device 100.

[0046] The technical solution of this application is now described in conjunction with specific embodiments.

[0047] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of the laser cutting device 100 provided in an embodiment of the present invention; Figure 2 , Figure 2 Schematic diagram of the parameters of the Helmholtz cavity 31 in the laser cutting device 100 provided in an embodiment of the present invention; wherein the laser cutting device 100 includes an auxiliary gas control unit 10, a laser generating unit 20, and a gas self-excited oscillation unit 30, the auxiliary gas control unit 10 is connected to the side wall of the gas self-excited oscillation unit 30, and the focusing lens 202 in the laser generating unit 20 is embedded in the Helmholtz cavity 31 of the gas self-excited oscillation unit 30;

[0048] Among them, the auxiliary gas control unit 10 is used to input the auxiliary gas into the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, the laser generating unit 20 is used to focus the laser beam and pass through the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, and the gas self-excited oscillation unit 30 is used to enable the auxiliary gas to achieve periodic changes in the gas flow in the Helmholtz cavity 31.

[0049] In the embodiment of the present invention, the auxiliary gas control unit 10 includes a gas cylinder assembly 11, an air compressor assembly 12 connected to the gas cylinder assembly 11, an electromagnetic throttle valve assembly 13 connected to the air compressor assembly 12, and a control system 107 electrically connected to the electromagnetic throttle valve assembly 13;

[0050] The gas cylinder assembly 11 is used to load auxiliary gas, the air compressor assembly 12 is used to compress the auxiliary gas, and the control system 107 is used to adjust the flow of the auxiliary gas through the electromagnetic throttle valve assembly 13.

[0051] See also Figure 1 The gas cylinder assembly 11 includes a first gas cylinder 101 for loading a first gas, a second gas cylinder 102 for loading a second gas, and a third gas cylinder 103 for loading a third gas. The air compressor assembly 12 includes a first air compressor 104, a second air compressor 105, and a third air compressor 106. The electromagnetic throttle valve assembly 13 includes a first electromagnetic throttle valve 108, a second electromagnetic throttle valve 109, and a third electromagnetic throttle valve 110.

[0052] Among them, the inlet of the first air compressor 104 is connected to the first gas cylinder 101, the outlet of the first air compressor 104 is connected to the inlet of the first electromagnetic throttle valve 108, the inlet of the second air compressor 105 is connected to the second gas cylinder 102, and the outlet of the second air compressor 105 is connected to the inlet of the second electromagnetic throttle valve 109; the inlet of the third air compressor 106 is connected to the third gas cylinder 103, and the outlet of the third air compressor 106 is connected to the inlet of the third electromagnetic throttle valve 110; the outlet of the first electromagnetic throttle valve 108, the outlet of the second electromagnetic throttle valve 109 and the outlet of the third electromagnetic throttle valve 110 are all connected to the side wall of the gas self-excited oscillation unit 30.

[0053] Specifically, the gas components of the first gas, the second gas and the third gas are all different, and the first gas, the second gas and the third gas are all selected from any one of oxygen, nitrogen, air, argon and other inert gases.

[0054] Specifically, the outlet of the first electromagnetic throttle valve 108, the outlet of the second electromagnetic throttle valve 109 and the outlet of the third electromagnetic throttle valve 110 are merged into one pipeline, and the control system 107 is electrically connected to the first electromagnetic throttle valve 108, the second electromagnetic throttle valve 109 and the third electromagnetic throttle valve 110 respectively to control the flow parameters of the above-mentioned electromagnetic throttle valve assembly 13.

[0055] See also Figure 1 In the laser cutting device 100 provided by the embodiment of the present invention, the gas self-excited oscillation unit 30 includes a Helmholtz upper nozzle 301. The Helmholtz upper nozzle 301 is a hollow cylindrical thin-walled structure. The Helmholtz upper nozzle 301 has no upper cylindrical surface.

[0056] The focusing lens 202 is embedded in the Helmholtz upper nozzle 301 , and the diameter of the focusing lens 202 is the same as the diameter of the Helmholtz upper nozzle 301 . This design can ensure the stability and airtightness of the fixation between the focusing lens 202 and the Helmholtz upper nozzle 301 .

[0057] In the laser cutting device 100 provided by the embodiment of the present invention, two bosses 3011 are symmetrically provided at the center of the cylindrical side surface of the Helmholtz upper nozzle 301, and each boss 3011 is provided with a first through hole 32;

[0058] The outlet of the first electromagnetic throttle valve 108 , the outlet of the second electromagnetic throttle valve 109 and the outlet of the third electromagnetic throttle valve 110 form a three-in-one pipeline, and the three-in-one pipeline is connected to the first through holes 32 corresponding to the two bosses 3011 .

[0059] In the laser cutting device 100 provided by the embodiment of the present invention, the gas self-excited oscillation unit 30 further includes a Helmholtz lower nozzle 302 threadedly connected to the Helmholtz upper nozzle 301. The Helmholtz lower nozzle 302 is Figure 1 The shape is a cylindrical rotating body structure obtained by rotating one circle around the central axis, and the lower cylindrical surface of the Helmholtz lower nozzle 302 is provided with a second through hole 33;

[0060] A third through hole 34 is defined on the lower cylindrical surface of the Helmholtz upper nozzle 301 , and a diameter d2 of the second through hole 33 is greater than a diameter d1 of the third through hole 34 .

[0061] In the laser cutting device 100 provided in the embodiment of the present invention, the laser generating unit 20 further includes a laser generator 201, which is used to emit a first laser beam to a focusing lens 202, and the focusing lens 202 is used to focus the first laser beam into a second laser beam;

[0062] The second laser beam passes through the third through hole 34 and the second through hole 33 in sequence to reach the surface of the workpiece being processed.

[0063] See also Figure 2 Since the Helmholtz upper nozzle 301 and the Helmholtz lower nozzle 302 are threadedly connected, the distance L between the upper and lower Helmholtz nozzles is adjusted by tightening the threads deeply or shallowly, so as to facilitate adjustment of the optimal resonance cavity length of the Helmholtz cavity 31; at the same time, the airtightness of the connection between the Helmholtz upper nozzle 301 and the Helmholtz lower nozzle 302 is ensured by wrapping the raw tape outside.

[0064] See also Figure 1 as well as Figure 2 In the laser cutting device 100 provided by the embodiment of the present invention, the self-oscillation effect of the Helmholtz cavity 31 is optimal when the oscillation frequency of the Helmholtz cavity 31 is equal to its natural frequency and the Strouhal number is 0.3. The Strouhal number is a similarity criterion that characterizes the periodicity of a flow. When studying vortex streets, rotors, propellers, and flutter, aerodynamic phenomena are related to the frequency of periodic motion. Therefore, the Strouhal number should be equal in model experiments and in actual flight.

[0065] Specifically, see Figure 1 as well as Figure 2 The length of the resonance cavity for achieving the best self-oscillation effect of the gas self-oscillation unit 30 is L+L1-k, where L is the distance from the lower surface of the Helmholtz upper nozzle 301 to the upper end of the collision wall of the Helmholtz lower nozzle 302, L1 is the neck length of the Helmholtz lower nozzle 302, and k is the wall thickness of the lower end surface of the Helmholtz lower nozzle 302;

[0066] Among them, the value of L satisfies Formula 1 to Formula 6:

[0067] Formula 1:

[0068] Formula 2:

[0069] Formula 3:

[0070] Formula 4:

[0071] Formula 5: f = f H ;

[0072] Formula 6: s = 0.3;

[0073] f H is the natural frequency of the Helmholtz cavity 31, a is the local sound velocity, A is the cross-sectional area of ​​the Helmholtz upper nozzle 301, V is the volume of the Helmholtz cavity 31, l is the neck length of the Helmholtz upper nozzle 301, s is the Strouhal number, f is the oscillation frequency, and U is the jet velocity; d is the diameter of the Helmholtz cavity 31, d1 is the diameter of the third through hole 34, d2 is the diameter of the second through hole 33, and D is the jet diameter, which is equal to d1;

[0074] Among them, d, d1, d2, L1, l and k are determined by the factory parameters of the Helmholtz chamber 31, and U is calculated based on the preset flow Q of the electromagnetic throttle valve assembly 13 and the preset air pressure P of the air compressor assembly 12 in combination with the gas Bernoulli equation.

[0075] See also Figure 1 The laser cutting device 100 also includes an air blocking unit 40 threadedly connected to the Helmholtz lower nozzle 302. The air blocking unit 40 includes an air blocking hood 41. The air blocking hood 41 is a cylindrical thin-walled structure. The air blocking hood 41 has no upper and lower end faces and is connected to the Helmholtz lower nozzle 302 through threads. The air tightness of the connection is ensured by wrapping the raw tape around it.

[0076] Specifically, the air baffle 41 is connected to the Helmholtz lower nozzle 302 through threads, and the air tightness of the connection is ensured by wrapping it with raw tape. The actual effective length of the air baffle 41 is adjusted by tightening the threads deeply or shallowly, and the length is made slightly smaller than the distance from the overall structure of the Helmholtz lower nozzle 302 to the surface of the workpiece being processed.

[0077] In the embodiment of the present invention, the gas self-excited oscillation unit 30 enables the auxiliary gas to achieve self-oscillation pulses and realize periodic changes in gas flow rate. The working principle is as follows:

[0078] The gas self-excited oscillation unit 30 operates on a similar principle to a Helmholtz oscillator. A first laser beam is emitted from a laser generator 201 and directed to a focusing lens 202. This laser beam is focused by the focusing lens 202 to form a second laser beam. The second laser beam, acting upon the auxiliary gas within the Helmholtz cavity 31 corresponding to the upper Helmholtz nozzle 301, creates surface disturbances, forming a series of vortex rings. These vortex rings then strike the collision wall of the lower Helmholtz nozzle 302, generating pressure pulses. These pressure pulses accelerate the fluid in front of the vortex rings while decelerating the fluid behind them.

[0079] When the pressure shock wave propagates to the Helmholtz upper nozzle 301 at the speed of sound in the opposite direction of the jet, it collides with the outlet wall of the Helmholtz upper nozzle 301 to form a pressure pulse again. On the one hand, this pressure pulse causes the fluid pressure in the Helmholtz upper nozzle 301 to oscillate, inducing the generation of a new vortex, and on the other hand, it propagates downward along the jet. If the reflected wave arrives at the collision wall of the Helmholtz lower nozzle 302 at the same time as a certain vortex, the pressure pulse generated by the collision is strengthened. This cycle is repeated to form a positive feedback closed loop, which amplifies the vortex to form a large vortex structure. The change law of the vacuum degree in the Helmholtz cavity 31 is directly related to the structural size, vortex frequency and amplitude of the Helmholtz cavity 31. When the oscillation frequency of the Helmholtz cavity 31 is equal to the natural frequency of the Helmholtz cavity 31, the vortex is amplified, causing the jet pressure and velocity to pulsate significantly, forming a strong pulse jet. At this time, the self-excited oscillation effect of the Helmholtz cavity 31 is best.

[0080] See also Figure 3 , Figure 3 This is a comparison chart of the processing effects of the laser cutting device 100 provided by the embodiment of the present invention and the laser cutting device 100 of the prior art; among them, it can be seen from the above three groups of comparative experiments that the laser cutting device 100 provided by the embodiment of the present invention has better processing effects than the prior art; this is because the laser cutting device 100 provided by the embodiment of the present invention, due to the periodic change of the auxiliary gas flow rate, ensures that the laser energy is not too large for a long time, causing ablation damage to the workpiece, and also ensures a certain processing efficiency.

[0081] See also Figure 4 , Figure 4 The cross-sectional slag area comparison line graph of the laser cutting device 100 provided by the embodiment of the present invention and the laser cutting device 100 of the prior art is shown in FIG. 1 , wherein the horizontal axis is the gas pressure (MPa) and the vertical axis is the slag area of ​​the workpiece being processed (mm 2), the pulse mode of the gas self-excited oscillation unit 30 is: pulse power is 150W*60%, and pulse speed is 150mm / min.

[0082] Depend on Figure 4 It can be seen that the laser cutting device 100 provided in the embodiment of the present invention makes the surface of the processed workpiece have a smaller slag area than the prior art; this is because the laser cutting device 100 provided in the embodiment of the present invention has an additional gas shield 41, which can make the airflow of the auxiliary gas more concentrated, and the gas flow rate through the cutting seam is higher, so that the auxiliary gas can be fully utilized, and at the same time the slag area at the sharp corners can be reduced.

[0083] Correspondingly, the present invention also provides a laser cutting method, which is implemented by the laser cutting device 100 as described in any one of the above items.

[0084] Specifically, see Figure 1 、 Figure 2 as well as Figure 5 , Figure 5 This is a process flow chart of the laser cutting method provided by an embodiment of the present invention. The above method specifically includes:

[0085] S10 , connecting the circuit of the auxiliary gas control unit 10 , and adjusting the flow of the auxiliary gas through the electromagnetic throttle valve assembly 13 , so that the auxiliary gas flows into the Helmholtz upper nozzle 301 according to a preset ratio.

[0086] Specifically, S10 also includes:

[0087] The circuit of the auxiliary gas control unit 10 is turned on, and the flow parameters of the first electromagnetic throttle valve 108, the second electromagnetic throttle valve 109 and the third electromagnetic throttle valve 110 are adjusted through the control system 107 according to processing requirements, so that the different auxiliary gases in the auxiliary gas control unit 10 are introduced into the Helmholtz upper nozzle 301 according to the preset ratio.

[0088] S20, turning on the circuit of the laser generating unit 20, causing the laser generator 201 to generate a laser beam, which is focused by the focusing lens 202 and passes through the third through hole 34 of the Helmholtz upper nozzle 301 and the second through hole 33 of the Helmholtz lower nozzle 302 in sequence, ultimately allowing the high-energy light spot to reach the surface of the workpiece being processed.

[0089] Specifically, the S20 also includes:

[0090] The circuit of the laser generating unit 20 is turned on, so that the laser generator 201 generates a first laser beam. The first laser beam is focused by the focusing lens 202 to form a second laser beam. The second laser beam passes through the third through hole 34 of the Helmholtz upper nozzle 301 and the second through hole 33 of the Helmholtz lower nozzle 302, and finally the high-energy light spot reaches the processing surface.

[0091] S30, adjusting the resonant cavity length of the Helmholtz cavity 31 to optimize the self-oscillation effect of the Helmholtz cavity 31.

[0092] Specifically, S30 also includes:

[0093] Adjust the thread connecting the Helmholtz upper nozzle 301 and the Helmholtz lower nozzle 302 to ensure that the distance L between the upper and lower Helmholtz nozzles reaches a preset length (the preset length is calculated by Formulas 1 to 6) so that the resonant cavity length of the Helmholtz cavity 31 (the resonant cavity length is L+L1-k) is at an optimal length, thereby achieving the best self-oscillation pulse effect of the Helmholtz cavity 31.

[0094] S40 , adjusting the distance of the air deflector 41 beyond the lower end surface of the Helmholtz lower nozzle 302 so that the actual effective length of the air deflector 41 is smaller than the distance between the surface of the workpiece and the lower end surface of the Helmholtz lower nozzle 302 .

[0095] Specifically, S40 also includes:

[0096] Adjust the thread connecting the Helmholtz lower nozzle 302 and the air deflector 41 to ensure that the distance the air deflector 41 extends beyond the lower end face of the Helmholtz lower nozzle 302 is slightly smaller than the distance between the surface of the workpiece being processed and the lower end face of the Helmholtz lower nozzle 302, that is, to ensure that the air deflector 41 does not generate friction with the surface of the workpiece being processed.

[0097] In the laser cutting method provided in an embodiment of the present invention, the outlet of the first electromagnetic throttle valve 108, the outlet of the second electromagnetic throttle valve 109 and the outlet of the third electromagnetic throttle valve 110 are merged into one pipeline, which is then divided into two pipelines and respectively connected to the first through holes 32 on the two side bosses 3011 of the Helmholtz upper nozzle 301, ensuring that the sum of the flow rates passing through the three outlets is equal to the maximum flow value of one pipeline.

[0098] Specifically, depending on actual needs, one or both pipelines can be closed, allowing only a mixture of two gases or a single gas to flow. When focusing on processing speed but not cutting quality, or when processing thick workpieces, the proportion of oxygen can be appropriately increased. When focusing on processing quality but not cost, the proportion of nitrogen can be increased, or even argon can be used as a shielding gas. When lowering processing costs is required, compressed air can be used alone as the auxiliary gas.

[0099] Furthermore, in order to achieve a balance between cutting quality and processing speed, the flow parameters of the first electromagnetic throttle valve 108, the second electromagnetic throttle valve 109 and the third electromagnetic throttle valve 110 can be adjusted through the control system 107 to continuously change the ratio of oxygen and inert gas. When it is observed that the cutting effect meets the requirements, the change of the air intake ratio can be stopped.

[0100] In the laser cutting method provided in an embodiment of the present invention, since the laser cutting device 100 is added with a gas self-excited oscillation unit 30 similar to a Helmholtz oscillator, the auxiliary gas can realize self-oscillation pulses and realize periodic changes in the gas flow rate. When the auxiliary gas is oxygen and low-flow etching acts on the workpiece to be processed, the laser processing ablation ability is weakened, avoiding damage to the workpiece to be processed; when high-flow etching acts on the workpiece to be processed, the laser processing ability is significantly enhanced. Since oxygen assists combustion, the cutting energy is large, so the processing speed is fast. The periodic change of the flow rate not only ensures that the laser energy is not too large for a long time, causing ablation damage to the workpiece, but also ensures a certain processing efficiency.

[0101] In the laser cutting method provided in the embodiment of the present invention, the laser cutting device 100 with the air shield 41 can make the airflow more concentrated, increase the gas flow rate through the cutting seam, make full use of the auxiliary gas, and reduce the slag area at the sharp corners.

[0102] In the embodiment of the present invention, a gas self-excited oscillation unit 30 similar to a Helmholtz oscillator is added, so that the auxiliary gas can realize self-pulsation, thereby realizing the auxiliary gas controllable self-pulsation laser cutting device 100 with periodic changes in gas flow.

[0103] Furthermore, the embodiment of the present invention also provides an auxiliary gas control unit 10 with an adjustable auxiliary gas intake ratio, and an auxiliary gas controllable laser cutting device 100 with different intake modes can be selected for different working conditions.

[0104] Furthermore, in the embodiment of the present invention, the addition of the air blocking unit 40 makes the air flow more concentrated, the gas flow rate through the slit is higher, the auxiliary gas is fully utilized, and the slag area at the sharp corner can be reduced.

[0105] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0106] First, the addition of a gas self-excited oscillation unit 30, similar to a Helmholtz oscillator, enables the auxiliary gas to self-pulse, achieving periodic changes in gas flow. When the auxiliary gas is oxygen and the flow rate is low, the laser's ablation capability is weakened, preventing damage to the workpiece. When the flow rate is high, the laser's processing capability is significantly enhanced. Because oxygen assists combustion, the cutting energy is high, resulting in faster processing speeds. This periodic change in flow rate prevents excessive laser energy from causing ablation damage to the workpiece while maintaining a certain level of processing efficiency.

[0107] Second, the auxiliary gas intake ratio is adjustable, which has obvious advantages when processing different materials. When pursuing processing speed but not requiring cutting quality, the oxygen ratio can be appropriately increased; when pursuing processing quality and not requiring cost, the nitrogen ratio can be increased or even argon can be used as a shielding gas; when lower processing costs are required, compressed air can be selected as the auxiliary gas; in order to achieve a balance between cutting quality and processing speed, the electromagnetic throttle valve can be adjusted to make the ratio of oxygen and inert gas change continuously. When it is observed that the cutting effect meets the requirements, the intake ratio can be stopped.

[0108] Third, the improved nozzle with the air shield 41 can make the airflow more concentrated, the gas flow rate through the slit is higher, the auxiliary gas is fully utilized, and the slag area at the sharp corner can be reduced.

[0109] In summary, different from the prior art, the present invention provides a laser cutting device 100 and a laser cutting method, including an auxiliary gas control unit 10, a laser generating unit 20 and a gas self-excited oscillation unit 30, the auxiliary gas control unit 10 is connected to the side wall of the gas self-excited oscillation unit 30, and the focusing lens 202 in the laser generating unit 20 is embedded in the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, wherein the auxiliary gas control unit 10 is used to input the auxiliary gas into the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, and the laser generating unit 20 is used to input the laser beam After focusing, the light passes through the Helmholtz cavity 31 of the gas self-excited oscillation unit 30, and the gas self-excited oscillation unit 30 is used to enable the auxiliary gas to achieve periodic changes in the gas flow in the Helmholtz cavity 31; the laser cutting device 100 provided by the present invention adds a gas self-excited oscillation unit 30 connected to the auxiliary gas control unit 10, so that the auxiliary gas can achieve self-oscillation pulses and achieve periodic changes in the gas flow. The periodic changes in the auxiliary gas flow ensure that the laser energy is not too large for a long time, causing ablation damage to the workpiece being processed, while effectively improving the processing efficiency of the laser cutting device 100.

[0110] It should be noted that the above embodiments all belong to the same inventive concept, and the descriptions of the embodiments have different focuses. For any details not described in individual embodiments, reference may be made to the descriptions in other embodiments. The above embodiments only express the implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of this invention shall be based on the attached claims.

Claims

1. A laser cutting device, characterized in that: The device comprises an auxiliary gas control unit, a laser generating unit and a gas self-excited oscillation unit, wherein the auxiliary gas control unit is connected to the side wall of the gas self-excited oscillation unit, and the focusing lens in the laser generating unit is embedded in the Helmholtz cavity of the gas self-excited oscillation unit; The auxiliary gas control unit is used to input the auxiliary gas into the Helmholtz cavity of the gas self-excited oscillation unit, and the auxiliary gas control unit includes a gas cylinder assembly, an air compressor assembly connected to the gas cylinder assembly, an electromagnetic throttle valve assembly connected to the air compressor assembly, and a control system electrically connected to the electromagnetic throttle valve assembly; the gas cylinder assembly is used to load the auxiliary gas, the air compressor assembly is used to compress the auxiliary gas, and the control system is used to adjust the flow rate of the auxiliary gas through the electromagnetic throttle valve assembly; The laser generating unit is used to focus the laser beam and pass it through the Helmholtz cavity of the gas self-excited oscillation unit, and the gas self-excited oscillation unit is used to make the auxiliary gas realize periodic changes in the gas flow rate in the Helmholtz cavity; the gas self-excited oscillation unit includes a Helmholtz upper nozzle and a Helmholtz lower nozzle, and the Helmholtz lower nozzle is threadedly connected to the Helmholtz upper nozzle; the Helmholtz upper nozzle is a hollow cylindrical structure, and the Helmholtz upper nozzle has no upper cylindrical surface; the Helmholtz lower nozzle is a cylindrical rotating body structure, and the lower cylindrical surface of the Helmholtz lower nozzle is provided with a second through hole; The focusing lens is embedded in the Helmholtz upper nozzle, and the diameter of the focusing lens is the same as the diameter of the Helmholtz upper nozzle; a third through hole is formed on the lower cylindrical surface of the Helmholtz upper nozzle, and the diameter of the second through hole is larger than the diameter of the third through hole; The length of the resonance cavity for achieving the best self-oscillation effect of the gas self-oscillation unit is L+L1-k, where L is the distance from the lower surface of the Helmholtz upper nozzle to the upper end of the collision wall of the Helmholtz lower nozzle. is the neck length of the Helmholtz lower nozzle, is the wall thickness of the lower end surface of the Helmholtz lower nozzle; Among them, the value of L satisfies Formula 1 to Formula 6: Formula 1: ; Formula 2: ; Formula 3: ; Formula 4: ; Formula 5: ; Formula 6: ; is the natural frequency of the Helmholtz cavity, is the local speed of sound, is the cross-sectional area of ​​the Helmholtz upper nozzle, is the volume of the Helmholtz cavity, is the neck length of the Helmholtz upper nozzle, is the Strouhal number, is the oscillation frequency, is the jet velocity; is the diameter of the Helmholtz cavity, d1 is the diameter of the third through hole, d2 is the diameter of the second through hole, is the jet diameter, and its size is equal; 、 、L1、 as well as Determined by the factory parameters of the Helmholtz chamber, U is calculated based on the preset flow of the electromagnetic throttle valve assembly and the preset air pressure of the air compressor assembly in combination with the gas Bernoulli equation.

2. The laser cutting device according to claim 1, characterized in that: The gas cylinder assembly includes a first gas cylinder for loading a first gas, a second gas cylinder for loading a second gas, and a third gas cylinder for loading a third gas; the air compressor assembly includes a first air compressor, a second air compressor, and a third air compressor; the electromagnetic throttle valve assembly includes a first electromagnetic throttle valve, a second electromagnetic throttle valve, and a third electromagnetic throttle valve; Among them, the inlet of the first air compressor is connected to the first gas cylinder, the outlet of the first air compressor is connected to the inlet of the first electromagnetic throttle valve, the inlet of the second air compressor is connected to the second gas cylinder, and the outlet of the second air compressor is connected to the inlet of the second electromagnetic throttle valve; the inlet of the third air compressor is connected to the third gas cylinder, and the outlet of the third air compressor is connected to the inlet of the third electromagnetic throttle valve; the outlet of the first electromagnetic throttle valve, the outlet of the second electromagnetic throttle valve and the outlet of the third electromagnetic throttle valve are all connected to the side wall of the gas self-excited oscillation unit.

3. The laser cutting device according to claim 2, characterized in that: Two bosses are symmetrically provided at the center of the cylindrical side surface of the Helmholtz upper nozzle, and each boss is provided with a first through hole; The outlet of the first electromagnetic throttle valve, the outlet of the second electromagnetic throttle valve, and the outlet of the third electromagnetic throttle valve are all connected to the first through hole.

4. The laser cutting device according to claim 2, characterized in that: The laser generating unit further includes a laser generator, the laser generator is used to emit a first laser beam to the focusing lens, and the focusing lens is used to focus the first laser beam into a second laser beam; The second laser beam passes through the third through hole and the second through hole in sequence.

5. The laser cutting device according to claim 2, characterized in that: The laser cutting device further comprises an air baffle unit threadedly connected to the Helmholtz lower nozzle, wherein the air baffle unit comprises an air baffle cover, the air baffle cover is a cylindrical structure, and the air baffle cover has no upper and lower end surfaces; The distance that the air shield extends beyond the lower end surface of the Helmholtz lower nozzle is smaller than the distance between the surface of the workpiece being processed and the lower end surface of the Helmholtz lower nozzle.

6. A laser cutting method, characterized in that: The laser cutting method is implemented by the laser cutting device according to any one of claims 1 to 5, and the method comprises: Connecting the circuit of the auxiliary gas control unit and adjusting the flow of the auxiliary gas through the electromagnetic throttle valve assembly so that the auxiliary gas flows into the Helmholtz upper nozzle according to a preset ratio; Turning on the circuit of the laser generating unit so that the laser generator generates a laser beam, the laser beam is focused by the focusing lens, and sequentially passes through the third through hole of the Helmholtz upper nozzle and the second through hole of the Helmholtz lower nozzle, ultimately making the high-energy light spot reach the surface of the workpiece being processed; Adjusting the resonant cavity length of the Helmholtz cavity to optimize the self-oscillation effect of the Helmholtz cavity; The distance that the air deflector hood exceeds the lower end surface of the Helmholtz lower nozzle is adjusted so that the actual effective length of the air deflector hood is smaller than the distance between the surface of the workpiece being processed and the lower end surface of the Helmholtz lower nozzle.

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