CN110681992A - An adjustable broadband laser processing optical system and processing method - Google Patents

Abstract

The invention discloses an adjustable broadband laser processing optical system and a processing method, and belongs to the field of laser processing optical systems. The system comprises a laser, a movable focusing lens unit, a scanning galvanometer unit and a working surface; the movable focusing lens unit comprises a focusing lens, a first motor and a guide rail, wherein the first motor controls the focusing lens to move along the guide rail; the scanning galvanometer unit comprises a galvanometer and a second motor, and the galvanometer is connected with the second motor; the laser processing device comprises a laser, a focusing lens, a vibrating mirror, a laser device and a laser processing device, wherein the laser is used for processing a workpiece on a working surface, the laser device is used for emitting light beams to the focusing lens at a certain divergence angle, the light beams are collimated and focused by the focusing lens, then emitted to the vibrating mirror and reflected by the vibrating mirror, and therefore the laser processing device is used for processing the workpiece on. The invention can quickly and sensitively adjust the size of the working light spot, has obvious advantages especially for special-shaped or uneven processing surfaces, and also improves the processing uniformity and the processing efficiency.

Description

An adjustable broadband laser processing optical system and processing method

technical field

The invention belongs to the field of laser processing optical systems, and more particularly, relates to an adjustable broadband laser processing optical system and method.

Background technique

Laser processing technology is a surface modification technology that uses high-energy lasers and nanomaterials to strengthen alloys for various parts. Engineering properties such as oxidation. With the rapid development of industrialization and laser technology industry in recent years, laser processing has been widely used in direct molding and remanufacturing production processes as an effective method to improve the surface quality and service life of devices.

The existing laser processing and forming systems mostly use optical elements to cut, shape and reorganize the laser beam. The function of the laser processing optical system is to convert the laser beam emitted by the laser and project it on the processing surface for laser cladding processing. The existing laser processing optical system is difficult to meet the processing efficiency and quality requirements, and its fixed working mode usually cannot be flexibly changed into spots. low efficiency. Moreover, the efficiency and quality of cladding in traditional processing systems are limited. Taking the integrator mirror cladding system as an example, it uses the scalar diffraction theory to redistribute and then converge the beam. The light field distribution transformed by the integrator mirror has strong interference. Diffraction effect, in a short working time, the spot fringe structure is obvious, which destroys the uniformity of the beam; although the fringe structure will gradually weaken with the increase of the laser irradiation time due to the existence of thermal diffusion, but due to the high-speed scanning process of the laser , its working temperature field still cannot guarantee uniformity, which will affect the efficiency and quality of cladding. Therefore, the development of a tunable broadband laser processing optical system is of great significance for laser processing applications.

SUMMARY OF THE INVENTION

Aiming at the defects of the prior art, the present invention proposes an adjustable broadband laser processing optical system and a processing method, aiming at solving the problems of poor processing quality and low efficiency of the existing laser processing system.

In order to achieve the above object, the present invention provides an adjustable broadband laser processing optical system, the system includes a laser, a moving focusing lens unit, a scanning galvanometer unit and a working surface; the moving focusing lens unit includes a focusing lens, a first a motor and a guide rail, the first motor controls the focusing lens to move along the guide rail; the scanning galvanometer unit includes a galvanometer mirror and a second motor, the galvanometer mirror is connected to the second motor; the laser The emitted light beam is incident on the focusing lens at a certain divergence angle, the beam is collimated and focused by the focusing lens and then incident on the galvanometer mirror, and then reflected by the galvanometer mirror, so as to be used for the workpiece on the working surface. Laser processing is performed. The invention uses a collimating and focusing combined mirror, which does not need to be collimated and then focused, reduces lens pollution, saves processing cost, and reduces operation difficulty.

Further, the system further includes a beam splitting device, the beam splitting device includes a beam splitting prism, two symmetrically placed mirrors and a sliding groove, the beam splitting prism can move along the sliding groove;

The light beam is reflected by the galvanometer to the two beam-splitting prism surfaces of the beam-splitting prism, and is reflected and split into two sub-beams by the beam-splitting prism, and the two sub-beams are respectively reflected by the mirror and converge on the working surface Get two spots.

Further, the two sub-beams form a specific angle when they converge, and a multi-channel powder feeding tube is placed in the hollow non-light area formed between the two sub-beams to carry out synchronous transmission of light powder.

Further, the focusing lens is connected to the bracket on the guide rail, and is controlled by the first motor to move back and forth along the optical axis direction on the guide rail to adjust the spot width during scanning. By moving the position of the focusing lens, the width of the light spot on the working surface can be quickly adjusted, which improves the processing flexibility and processing efficiency of the equipment.

Further, the second motor drives the galvanometer to vibrate back and forth to perform broadband beam scanning, and the scanning angle of the galvanometer is adjusted by programming, and the scanning range of the light spot is adjusted to realize efficient processing of parts of different sizes.

The present invention also provides a processing method based on the aforementioned broadband laser processing optical system, by adjusting the scanning speed of the galvanometer to control the dwell time of the light spot at each position, so as to obtain a light field distribution of a specific shape.

Further, the scanning speed of the galvanometer when the deflection angle is large is controlled to be less than the scanning speed when the deflection angle is small, and the light field distribution on the working surface presents a saddle-shaped light field with high sides and a low center, thereby A uniformly distributed temperature field is obtained, which improves the processing quality of the cladding layer.

Further, by controlling the beam splitting prism to move back and forth between the two mirrors along the sliding groove, the energy distribution of the two sub-beams is adjusted, thereby changing the width ratio of the two light spots on the working surface.

Further, the converging angle of the two sub-beams is changed by adjusting the rotation angle of the reflecting mirror, so as to control the distance between the two light spots on the working surface.

The present invention has the following beneficial effects:

(1) The present invention changes the scanning range of the light spot by controlling the angle of the galvanometer, and realizes the spot change in combination with the moving adjustment of the focusing lens, which improves the flexibility of processing and realizes the efficient processing of workpieces of various sizes.

(2) The present invention utilizes the spectroscopic device to realize laser cladding with hollow beam and inner powder feeding on the one hand, which improves the coupling utilization rate of the optical powder; efficiency.

(3) The present invention controls the deflection of the galvanometer by programming, and can realize saddle-shaped, parabolic and other special light field distributions according to actual needs, so as to realize the processing of special-shaped surfaces; especially, the saddle-shaped light field can obtain evenly distributed scanning The temperature field improves the processing quality of the cladding layer.

Description of drawings

Fig. 1 is the schematic diagram of the embodiment of the adjustable broadband laser processing optical system of the present invention;

2 is a schematic diagram of another embodiment of the adjustable broadband laser processing optical system of the present invention;

Fig. 3 is a schematic diagram of the principle of moving spot changing of the collimating focusing mirror;

Fig. 4 is the schematic diagram that the beam splitting prism moves to adjust the energy ratio of two light spots;

Figure 5(a) is a schematic diagram of changing the angle of the mirror to control the center spacing of the double light spots;

Figure 5(b) is a schematic diagram of the corresponding light spot distribution when the angle of the mirror is changed to adjust the center distance of the double light spots;

Fig. 6(a) is a schematic diagram showing the dwell time, light intensity distribution and temperature field distribution of the saddle-shaped distribution spot;

Figure 6(b) is a schematic diagram of the scanning spot distribution in one scanning period corresponding to the saddle-shaped distribution;

FIG. 7 is a schematic diagram of the powder feeding tube built in the spectroscopic device to realize the powder feeding in the light.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Example 1

As shown in FIG. 1 , an adjustable broadband laser processing optical system provided by an embodiment of the present invention includes a fiber laser 1 , a focusing lens 2 , a first motor and a guide rail 3 for controlling the movement of the focusing lens 2 , and a galvanometer 4 , the second motor 5 and the working surface 6 that drive the galvanometer to vibrate. The light beam emitted by the fiber laser 1 is incident on the focusing lens 2 at a certain divergence angle.

The focusing lens 2 is connected with the bracket on the guide rail, and is controlled by the first motor to move back and forth along the optical axis direction on the guide rail, so as to achieve the effect of 6 spots on the working surface. The traditional laser processing optical system uses a combination of multiple focusing mirrors to move and adjust the spot change, while the present invention uses a collimated focus combination mirror, which can achieve very convenient long-distance focusing, reduce lens pollution, and has a fast adjustment speed, which is conducive to real-time spot change. deal with.

The galvanometer 4 is connected with the second motor 5, and the back and forth vibration of the galvanometer 4 is controlled by the second motor 5, so as to realize the process of broadband beam scanning. In special occasions such as the surface of large shaft parts, the length of the rectangular light spot can be freely adjusted by galvanometer scanning (as shown in the y direction in the figure). In addition, the repeated irradiation by scanning is beneficial to the vibration of the laser molten pool, improving the molten pool, improving the cladding quality, and deepening the hardening depth of laser cladding or laser strengthening.

Example 2

As shown in FIG. 2, another adjustable broadband laser processing optical system provided by the embodiment of the present invention includes a fiber laser 1, a focusing lens 2, a first motor and a guide rail 3 for controlling the movement of the focusing lens 2, a galvanometer 4, The second motor 5 that drives the vibration of the galvanometer, the beam splitting prism 7, the reflecting mirror 8, the sliding groove 9 and the working surface 6 for controlling the position of the beam splitting prism 7, wherein the beam splitting prism 7, the reflecting mirror 8 are used to control the position of the beam splitting prism 7 The sliding groove 9 constitutes a spectroscopic device. The beam emitted by the fiber laser 1 is incident on the focusing lens 2 at a certain divergence angle. The beam is collimated and focused by the focusing lens 2 and then incident on the galvanometer mirror 4, and is reflected by the galvanometer 4 to the two beam splitting prisms of the beam splitting prism 7. The beam is collected by the beam splitting prism. 7 After the reflection and splitting, it is reflected by two symmetrically placed mirrors 8 and converges on the working surface 6 . The dichroic prism 7 can move back and forth on the sliding groove 9, and is limited by pins.

The focusing lens 2 is connected with the bracket on the guide rail, and is controlled by the first motor to move back and forth along the optical axis direction on the guide rail, so as to achieve the effect of 6 spots on the working surface. When the galvanometer 4 is polarized to the dotted line position, the light beam changes from a solid line to a dotted line, and the light spot scans back and forth on the working surface 6 along the y direction shown in the figure within a certain range, forming a double rectangular light spot of a certain length.

Fig. 3 shows that when the focusing lens 2 moves to the dashed line position on the guide rail 3, the solid line of the system becomes as shown by the dashed line, realizing the function of changing the double-rectangular spot width (x direction in the figure) on the working surface 6. The second motor 5 controls the vibration angle of the galvanometer 4 by programming, and can adjust the scanning range of the reflected light spot on the working surface, so as to realize the change of the length of the scanning double light spot in the scanning direction (the y direction in the figure). The width of the light spot can be adjusted by moving, and the function of adjustable rectangular double light spot can be realized.

As shown in FIG. 4 , when the beam splitting prism 7 moves from the solid line center position to the dotted line position along the sliding groove 9, the energy ratio of the two beam splitting beams is different, and the vibration range of the galvanometer 4 is from the solid line to the dotted line position. of double rectangular spots.

As shown in Fig. 5(a), when the mirror 8 is rotated from the solid line position to the dashed line position, the two beams change from the solid line to the dashed line, and the change of the spot distribution of the working surface is shown in Fig. 5(b). The change of the convergence angle can realize the change of the double spot spacing on the working surface.

By programming the deflection of the galvanometer, special light field distributions such as saddle and parabola can be realized according to actual needs, so as to realize the processing of special-shaped surfaces. For example, in this embodiment, the saddle-shaped light field distribution is obtained by adjusting the scanning speed of the galvanometer to control the dwell time of the light spot at each position. Figure 6(a) shows the light spot staying time t, light field intensity distribution I and temperature field distribution T in the processing process, and Figure 6(b) shows the saddle-shaped light field formed to scan the light spot in one scanning period distribution. When the deflection angle of the galvanometer is large, the scanning speed is small, and when the deflection angle is small, the scanning speed is large, so that the light field distribution on the working surface presents a saddle-shaped light field with high sides and low center. It can be seen from Fig. 6(b) that the cladding temperature field corresponding to the saddle-shaped light field is approximately a rectangular distribution, which makes the thermal action process formed by the cladding layer uniform, and overcomes the defect of the crescent-shaped distribution of the conventional hardened layer. Hardened deposits of uniform thickness, significantly improving processing quality. For another example, when the deflection angle of the galvanometer is large, the scanning speed is large, and when the deflection angle is small, the scanning speed is small, so that the light field distribution on the working surface presents a parabolic light field with low sides and high center. Machining of locally convex surfaces. It can be seen that by programming the scanning speed under the deflection angle of the galvanometer, the light field distribution of any specific shape can be obtained, and the processing of the special-shaped surface can be realized.

On the basis of the above explanation of the composition of the laser processing optical system, Figure 7 shows a schematic diagram of the powder feeding tube built in the spectroscopic device to achieve optical powder feeding. The beam splitting prism 7 and a pair of reflecting mirrors 8 make the two photon beams converge on the working surface 6 at a certain inclination angle, and the multi-channel powder feeding tube 10 is placed in the hollow non-light area formed between the two photon beams to realize the internal transmission of light. The powder and the light powder are transported synchronously, and the hollow beam device provides space for the powder feeding within the light, thus realizing the efficient combination and utilization of the light powder, thereby greatly improving the processing quality of the cladding layer. Moreover, adding a spectroscopic device realizes the simultaneous processing of double light spots, which effectively improves the processing efficiency.

In addition, the present invention can also be directly combined with a fiber laser with a QBH connector and an industrial robot to improve the processing efficiency of the laser processing system.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (10)

1. An adjustable broadband laser processing optical system is characterized by comprising a laser, a movable focusing lens unit, a scanning galvanometer unit and a working surface;

the movable focusing lens unit comprises a focusing lens, a first motor and a guide rail, wherein the first motor controls the focusing lens to move along the guide rail;

the scanning galvanometer unit comprises a galvanometer and a second motor, and the galvanometer is connected with the second motor;

the laser processing device comprises a laser, a focusing lens, a vibrating mirror, a laser device and a laser processing device, wherein the laser is used for processing a workpiece on a working surface, the laser device is used for emitting light beams to the focusing lens at a certain divergence angle, the light beams are collimated and focused by the focusing lens, then emitted to the vibrating mirror and reflected by the vibrating mirror, and therefore the laser processing device is used for processing the workpiece on.

2. The broadband laser machining optical system according to claim 1, further comprising a beam splitting device including a beam splitting prism, two symmetrically disposed mirrors, and a sliding groove, the beam splitting prism being movable along the sliding groove;

the light beam is reflected to two light splitting prism surfaces of the light splitting prism through the vibrating mirror, the light is split into two sub-light beams through the light splitting prism, and the two sub-light beams are respectively reflected by the reflecting mirror and then converged on the working surface to obtain two light spots.

3. The broadband laser processing optical system of claim 2, wherein the two sub-beams form a specific angle when converging, and a multi-channel powder feeding tube is disposed in a hollow no-light area formed between the two sub-beams for synchronous light powder delivery.

4. The broadband laser processing optical system according to any one of claims 1 to 3, wherein the focusing lens is connected to a holder on a guide rail, and is controlled by the first motor to move back and forth on the guide rail in the optical axis direction to adjust the spot width during scanning.

5. The broadband laser processing optical system according to any one of claims 1 to 3, wherein the second motor drives the galvanometer to oscillate back and forth for broadband beam scanning, and the scanning range of the light spot is adjusted by programming and adjusting the scanning angle of the galvanometer.

6. A processing method based on the broadband laser processing optical system of any one of claims 1 to 3, characterized in that the stay time of each position light spot is controlled by adjusting the scanning speed of the galvanometer to obtain a light field distribution with a specific shape.

7. The process of claim 6, wherein the scanning speed of the galvanometer at a larger deflection angle is controlled to be lower than that at a smaller deflection angle, so as to obtain a saddle-shaped light field with a light field distribution presenting high sides and low center on the working surface.

8. The machining method of the broadband laser machining optical system according to claim 2 or 3, wherein the width ratio of the two light spots on the working surface is changed by controlling the beam splitting prism to move back and forth between the two reflecting mirrors along the sliding groove to adjust the energy distribution of the two sub-beams.

9. A processing method based on the broadband laser processing optical system of claim 2 or 3, wherein the distance between the two light spots on the working surface is controlled by changing the convergence angle of the two sub-beams by adjusting the rotation angle of the reflecting mirror.

10. A laser processing apparatus using the broadband laser processing optical system according to any one of claims 1 to 5.

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