Novel light beam scanning device and method for laser welding and cleaning

Abstract

The invention discloses a novel light beam scanning device and method for laser welding and cleaning, and belongs to the technical field of laser welding and cleaning. The novel light beam scanning device comprises a cylindrical wedge-shaped mirror, the cylindrical wedge-shaped mirror is installed on a motor, and a reflecting mirror and a light beam shaping and isolating device are arranged at the front end of the cylindrical wedge-shaped mirror; a field lens is arranged at the rear end of the cylindrical wedge-shaped lens; the incident plane of the cylindrical wedge-shaped mirror is of a circular structure, the emergent plane of the cylindrical wedge-shaped mirror is composed of two different semicircular inclined planes, the center height of one semicircular inclined plane is not changed, the peripheral height of the semicircular inclined plane is gradually increased in the anticlockwise direction, the peripheral height of the other semicircular inclined plane is not changed, and the center height of the other semicircular inclined plane is gradually increased in the clockwise direction. According to the novel light beam scanning device and method provided by the invention, light beam scanning is realized based on the cylindrical wedge-shaped mirror, the clamping problem does not exist in the scanning process, the scanning is uniform, the motor does not need to be frequently reversed, and the requirement on the motor is low.

Description

Technical Field

[0001] The present invention relates to a beam scanning method. Specifically, it relates to a novel beam scanning device and method for laser welding and cleaning, belonging to the technical field of laser welding and cleaning. Background Art

[0002] Laser welding machines and laser cleaning machines are two new types of laser devices that are recently being rapidly industrialized. Laser welding can achieve welding of materials such as stainless steel, carbon steel, galvanized sheet, copper, and aluminum, and is mainly applied to fields such as thin-walled materials and precision parts. It can achieve spot welding, splicing welding, seal welding, overlay welding, etc., with small thermal deformation, beautiful and flat welds, high weld quality, and no need for secondary grinding treatment, etc.

[0003] Laser cleaning is mainly a new type of surface cleaning technology, which has the advantages of non-mechanical contact, no substrate damage, environmental friendliness, low operating cost, etc., and has broad application prospects in fields such as mold cleaning, electronic component preparation, cultural relic protection and restoration, paint removal and rust removal.

[0004] Both laser welding and laser cleaning work by using the high energy density of the laser, that is, a high-power focused laser beam is rapidly scanned, and the metal material or contaminants are irradiated, so as to achieve effects such as melting of the metal material or stripping of the contaminants. Therefore, the beam scanning method is one of the key technologies affecting the performance of laser welding machines and laser cleaning machines.

[0005] Currently, laser welding machines and laser cleaning machines mainly achieve beam scanning based on galvanometers. This method is commonly used in laser processing and marking systems. The specific method is to project a laser beam onto the galvanometer, and the reflected light spot is changed into a linear light spot by the rapid back-and-forth swing of the galvanometer. The galvanometer scanning method and device are already very mature and are also the most widely used, especially in the laser marking industry. However, galvanometer scanning also has its defects. This beam reciprocating scanning method requires the galvanometer motor to quickly change the rotation direction, that is, reverse direction, when moving to a certain point. The galvanometer commutation will bring the following problems: (1) High requirements for the performance of the motor and high cost; (2) Restricting the swing speed of the galvanometer; (3) The galvanometer pauses at the commutation point. This pause will inevitably lead to a longer laser irradiation time at this point. When used for laser cleaning, it is manifested as the cleaning degree at the edge of the scanning area being significantly higher than that in the middle area, that is, the cleaning is uneven, and this phenomenon is more obvious when the galvanometer scanning speed is lower. Sometimes, the substrate will be damaged at the edge of the scanning area. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a new beam scanning device and method for laser welding and cleaning in view of the above deficiencies of galvanometer-based beam scanning. The beam scanning is realized based on a cylindrical wedge mirror, and there is no jamming problem during the scanning process. It has the advantage of uniform scanning, and the motor does not need to frequently reverse, so the requirements for the motor are low.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions: A new beam scanning device for laser welding and cleaning, including a cylindrical wedge mirror, the cylindrical wedge mirror is installed on a motor, a reflector, a beam shaper and an isolator are arranged at the front end of the cylindrical wedge mirror, and a field lens is arranged at the rear end of the cylindrical wedge mirror; The incident surface of the cylindrical wedge mirror is a circular structure, and the exit surface of the cylindrical wedge mirror is composed of two different semi-circular inclined surfaces. The central height of one semi-circular inclined surface remains unchanged, and the peripheral height gradually increases in the counterclockwise direction. The peripheral height of the other semi-circular inclined surface remains unchanged, and the central height gradually increases in the clockwise direction.

[0008] An optimized scheme is that the inclination angles of the two semi-circular inclined surfaces are the same.

[0009] Further, the cylindrical wedge mirror and the motor are installed inside a housing, and the housing is an L-shaped structure.

[0010] Further, the reflector is installed at the corner of the L-shaped housing.

[0011] Further, the central axis of the cylindrical wedge mirror coincides with the rotating shaft of the motor.

[0012] Further, a switch is installed on the housing, and the switch is used to control the start and stop of the laser and the cylindrical wedge mirror.

[0013] A new beam scanning method for laser welding and cleaning includes the following steps: The motor drives the cylindrical wedge mirror to rotate unidirectionally, and then the laser starts to emit; The laser is transmitted by an optical fiber to the beam shaper and isolator and becomes an approximately parallel beam and then transmits in space; The beam is reflected by the reflector and then enters the circular incident surface of the cylindrical wedge mirror; The beam exits through the exit surface composed of two semi-circular inclined surfaces of the cylindrical wedge mirror; The transmitted beam is focused by the field lens to form a reciprocating swing scanning trajectory to realize laser welding or cleaning.

[0014] Further, the incident surface of the cylindrical wedge mirror is a circular structure, and the exit surface of the cylindrical wedge mirror consists of two different semi-circular inclined surfaces. The center height of one semi-circular inclined surface remains unchanged, and the peripheral height gradually increases in the counterclockwise direction. The peripheral height of the other semi-circular inclined surface remains unchanged, and the center height gradually increases in the clockwise direction.

[0015] After the present invention adopts the above technical solutions, compared with the prior art, it has the following advantages: The cylindrical wedge mirror in the present invention can achieve linear reciprocating scanning of the light beam by rotating unidirectionally driven by a motor. There is no commutation during the rotation of the cylindrical wedge mirror, and it is easy to achieve uniform rotation. The motor does not need to commutate frequently, and the requirements for the performance of the motor are relatively low.

[0016] Whether applied to laser cleaning or laser welding, it can achieve uniform irradiation of the surface of an object by the laser, without jamming problems, and has the advantage of uniform scanning, thereby improving the effect of laser cleaning or laser welding.

[0017] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0018] Figure 1 is a wedge plate of the structural schematic diagram; Figure 2 is a wedge plate side view of the transmission optical path; Figure 3 is a wedge plate and its schematic diagram of the principle of realizing beam scanning; Figure 4 is the structural schematic diagram of the cylindrical wedge mirror; Figure 5 is the schematic diagram of the principle of the cylindrical wedge mirror realizing beam scanning; Figure 6 is the structural schematic diagram of a beam scanning device (handheld part of a laser welding machine or cleaning machine) based on the cylindrical wedge mirror.

[0019] In the figure, 1 - cylindrical wedge mirror, 2 - housing, 3 - beam shaping and isolator, 4 - reflector, 5 - motor, 6 - field lens, 7 - focal point trajectory, 8 - switch. Detailed Embodiments

[0020] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0021] Embodiment 1 A novel beam scanning device for laser welding and cleaning As Figure 5 andFigure 6 As shown together, the present invention provides a novel beam scanning device for laser welding and cleaning, including a cylindrical wedge mirror 1. The incident surface of the cylindrical wedge mirror 1 is a circular structure, and the exit surface of the cylindrical wedge mirror 1 is composed of two different semi-circular inclined surfaces. The central height of one semi-circular inclined surface remains unchanged, and the peripheral height gradually increases in the counterclockwise direction. The peripheral height of the other semi-circular inclined surface remains unchanged, and the central height gradually increases in the clockwise direction.

[0022] The inclination angles of the two semi-circular inclined surfaces are the same.

[0023] The cylindrical wedge mirror 1 is installed on the motor 5 and is driven by the motor 5 to rotate. The cylindrical wedge mirror 1 and the motor 5 are installed inside the housing 2. The housing 2 is of an L-shaped structure.

[0024] A reflector 4, a beam shaper and isolator 3 are provided at the front end of the cylindrical wedge mirror 1. The reflector 4 is installed at the corner of the L-shaped housing 2.

[0025] A field lens 6 is provided at the rear end of the cylindrical wedge mirror 1.

[0026] The laser is transmitted by an optical fiber into the beam shaper and isolator 3 and becomes an approximately parallel beam and is transmitted in space. After being reflected by the reflector 4, it is incident into the cylindrical wedge mirror 1. The transmitted light is then focused by the field lens 6 to form a focal point trajectory 7, and a high-power density area for welding or cleaning is formed near the focal point trajectory 7.

[0027] A switch 8 is installed on the housing 2. The switch 8 is used to control the start and stop of the laser and the cylindrical wedge mirror 1. After pressing the switch 8, the cylindrical wedge mirror 1 starts to rotate driven by the motor 5, and then the laser starts to emit, thus realizing beam scanning.

[0028] The motor 5 in the present invention can be either a common motor or a hollow rotor motor.

[0029] When the cylindrical wedge mirror 1 is installed on a common motor, it is only necessary that the motor shaft coincides with the central axis of the cylindrical wedge mirror 1. However, the problem of the motor blocking light needs to be considered. Therefore, a motor with a smaller diameter is preferably selected under the condition that the rotational speed and torque meet the requirements, or the diameter of the cylindrical wedge mirror 1 can be made larger.

[0030] When the cylindrical wedge mirror 1 is installed on a hollow rotor motor, the cylindrical wedge mirror 1 is installed at the hollow position of the rotor, as Figure 6 shown, so that there will be no light blocking and the occupied space is small.

[0031] The specific working principle of the cylindrical wedge mirror 1: Suppose there is a wedge plate which is processed from a cuboid and the inclination angle , as Figure 1 shown. When a beam of laser is vertically incident on the wedge plate from the upper surface ABCD, as Figure 2 shown, assuming that the incident angle on the exit surface after passing through the wedge plate is , and the refraction angle is , then (1) In the formula, is the refractive index of the wedge plate, is the refractive index of air. Let , then (2) Obviously, the exit light deviates from the incident light direction, and the deviation angle is (3) From Figure 2 , it can be seen that the incident angle on the exit surface is equal to the tilt angle , then (4) It can be seen that the angle by which the laser deviates from the original incident direction after passing through the wedge plate is determined by the tilt angle of the wedge plate. Numerical simulation shows that the larger the tilt angle of the wedge plate, the larger the beam deviation angle . Assuming that the wedge plate material is quartz with a refractive index of , and the tilt angle of the wedge plate, then the beam deviation angle . For practical applications, the magnitude of this deviation angle is still relatively considerable and has good application value.

[0032] The above calculation assumes that the incident angle is 0, that is, the laser is vertically incident. If the incident angle is not 0 but equal to , then the deviation angle of the exit light is (5) Comparing equations (4) and (5), it can be seen that the incident angle has a certain influence on the deviation angle , but theoretical calculations show that this influence is relatively small within a certain range. Therefore, the following content will still take the incident angle as 0, that is, the beam is vertically incident, as an example to illustrate the present invention.

[0033] From the previous conclusion (see equation 4), the beam deviation angle is determined by the tilt angle Decision, that is to say, if the incident direction and position of the laser beam are kept unchanged, as long as the tilt angle of the wedge plate can be quickly changed the deviation angle of the outgoing light can be quickly changed , that is, by quickly changing the tilt angle beam scanning is achieved. For example, if the tilt angle changes rapidly within beam scanning within will be achieved quickly. Based on this method, the present invention designs a new beam scanning scheme.

[0034] First of all, the present invention provides a special wedge plate, as Figure 3 shown. This wedge plate is processed from a cuboid , but it is essentially different from the wedge plate Figure 1 given. Assume that the midpoints of the edges of the cuboid AB , 、 and CD are respectively , , , . After processing, the plane becomes the inclined plane , and the tilt angle ; the plane becomes , and the tilt angle . The tilt directions of the surfaces and are opposite, and the wedge plate is .

[0035] When the laser is vertically incident from the center point, it will vertically exit from the center point to form a transmitted beam . Obviously, the transmitted light does not deviate from the incident light. If the position of the incident laser is kept unchanged and the wedge plate is moved horizontally to the right, the incident light always remains stationary and vertically incident. However, the outgoing surface is inclined and the tilt angle gradually increases as the wedge plate moves to the right, increasing from 0 at the initial to at . Therefore, during the horizontal rightward movement of the wedge plate, the outgoing light will deviate from the incident light, and the deviation angle becomes larger and larger. When the leftmost side AD of the wedge plate reaches directly below the incident light, the deviation angle of the outgoing light reaches the maximum, and the outgoing beam is ; Thereafter, the wedge plate starts to turn and move leftward. At this time, the outgoing light will be from towards getting closer. When the incident point reaches O point, the outgoing light returns to position. At this time, the wedge plate continues to move leftward. Since the outgoing surface and the outgoing surface are inclined in opposite directions, the outgoing light begins to deviate from towards getting closer. When the wedge plate moves to the far right and BC reaches directly below the incident light, the deviation angle of the outgoing light reaches the maximum, and the outgoing light beam is . Thus, if the wedge plate moves back and forth left and right, the outgoing light will be reciprocally scanned between and .

[0036] As can be seen from the previous analysis, Figure 3 the wedge plate shown can achieve beam scanning. However, the wedge plate needs to move back and forth. Obviously, when the wedge plate changes direction, there will be a short pause, resulting in a longer irradiation time of the laser beam at the edge ( and vicinity). If it is used for laser cleaning, the cleaning effect of the edge part will be different from that of the middle part, which is similar to the case of a galvanometer.

[0037] To overcome the above disadvantages, the present invention has improved the Figure 3 cuboid special wedge plate and designed a cylindrical wedge mirror, as shown in Figure 4 . This cylindrical wedge mirror can be regarded as being deformed from the Figure 3 cuboid special wedge plate, that is, "rolling up" the wedge plate with as the axis, so that , and coincide, and coincide, forming a special cylindrical wedge mirror. The upper surface of this cylindrical wedge mirror is a circle, and the lower surface has a relatively special shape, consisting of two different semi-circular inclined surfaces ( and ). To better understand the shape of these two semi-circular inclined surfaces, the following description is made.

[0038] is the dividing line between the two semi-circular inclined surfaces on the lower surface, is parallel to the upper surface, and are in a plane. Suppose there is a certain line segment with its initial position at and coinciding with , that is, the two ends of the line segment are respectively at point, The points coincide. Now, with this line segment starting from and centered at , it rotates counterclockwise along the lower surface . Then, one end of this line segment always coincides with , maintaining the same vertical position. However, the other end of this line segment will gradually rise along the lower surface and coincide with point E after rotating 180°. To facilitate the understanding of the inclined plane , Figure 4 shows the postures of line segments 1, 2, and 3 at three positions on the inclined plane. Similarly, assume that a certain line segment starts from and rotates clockwise along the lower surface with as the axis. Then, one end of this line segment rises continuously along the central axis , while the other end will move along the semi - circle (the semi - circle is parallel to the semi - circle ). After rotating 180°, one end of the line segment coincides with , and the other end coincides with . To facilitate the understanding of the inclined plane , Figure 4 shows the postures of line segments 4, 5, and 6 at three positions on the inclined plane. Here, it is assumed that the inclined angles of the inclined plane and are equal, that is, .

[0039] Based on Figure 3 the cuboid - type wedge - plate structure and the principle of realizing beam scanning, it is not difficult to think that as long as the cylindrical wedge mirror in Figure 4 rotates unidirectionally, beam linear reciprocating scanning can be achieved, as shown in Figure 5 . When the laser beam is vertically incident on the upper surface of the cylindrical wedge mirror as shown in the figure, the rotation of the cylindrical wedge mirror driven by the motor can make the transmitted beam swing reciprocally.

[0040] Assume that the laser beam incident point is the mid - point of O , and its transmitted beam is . When the cylindrical wedge mirror rotates clockwise, the transmitted beam deviates from the incident light direction due to refraction. First, the transmitted beam deviates to the right. When the edge of the inclined plane is almost directly below the incident light, it can be considered that the angle at which the beam can swing to the right reaches the maximum, and its transmitted beam is . When the cylindrical wedge mirror rotates a little more, the edge of the inclined plane is Just below the direct path of the incident light, at this time the outgoing light deviates to the left and the deviation angle reaches the maximum value. The transmitted light beam here is . As the cylindrical wedge mirror rotates clockwise, the transmitted light beam begins to swing to the right and successively reaches , . That is, when the cylindrical wedge mirror rotates clockwise, the transmitted light beam swings back and forth according to the rule, thus realizing the reciprocating scanning of the light beam. It can be seen that the angular range of the light beam scanning is determined by the inclination angles and . The specific values need to be determined according to actual application requirements (such as laser welding, laser cleaning, etc.).

[0041] From the above analysis, it can be seen that the cylindrical wedge mirror can realize the reciprocating scanning of the light beam along a straight line by rotating unidirectionally driven by a motor. The key is that there is no commutation during the rotation of the cylindrical wedge mirror, which is easy to achieve uniform rotation and has relatively low requirements for the performance of the motor. Whether applied to laser cleaning or laser welding, it can realize the uniform irradiation of the surface of the object by the laser, thereby improving the effect of laser cleaning or laser welding.

[0042] Embodiment 2 A novel beam scanning method for laser welding and cleaning The present invention provides a novel beam scanning method for laser welding and cleaning, including: The motor drives the cylindrical wedge mirror to rotate unidirectionally, and then the laser starts to emit; The laser is transmitted by an optical fiber to a beam shaper and isolator and becomes an approximately parallel beam for spatial transmission; After the light beam is reflected by a mirror, it is incident on the circular incident surface of the cylindrical wedge mirror; The light beam is emitted through the exit surface composed of two semi-circular inclined surfaces of the cylindrical wedge mirror; The transmitted light beam is then focused by a field lens to form a reciprocating scanning trajectory to realize laser welding or cleaning.

[0043] In the present invention, the incident surface of the cylindrical wedge mirror is a circular structure. The exit surface of the cylindrical wedge mirror is composed of two different semi-circular inclined surfaces. The central height of one semi-circular inclined surface remains unchanged, and the peripheral height gradually increases in the counterclockwise direction. The peripheral height of the other semi-circular inclined surface remains unchanged, and the central height gradually increases in the clockwise direction.

[0044] The above is an example of the best implementation mode of the present invention. The parts not described in detail are all common general knowledge of those of ordinary skill in the art. The protection scope of the present invention is subject to the content of the claims. Any equivalent transformation based on the technical inspiration of the present invention is also within the protection scope of the present invention.

Claims

1. A novel beam scanning device for laser welding and cleaning, characterized in that, It includes a cylindrical wedge mirror (1), the cylindrical wedge mirror (1) is installed on a motor (5), a reflector (4), a beam shaper and isolator (3) are provided at the front end of the cylindrical wedge mirror (1), and a field lens (6) is provided at the rear end of the cylindrical wedge mirror (1); The incident surface of the cylindrical wedge mirror (1) is a circular structure, and the exit surface of the cylindrical wedge mirror (1) is composed of two different semi-circular inclined surfaces. The central height of one semi-circular inclined surface remains unchanged, and the peripheral height gradually increases in the counterclockwise direction. The peripheral height of the other semi-circular inclined surface remains unchanged, and the central height gradually increases in the clockwise direction.

2. The novel beam scanning device for laser welding and cleaning according to claim 1, wherein The inclination angles of the two semi-circular inclined surfaces are the same.

3. A novel beam scanning device for laser welding and cleaning as claimed in claim 1, characterized in that, The cylindrical wedge mirror (1) and the motor (5) are installed inside a housing (2), and the housing (2) is an L-shaped structure.

4. A novel beam scanning device for laser welding and cleaning according to claim 3, characterized in that, The reflector (4) is installed at the corner of the L-shaped housing (2).

5. A novel beam scanning device for laser welding and cleaning according to claim 1, characterized in that, The central axis of the cylindrical wedge mirror (1) coincides with the rotation axis of the motor (5).

6. The novel beam scanning device for laser welding and cleaning according to claim 3, characterized in that, A switch (8) is installed on the housing (2), and the switch (8) is used to control the start and stop of the laser and the cylindrical wedge mirror (1).

7. A novel beam scanning method for laser welding and cleaning, using a novel beam scanning device for laser welding and cleaning according to any one of claims 1 to 6, characterized in that, It includes the following steps: The motor drives the cylindrical wedge mirror to rotate unidirectionally, and then the laser starts to emit; The laser is transmitted by an optical fiber and becomes an approximately parallel beam in the beam shaper and isolator and then is transmitted in space; The beam is reflected by the reflector and then enters the circular incident surface of the cylindrical wedge mirror; The beam exits through the exit surface composed of two semi-circular inclined surfaces of the cylindrical wedge mirror; The transmitted beam is focused by the field lens to form a reciprocating swinging scanning trajectory to achieve laser welding or cleaning.

8. A novel beam scanning method for laser welding and cleaning as claimed in claim 7, characterized in that The incident surface of the cylindrical wedge mirror is a circular structure, and the exit surface of the cylindrical wedge mirror is composed of two different semi-circular inclined surfaces. The central height of one semi-circular inclined surface remains unchanged, and the peripheral height gradually increases in the counterclockwise direction. The peripheral height of the other semi-circular inclined surface remains unchanged, and the central height gradually increases in the clockwise direction.

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