Method for correcting path deviation during laser pointing change, and apparatus and machine tool

Abstract

To provide a method for correcting a path deviation during laser pointing change.SOLUTION: When laser (110) emitted from a laser emitter (100) changes a pointing direction according to the rotation of a rotary stage (400), the laser which is reflected and changes a propagation direction continues to propagate towards a diaphragm, so that a laser beam passing through the diaphragm continues to propagate along a preset path. Also provided are a processing device using the method, an apparatus, and a machining device. According to the method, a light beam propagation direction deviating from a preset direction caused by factors such as rotation of the rotary stage, stress, vibration, elastic deformation or temperature can be eliminated, so that the pointing of the laser to a workpiece conforms to the preset direction, and a light spot shape acting on the workpiece also keeps stable, so as to meet the requirement for precision machining.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for adjusting the optical path of a laser, and more particularly to a method for compensating for deviations from a preset propagation direction and / or position of a rotating and propagating laser, and to an apparatus and machine tool using the method. [Background technology]

[0002] Lasers are currently widely used in cutting, welding, and marking processes for metal sheet metal and profile materials, as well as in other technical fields such as ultrahard material processing for manufacturing cutting tools. Cutting or welding sheet metal and profile materials using lasers with multi-axis processing centers or articulated robots is the most common solution. The required processing operation is achieved by using machine axes to move the focused beam emitted from the laser oscillator (i.e., the laser output component used to perform the processing; commonly known in the industry as a cutting laser head or welding laser head, depending on its function) relative to the workpiece to be cut or welded. Alignment (also referred to as height adjustment) of the laser and the workpiece plane is achieved by an alignment module integrated into the laser device or the Z-axis of the multi-axis processing center. The laser oscillator is generally directly connected to the optical output terminal of the laser generator via a dedicated industrial interface (such as a QBH) and is an important functional component that highly integrates external optical path functions such as collimation, beam expansion, focusing, and convergence. The direct connection between the modularized laser oscillator and the optical output terminal of the laser generator not only simplifies the equipment assembly and improves the system reliability, but more importantly, it simplifies the mechanical operating structure and optical path structure, and the angle of the focused beam can be directly changed by the rotation and pitching motion of the laser oscillator, achieving a relatively large degree of freedom in processing. In addition, the highly integrated optical output terminal and laser oscillator minimize the free space optical path, minimizing the adverse effect of external disturbances on the beam pointing accuracy, contributing to improved processing accuracy.Although this type of solution can realize a wide range of free changes in the laser focus direction, it greatly amplifies the positioning error of the focused light spot due to the deviation of the radius of the laser rotation on the rotary stage. Furthermore, this type of solution requires that the optical output terminal of the laser generator be able to move freely in free space along with the laser oscillator. Therefore, this technical solution can only be used with optical fiber-coupled lasers in which the laser oscillator and the optical output terminal are connected using an optical fiber that has the properties of being able to be bent and stretched, or with optical fiber pulsed laser light sources at the microsecond or nanosecond level. However, this technical solution cannot be used with laser light sources such as optical fiber ultrafast laser generators whose optical fiber cannot be bent and stretched freely, or semiconductor laser generators that do not transmit light via optical fiber.

[0003] To allow for a wide range of laser focus direction changes and minimize rotational positioning errors, devices with eccentric oscillation structures are used in multi-axis processing centers for multi-axis laser processing with an XA and YZB axis system. This solution allows for a relatively small rotation radius and significantly reduces the rotational positioning error of the focused light spot. While this is possible with conventional pulsed lasers, ultrafast lasers are limited by technical constraints, such as the insufficient mobility characteristics of their optical fibers (the allowable bending radius is too large and the maximum optical fiber length is too short), making it impossible to install them in an oscillation mechanism. This makes it difficult to integrate ultrafast lasers into five-axis processing centers. To solve this problem, technical proposals have been put forward for a flight optical path in which part of the beam passes through the center of a rotary stage and is then emitted by a reflector placed at the center of the rotary stage (e.g., CN202020298469.9 and CN202020298514.0). In this series of proposals, after the laser beam is adjusted, it becomes coaxial with the rotation axis of the rotary stage. Therefore, no matter how the optical path part of the rotary stage rotates on the rotary stage, the beam always enters the same point on the reflector located on the rotation axis of the rotary stage in the same direction, and the angle between the laser beam emitted from the rotary stage and the rotation center axis of the rotary stage is constant. However, if the adjustment cannot be made accurately, or if the laser beam and the center of the rotating stage cannot maintain a coaxial position due to factors such as various stresses, vibrations, elastic deformation, and temperature that occur during operation of the processing center, the laser beam emitted through the reflector at the center of the rotating stage will experience angular deviation and positional shift (the latter is called "deviation") as the rotating stage rotates, ultimately causing a deviation in the laser spot acting on the workpiece, reducing processing accuracy and making it impossible to meet the requirements for precision processing.

[0004] On the other hand, using optical devices such as galvanometers instead of mechanical axes to change the beam focal direction is also a common solution. This technology usually does not require special requirements for the laser source, and technical improvements such as front-focus galvanometers have also been proposed. However, the focal beam can generally only be adjusted within a limited angle, making it difficult to meet the wide-ranging requirements for changing the laser focal direction in industrial applications. Another obvious problem is the limited focal length. In galvanometer processing, whether front-focus or rear-focus galvanometers, a focusing lens (field lens) with a larger diameter and longer focal length (i.e., working distance) is required to achieve a larger processing width. Larger diameter focusing lenses (field lenses) are not only difficult and costly to manufacture, but also reduce the laser pointing accuracy due to the long working distance, which reduces the processing positioning accuracy of the entire processing system. Therefore, using galvanometers to achieve large-scale, large-angle, and high-precision laser-free processing is often prohibitively expensive and difficult to implement.

[0005] On the other hand, using a multi-axis mechanical structure to change the angle of the workpiece is the most common solution in laser precision machining. This solution generally involves fixing the laser so that it is irradiating vertically downward, placing the workpiece on a rotary and oscillating stage, and controlling the pitching and rotational movements of the workpiece to adjust the direction of the laser's impact on the workpiece, i.e., changing the laser's focal direction. This method achieves the highest beam pointing accuracy without substantially changing the laser's optical path, and also offers advantages such as the placement of optical devices such as galvanometers and shortening the optical path, further expanding machining flexibility. Therefore, this solution is currently most widely used in high-precision machining fields such as laser machining of ultra-hard materials. However, this solution is limited by the installation of the multi-axis mechanical structure and is not versatile. Especially when used to machine long-axis parts, the part's rotation radius is amplified by the part's length, resulting in increased rotational positioning errors.

[0006] Therefore, in general, although engineers have developed many technical means for high-precision, large-angle laser processing, the problem of how to combine greater beam pointing freedom and better beam pointing positioning accuracy in current laser processing is still to be solved. Summary of the Invention [Problem to be solved by the invention]

[0007] One objective of the present invention is to provide a method for correcting path deviation during laser pointing change, which can eliminate deviations caused by factors such as stress, vibration, elastic deformation, and temperature during ultrafast laser path rotation and meet the requirements of precision machining.

[0008] Another object of the present invention is to provide a method for correcting path deviation when the laser pointing is changed, so that the laser pointing to the workpiece can be preset and kept stable when the rotary stage rotates to change the laser pointing, and meets the requirements for precision machining.

[0009] Another object of the present invention is to provide a method for correcting path deviation when the laser pointing is changed, so that the shape of the laser light spot acting on the workpiece can be kept stable when the rotary stage rotates and the laser pointing is changed, thereby meeting the requirements of precision machining.

[0010] Another object of the present invention is to provide a device for correcting path deviation when laser pointing changes, which corrects laser deviation so that even if the laser pointing direction changes by more than 30°, the laser pointing to the workpiece still conforms to the preset, and the shape of the light spot acting on the workpiece remains stable, thereby meeting the requirements of precision machining.

[0011] The fifth object of the present invention is to provide a multi-axis machine tool having a multi-axis machining sensor, in particular a device for correcting path deviation when the laser pointing changes, which satisfies the requirements for precision machining, improves machining accuracy, and effectively suppresses cost increases, particularly to solve the problem of reduced machining accuracy due to the excessively large rotation radius of the long axis system parts themselves. [Means for solving the problem]

[0012] As commonly understood, a laser is light emitted by atoms stimulated to do so. When electrons in atoms absorb energy, jump from a lower energy level to a higher energy level, and then return from the higher energy level to the lower energy level, the released energy is released in the form of photons. Laser types can be divided into continuous lasers and pulsed lasers. Lasers can be divided into hot lasers and cold lasers according to their pulse width characteristics.

[0013] The laser oscillator may be a nanosecond, femtosecond, or picosecond laser, and may generate laser light such as, but not limited to, infrared, blue light, green light, violet light, or extreme violet light.

[0014] An ultrafast laser is a pulsed laser whose output laser pulse width is several tens of nanoseconds or less, i.e., picosecond level or less. Core components involved in ultrafast lasers include an oscillator, a stretcher, an amplifier, a compressor, and the like.

[0015] In machining, the so-called workpiece is usually the material or semi-finished product used to manufacture a part or component, and is the object to be processed during the machining process, i.e., after machining the workpiece, a product that meets the processing or design requirements is obtained.

[0016] Precision machining is a processing technology that achieves extremely high levels of processing accuracy and surface quality. For example, in tool processing, size, straightness, contour, surface roughness, arc radius of cutting edge, processing accuracy, etc. all exceed the micron level.

[0017] The shaft work has a length that is three or more times its diameter.

[0018] A machining device (or machining center) is a machining device with multiple axes of motion: in a right-handed Cartesian coordinate system, there are X, Y and Z axes along which linear motion occurs, and A, B and C axes which rotate about the X, Y and Z axes, respectively.

[0019] Machining devices such as CNC machine tools are usually equipped with various control software, which transmits and receives commands in coded form to automatically machine workpieces.

[0020] In this invention, the laser beam emitted from the ultrafast laser first enters a part of the cavity, then exits the cavity and enters the laser projection relay member, which changes the laser's optical path and emits the laser, and finally is received by the light emission member and emitted to process the workpiece. The laser beam propagates within the cavity and propagates along a straight line at the exit end of the cavity, and the laser beam emitted from the light emission member is focused within the range of the rotation axis, that is, the laser beam focused light spot enters a cylindrical space with a radius of 100 mm centered on the rotation axis.

[0021] In the present invention, the cavity is mounted on a rotary stage and has an axis coaxial with the rotary stage rotation axis. The laser is incident on the cavity and propagates forward along a straight line, but is preset to propagate forward along the extension direction of the rotary stage rotation axis (including parallel or coaxial). The laser projection relay member is mounted on the rotary stage and rotates as driven by the rotary stage. The first reflector also rotates with the rotation of the rotary stage, changing the direction of the laser reflected by the first reflector. For example, when the laser is incident on the laser projection relay member and emitted, the direction of the laser rotates by 30° or more.

[0022] To meet the requirements of precision machining, the laser must propagate forward along a straight line while maintaining an intersection angle of 0 to 5° with the rotation axis (e.g., the rotation axis of a rotation stage) at a 0° to 5° angle, most preferably parallel or coaxial. Therefore, the propagation path of the laser beam entering the relay component after emission is also predetermined.

[0023] The laser projection relay reflects the laser at least once to change the beam direction of the laser.

[0024] The light output element includes at least one of a field lens, a galvanometer, a focusing lens, a beam expander, and a reflector, which may be commercially available or obtained from a conventional laser.

[0025] Aperture refers to the element that limits the beam in an optical system. It can be the edge of a lens, a frame, or a mounted perforated screen. Its main function is to limit the beam or the size of the field of view (image area). The aperture that most limits the beam in an optical system is called the aperture stop, and the aperture that most limits the field of view (size) is called the field stop. In the laser field, apertures are generally used to pre-adjust the optical path or as part of a spatial filter to shape the beam.

[0026] The laser beam path before entering the galvanometer has a set distance and a set angle with respect to the rotation axis of the rotary stage. If, due to factors such as stress, vibration, elastic deformation, temperature, and rotation error, the actual distance and actual angle between the laser beam path entering the galvanometer and the center line of the rotation axis of the rotary stage deviate too greatly from the set distance and set angle, the rotation of the rotary stage will result in an excessive laser positioning error, i.e., a positional deviation.

[0027] Under actual operating conditions, due to factors such as stress, vibration, elastic deformation, temperature, and rotation error, the laser passing through the rotary stage during rotation cannot maintain the original angle and distance (e.g., coaxial) with the rotary stage rotation axis, causing deflection and deviation in the laser propagation. After the deviated laser changes direction through the laser projection relay member, the deviation from the preset laser propagation path further increases.

[0028] When the method of the present invention is carried out, the rotation axis is the A-axis, B-axis, or C-axis, and the laser emitted by the light emitting element is distributed in the direction of rotation around the rotation axis (rotary stage), so that the laser light path is positioned at a specified angle by the rotational movement to perform machining.

[0029] When the method of the present invention is carried out, the rotary stage, the laser projection relay member and the light emission member mounted on the rotary stage move synchronously along a linear axis, and the laser distributed in the direction of rotation around the rotary axis moves synchronously along a straight line based on a command to perform machining of the workpiece.

[0030] The method of the present invention involves installing an aperture on the laser propagation path, specifically, in a portion of the propagation path after the laser exits the cavity and before it enters the light-emitting element, where the laser is reflected at least once and is acted upon by the aperture before it enters the light-emitting element, so that the aperture blocks the deviated laser beam and allows the non-deviated laser beam to continue propagation, thereby adapting the laser speed to the preset propagation path.

[0031] The method of the present invention can also compensate for the laser beam path before it enters the galvanometer. After compensation, the laser beam path before it enters the galvanometer has a second distance and a second angle with respect to the center line of the rotation axis of the rotary stage. The second distance is compared with the set distance, and the difference is 1 μm or less. The second angle is compared with the set angle, and the difference is 0.05 mrad or less. If this difference is 0.05 mrad or less, the relative position of the laser beam path entering the galvanometer and the center line of the rotation axis of the rotary stage (after compensation) is maintained.

[0032] In order to carry out the method of the present invention, it is preferable to select a cavity in which the laser beam emitted from the laser oscillator propagates in a straight line from one end of the cavity to the other end without being deflected. A cavity having a straight space can be adopted, such as, but not limited to, a tubular, conical, or truncated conical hole or cavity.

[0033] The method for correcting the path deviation when the laser pointing direction changes is to make the laser whose propagation direction has changed due to reflection continue to propagate toward the aperture, and make the laser beam that has passed through the aperture continue to propagate along the preset path when the laser changes its pointing direction as the rotary stage rotates.

[0034] When an optical device such as a galvanometer needs to be connected, it is usually necessary to reflect the beam again after passing through the aperture in order to adjust the direction of the laser incident on the galvanometer.

[0035] Another method for correcting path deviation when the laser pointing direction changes is to, when the laser changes direction as the rotary stage rotates, continue the laser whose propagation direction has been changed by reflection toward the aperture, and continue the laser beam that has passed through the aperture along the preset path, where it is reflected again and changes its propagation direction.

[0036] As the rotary stage rotates, the laser first emerges from the cavity of the rotating rotary stage, undergoes at least one reflection to change its propagation direction, and then continues to propagate toward the aperture, thereby allowing the laser beam that has passed through the aperture to continue propagating along a preset path.

[0037] The laser corrected by the method of the present invention not only allows the beam after passing through the aperture to propagate along a preset path, but also maintains the set distance and set angle between the laser optical path incident on the galvanometer and the rotation axis of the rotary stage at any angle of the rotary stage, allowing the laser to be directed toward the workpiece in accordance with the preset requirements, and the shape of the light spot acting on the workpiece remains stable, meeting the requirements for precision machining.

[0038] To ensure that the laser beam's pointing toward the workpiece meets the preset requirements and improve the stability of the light spot shape acting on the workpiece, a pre-correction is performed before the laser beam is incident on the cavity, so that the laser beam propagates forward along the direction of the rotation axis of the rotary stage (including parallel or coaxial). That is, the laser beam is first adjusted to be as coaxial or parallel as possible to the rotation axis of the rotary stage. Alternatively, a closed-loop pointing control is performed, that is, real-time closed-loop adjustment of the laser beam's pointing toward the workpiece is performed via a high-speed reflecting mirror and a sensor before the beam passes through the aperture.

[0039] A sensor is used to detect laser incident information, including the incident angle of the laser when it contacts the sensor element and the position of the laser on the sensor element. Typically, the position information is a two-dimensional coordinate system in which the laser's light spot is located on the sensor element. Although the laser beam has a set position on the sensor, factors such as stress, vibration, elastic deformation, temperature, and rotation error can cause the actual position of the laser beam on the sensor to deviate from the set position. After detecting the incident laser, the sensor obtains the position information, which determines the actual position and provides a basis for determining whether any deviation from the set position occurs and whether compensation is required. A sensor typically has at least one sensor element, but using two or more sensor elements is a better option to obtain more laser incident information.

[0040] The setting position information should be understood as information that is set after debugging and can meet the requirements of precision machining. For example, the distance between the focused light spot of the laser beam and the rotation axis of the rotary stage is always maintained; that is, even when the rotary stage rotates at any angle, the deviation of the distance from the focused light spot to the rotation axis of the rotary stage is less than 1 μm. (After correction) When the laser beam enters the galvanometer and the deviation of the distance from the focused light spot to the rotation axis of the rotary stage is less than 1 μm, the rotation error of the laser optical path is considered to be eliminated.

[0041] In the method of the present invention, when the rotary stage rotates, the sensor receives laser information (e.g., information on emission from the rotary stage, information on incidence from the rotary stage), senses the laser incidence information, and sends the real-time incidence information to the controller. The controller compares this real-time incidence information with the set position information to determine an offset value. If the offset value exceeds a set threshold, the controller drives the reflection mechanism to adjust and compensate the laser optical path in real time, and maintains the relative position between the laser optical path incident on the galvanometer and the center line of the rotary stage rotation axis after compensation.

[0042] The sensor is usually installed at the end where the laser enters or exits from the rotating stage to receive laser information. When installed at the exit end, the sensor rotates around the rotation axis of the rotating stage along with the rotating stage to receive laser information, and when installed after the reflector in particular, it receives laser information refracted by the reflector.

[0043] The reflecting mechanism typically includes at least one high-speed reflecting mirror, receives the laser from the ultrafast laser and commands from the controller, and adjusts the reflector to compensate for the laser beam path.

[0044] Another method for correcting path deviation when the laser pointing changes is to install a sensor at one end where the laser exits or enters the rotary stage when the rotary stage rotates, receive laser information, and send real-time incident information to the controller. The controller compares the real-time incident information with the set position information to obtain an offset value, and if the offset value exceeds a set threshold, activates the high-speed reflecting mirror.

[0045] The high-speed reflecting mirror reflects the laser beam emitted from the ultrafast laser, and, upon receiving commands from the controller, performs compensation on the laser beam path, maintaining the relative positional relationship between the laser beam path incident on the galvanometer after compensation and the center line of the rotation axis of the rotary stage.

[0046] Another method for correcting path deviation when the laser pointing changes is to install a sensor at one end where the laser exits or enters the rotary stage when the rotary stage rotates, receive laser information, and send real-time incident information to the controller. The controller compares the real-time incident information with the set position information to obtain an offset value, and if the offset value exceeds a set threshold, activates the high-speed reflecting mirror.

[0047] The high-speed reflecting mirror reflects the laser beam emitted from the rotary stage, and upon receiving a command from the controller, adjusts the angle of the reflector to compensate for the laser beam path (deviation that occurs) caused by the rotation of the rotary stage.

[0048] The method of the present invention is applicable to machining devices with multiple operating axes (e.g., 3-axis machine tools, 4-axis machine tools, 5-axis machine tools, etc.), and eliminates the influence of factors such as rotation of the rotary stage, stress, vibration, elastic deformation, temperature, and rotation error on the laser pointing and light spot position after focusing, and maintains the spatial distance between the laser light spot after focusing and the center of the rotation axis on the rotary stage surface even when the rotary stage is rotated at any angle.

[0049] To implement the above method and to facilitate application of the method of the present invention to a machining device, the present invention further provides a method for correcting path deviations when laser pointing changes: a rotation stage including a cavity for performing a rotational motion and accommodating the propagation of a laser beam path; an ultrafast laser that emits laser light and passes through the cavity and the rotation stage; a laser projection relay member that is installed on the rotary stage, rotates around the rotation axis of the rotary stage along with the rotary stage, receives the laser from the emission end of the cavity, changes the direction of the laser's optical path, and then emits the laser, and includes at least a first reflector and a second reflector; an aperture for receiving the beam reflected from the first reflector; An apparatus comprising:

[0050] The device of the present invention further includes a light emitting member that is arranged on the rotary stage, rotates together with the rotary stage around the rotation axis of the rotary stage, receives the laser emitted from the laser projection relay member, and focuses the laser within the range of the rotation axis.

[0051] The device of the present invention comprises: a sensor for acquiring real-time laser incidence information; a controller that receives real-time incident information from the sensor and compares it with preset position information to obtain a position offset value; a reflecting mechanism that receives the laser beam emitted from the ultrafast laser, and compensates for the laser beam path after receiving a command from the controller; Further includes:

[0052] In the device of the present invention, the reflecting mechanism includes at least one reflector. However, two reflectors are required to achieve a better laser path compensation solution. Furthermore, each reflector is arranged on a single frame, and each reflector has at least two adjustable degrees of freedom, i.e., at least two reflectors provide four or more degrees of freedom to implement the laser path compensation solution.

[0053] A specific implementation of the reflecting mechanism includes a third reflector and a fourth reflector, and the third reflector receives the laser and then reflects the laser to the fourth reflector, which receives the laser and then reflects the laser back toward the cavity.

[0054] The laser projection relay device of the present invention includes at least one reflector, which is a double-sided polished lens, and receives the laser beam reflected by the second reflector and then directly receives the laser beam from the exit end of the cavity. After changing the optical path direction of the laser beam, it can be used as the input laser beam for the galvanometer.

[0055] A sensor is installed after the reflector, and the beam is refracted (transmitted) through the reflector to observe and detect the laser light spot, and obtain real-time incident information of the laser.

[0056] In order to facilitate the use of the reflected laser as an incident laser for the galvanometer, a plurality of reflectors may be further provided to adjust the optical path of the reflected laser.

[0057] In the device provided by the present invention, the rotary stage may be, for example, but not limited to, an inner rotor rotary stage, an outer rotor rotary stage, a mechanically driven rotary stage, or a direct drive rotary stage, and is hollow to accommodate a cavity. The cavity within the rotary stage may have an outer wall, or the inner wall of the hollow structure within the rotor may be used as the outer wall of the cavity. In this case, the cavity is a hollow structure within the rotary stage, reducing the space occupied by the device.

[0058] In the device provided by the present invention, the laser projection relay member, the light emitting member, and the hollow rotary stage rotate synchronously. Specifically, the light emitting member is connected to the laser projection relay member and driven by the hollow rotary stage to rotate around the rotation axis.

[0059] The various devices provided by the present invention can be attached to a processing device, for example, by combining three linear motion axes, a workpiece fixing rotary motion axis, and a laser beam rotation axis to form a five-axis laser processing solution, which can process the workpiece along multiple axes and realize the manufacturing of products with complex and diverse structures. For example, a machine tool has at least three linear axes, and one linear axis is attached to the device of the present invention (e.g., installed on a plane defined by the X and Z axes and moving linearly along the Z axis), and the other linear axis is attached to a rotary positioning mechanism to drive the rotational positioning of the workpiece (e.g., the workpiece is installed on a plane defined by the X and Y axes). This eliminates the effects of factors such as stress, vibration, elastic deformation, temperature rise, and rotation error on the laser pointing and light spot position after focusing, and allows the rotary stage to be rotated at any angle without changing the spatial distance from the focused laser light spot to the center of the rotation axis on the rotary stage surface, improving the precision of laser processing and enabling laser processing of parts with various specifications.

[0060] There is also a processing device in which the rotation stage of the apparatus of the present invention is installed on a linear axis, and when the apparatus moves linearly, the focused light spot of the laser emitted by the light emitting member moves linearly, and when the light emitting member rotates around the rotation axis, the laser light spot is distributed on the rotation surface, making it suitable for processing various workpieces. [Effects of the Invention]

[0061] The beneficial effects achieved by the technical solution of the present invention are as follows: The method provided by the present invention uses an aperture to correct the propagation path when the laser pointing changes as the rotary stage rotates, selectively removing the portion of the beam that has been deviated due to the rotation (e.g., deviation in laser pointing), and allows the laser beam that has passed through the aperture (i.e., the non-deviated preset propagation path) to continue propagating along the preset path, changing its propagation direction through reflection, thereby maintaining the laser pointing to the workpiece in accordance with the preset, and maintaining a stable light spot shape acting on the workpiece, thereby meeting the requirements for precision machining. The method provided by the present invention uses a sensor to sense the position and pointing information of the laser light spot in real time, and adjusts the reflecting mechanism via a controller to compensate for offsets that occur in the laser light path, thereby eliminating the effects on the pointing of the focused laser and the light spot position caused by rotation, stress, vibration, elastic deformation, temperature rise, rotation error, etc. of the rotary stage. This ensures that the spatial distance between the focused laser light spot and the center of the rotation axis on the rotary stage surface remains constant regardless of the angle of the rotary stage, thereby improving the accuracy of laser processing. The method provided by the present invention allows the laser head of the ultrafast laser to be mounted vertically and pointing downward, and integrates the ultrafast laser into a processing device, making it easier to perform laser precision processing. The device provided by the present invention installs an aperture between two adjacent reflectors of a laser projection relay member, correcting the laser propagation path deviation from the preset due to factors such as rotation of the rotary stage, stress, vibration, elastic deformation, temperature rise, and rotation error. This allows low-cost modification of conventional processing devices to integrate ultrafast lasers into the processing device, and is useful for implementing precision laser processing. [Brief explanation of the drawings]

[0062] [Figure 1] FIG. 1 is an explanatory diagram of an embodiment of an apparatus used in conventional laser processing. [Figure 2] FIG. 1 is an explanatory diagram of an embodiment of a laser beam path in a conventional laser processing device. [Figure 3] FIG. 10 is an explanatory diagram of another embodiment of a laser beam path in an apparatus used in conventional laser processing. [Figure 4] FIG. 1 is an illustration of an embodiment of the method of the present invention. [Figure 5] FIG. 5 is an enlarged explanatory view of the aperture angle shown in FIG. [Figure 6] 1 is an illustration of one embodiment of an apparatus for carrying out the method of the present invention. [Figure 7] FIG. 2 is an illustration of another embodiment of an apparatus for carrying out the method of the present invention. [Figure 8]1 is an explanatory diagram of laser marking on a work surface when the work is processed using the device of the present invention. FIG. [Figure 9] FIG. 10 is an explanatory diagram of laser marking on the work surface after the restriction of the device of the present invention has been removed. DETAILED DESCRIPTION OF THE INVENTION

[0063] The technical solution of the present invention will be described in detail below with reference to the drawings. The embodiments of the present invention are for illustrating the technical solution of the present invention, but are not intended to limit it. The present invention will be described in detail with reference to preferred embodiments. However, as can be understood by those skilled in the art, modifications or equivalent substitutions can be made to the technical solution of the invention, and should be included in the scope of the claims of the present invention as long as they do not deviate from the spirit and scope of the technical solution of the present invention.

[0064] In the laser processing method provided by this embodiment, the laser beam emitted from the laser oscillator first enters a part of the cavity, exits the cavity, and then enters the laser projection relay member. The laser beam then changes its propagation path before being emitted. Finally, the laser beam is received by the light emitting member and emitted again to process the workpiece. The laser beam propagates within the cavity, along a straight line, or along a bending line. The laser beam propagates along a straight line at the exit end of the cavity. In a right-handed Cartesian coordinate system, the rotation axis is the A-axis, B-axis, or C-axis. The laser beam emitted from the light emitting member is distributed in a direction rotating around the rotation axis, and the laser beam is focused within the range of the rotation axis, i.e., within a circular plane with a radius of 100 mm centered on the rotation axis, and particularly focused on the rotation axis line. The laser beam's direction is changed by rotating the rotation axis to perform machining. In this embodiment, the cavity is in the Y-axis direction, the rotation axis is the B-axis, and the light emitting member rotates around the B-axis.

[0065] Fig. 1 is an explanatory diagram of one embodiment of a conventional laser processing apparatus. As shown in Fig. 1, this apparatus includes a laser oscillator 100, a cavity 200, a laser projection relay member 700, a light emitting member 300, and a rotation stage 400.

[0066] The laser oscillator 100 is disposed at one end of the cavity 200, and the laser beam 110 emitted from the laser oscillator 100 enters the cavity 200. In this embodiment, the cavity 200 has a straight tube shape, and the laser beam 110 emitted from the laser oscillator 100 propagates in a linear direction without being deflected after entering the cavity 200, and is emitted from the other end coaxially or parallel to the rotation axis of the rotation stage 400. The laser beam emitted from the cavity 200 changes direction due to the action of the laser projection relay member 700, and is then received by the light emitting member 300. The emitted laser beam 310 is focused within the range of the rotation axis 410 to process the workpiece.

[0067] In this embodiment, the laser projection relay member 700 includes a first reflecting mechanism 710 and a second reflecting mechanism 720. The first reflecting mechanism 710 receives the laser beam incident on the laser projection relay member and reflects the laser beam toward the second reflecting mechanism 720. The second reflecting mechanism 720 receives the laser beam 730 reflected from the first reflecting mechanism 710, and then reflects the laser beam 730 again and emits the laser beam toward the laser projection relay member.

[0068] The laser projection relay member 700 is driven by the rotary stage 400 and rotates around the rotation axis 410, receives the laser from the emission end of the cavity, changes the direction of the laser's optical path, and then emits the laser. The light emission member 300 rotates around the rotation axis 410 and emits the laser beam 310 that performs machining.

[0069] In a right-handed Cartesian coordinate system, the rotation stage 400 rotates around the Y-axis, with the B-axis (not shown) being the center of rotation. The cavity 200 has an axis that is coaxial with the B-axis (coaxial with the laser 110 in the figure, not shown). Because the light emitting member 300 rotates around the B-axis, the emitted laser light is distributed around the B-axis direction, allowing the laser to perform rotary machining. The cavity 200 is installed within the rotation stage 400, and a portion of the rotation stage 400 is located in a straight hollow cavity. The axis of the cavity is coaxial with the B-axis and also coaxial with the rotational symmetry axis of the rotation stage.

[0070] Even when the hollow rotary stage 400 rotates, the cavity 200 installed therein does not move, so the laser 110 that passes through the cavity 200 propagates along a straight line, does not generate deflection, and is always received by the light emitting member 300. When the light emitting member 300 continues to rotate around the B axis, a laser distribution is formed centered on the B axis rotation direction.

[0071] After this type of equipment is equipped with a multi-axis machining device, the intersection angle between the laser beam path 110 entering the cavity and the rotational stage axis 410 is maintained between 0 and 5°. As the rotary stage rotates, the laser projection relay element and the light output element also rotate around the rotational axis 410. The laser used for machining is emitted from the light output element 300 and rotates around the rotary stage rotation axis 410. The laser projection relay element rotates along the rotary stage, changing the laser pointing angle, for example, by 1°, 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, or more. In actual manufacturing, factors such as stress, vibration, temperature, and elastic deformation inevitably occur, causing the laser to stop propagating along the rotary stage axis during rotation, resulting in a deviation in laser propagation. After the misaligned laser beam is redirected through the laser projection relay member, the deviation from the set laser propagation path further increases, causing deviation in the laser beam 310 emitted by the light emitting member, which affects laser processing accuracy. Figures 2 and 3 are explanatory diagrams of another embodiment of the laser beam path in a conventional laser processing device. These diagrams show that if the relay member and the light emitting member rotate along with the rotary stage, the laser beam emitted from the light emitting member 300 cannot be directed to the same location if the laser beam path 110 incident on the cavity and the rotary stage rotation axis 410 are not coaxial. Therefore, the optical path must still be readjusted periodically when the actual distance and actual included angle between the laser beam path incident on the galvanometer and the center line of the rotary stage rotation axis deviate from the set distance and included angle, which wastes a lot of time and is disadvantageous for cost control.

[0072] Therefore, this embodiment provides a method for correcting path deviation when laser pointing changes, in which the laser emitted from the rotary stage 400 undergoes at least one reflection to change its propagation direction and then continues to propagate toward the aperture, allowing the laser beam that passes through the aperture to continue propagating along the preset path. Figure 4 is an explanatory diagram of one embodiment of the method of the present invention, and Figure 5 is an enlarged explanatory diagram of the aperture angle shown in Figure 4. As shown in Figures 4 and 5, in combination with Figure 1, the laser projection relay member rotates synchronously under the action of the rotary stage 400. During operation, factors such as stress, vibration, temperature, and elastic deformation affect beam 762, causing beam 761 to deviate and become beam 762. After the beams 761 and 762 are reflected by the first reflector 731, they propagate toward the aperture 750, and through the aperture 750, a laser beam 760 is obtained that conforms to the preset propagation path. That is, the propagation direction is changed by reflection. For example, after the propagation direction is changed by reflection, the beam enters the light emitting member 300, and the beam that deviates from the preset propagation path is corrected. When the laser rotates in synchronization with the rotary stage and the propagation direction changes by more than 180°, the direction of the laser toward the workpiece conforms to the preset, and the shape of the light spot acting on the workpiece also remains stable, thereby meeting the requirements for precision machining.

[0073] FIG. 6 is an explanatory diagram of an embodiment of an apparatus used to implement the method of the present invention. As shown in FIG. 6, the apparatus of this embodiment includes a rotation stage 400, an ultrafast laser 120, and a laser projection relay 700. The rotation stage 400 is hollow and includes a cavity that accommodates the propagation of the laser. The ultrafast laser 120 is mounted on a bracket 600, and the emitted laser beam 121 is reflected by a reflecting mechanism 800, changes direction, and enters the cavity 200. At the exit end of the cavity 200, the laser beam 121 propagates along a straight line.

[0074] The laser projection relay component 700 is mounted on the rotary stage 400 and rotates around the rotary stage rotation axis along with the rotary stage 400. It receives a laser beam from the exit end of the cavity, changes the direction of the laser's optical path, and then emits the laser beam, which includes at least a first reflector 731 and a second reflector 721. The aperture 750 is located between the first reflector 731 and the second reflector 721. After the laser beam's propagation direction is changed by reflection from the first reflector 731, it continues to propagate toward the aperture 750, allowing the laser beam that passes through the aperture 750 to continue propagating along a preset path. The total change in the laser propagation angle from when the laser beam enters the laser projection relay component until it is emitted reaches 180° or more. After the laser beam changes direction due to the action of the laser projection relay component 700, it is received by the galvanometer 320 of the light output component. The light output component rotates around the rotation axis, focusing the light within the range of the rotation axis.

[0075] To ensure that the laser's pointing toward the workpiece meets preset requirements and to improve the stability of the light spot shape acting on the workpiece, a pre-correction is performed before the laser beam enters the cavity, so that it propagates forward along the direction of the rotary stage's rotation axis (including parallel or coaxial). That is, the laser beam is pre-adjusted to be as coaxial or parallel as possible to the rotary stage's rotation axis. Alternatively, closed-loop pointing control is performed, whereby the laser's pointing toward the workpiece is adjusted in real time using a high-speed reflecting mirror and a sensor. For example, as the rotary stage rotates, a sensor also rotates around the rotary stage's rotation axis. The sensor is installed at the end of the rotary stage where the laser is emitted, receives laser information, and transmits real-time incident information to a controller. The controller compares the real-time incident information with the preset position information to determine an offset value. If the offset value exceeds a preset threshold, the reflecting mechanism is activated.

[0076] The reflecting mechanism receives the laser beam from the ultrafast laser, and after receiving instructions from the controller, compensates the laser beam path and maintains the relative position between the compensated laser beam path incident on the galvanometer and the center line of the rotation axis of the rotary stage.

[0077] FIG. 7 is an explanatory diagram of another embodiment of an apparatus for implementing the method of the present invention. As shown in FIG. 7, the inner wall of the hollow structure of the rotor is used as the outer wall of the cavity, and cavity 200 is a hollow structure cavity within the rotation stage. Ultrafast laser 120 is placed on bracket 600, and the emitted laser beam 121 is reflected by reflecting mechanism 800, changes direction, and enters cavity 200 again. At the exit end of cavity 200, laser beam 121 propagates along a straight line. After being affected by laser projection relay 700, the laser beam changes direction and is received by galvanometer 320 of the light emitting element. The light emitting element rotates around the rotation axis and focuses the light within the range of the rotation axis.

[0078] The laser projection relay element includes at least one reflector-based double-sided polished lens. In this embodiment, the laser projection relay element is installed on a second reflector 721 and a first reflector 731. Specifically, after the first reflector 731 receives the laser, it reflects the laser and causes the beam to propagate toward the aperture 750. After passing through the aperture 750, the propagation path conforms to the set path and propagates toward the second reflector 721. After the second reflector 721 receives the laser, it reflects the laser toward the galvanometer.

[0079] The sensor 900 is located behind the second reflector 721 and uses light transmitted through the reflector to detect the laser light spot from the exit end of the cavity, obtaining real-time position information of the laser. A controller (not shown) receives the real-time position information transmitted by the sensor 900, compares it with preset position information, and obtains a position offset value. If the position offset value exceeds a threshold, it indicates that the relative position between the laser light path and the rotation axis of the rotary stage cannot be maintained, and issues a command to the reflection mechanism. In this embodiment, two sensor elements are used to obtain information on the laser incident angle and information on the laser position on the sensor elements, obtaining more laser incident information.

[0080] After receiving a command from the controller, the reflecting mechanism 800 adjusts the laser beam received from the ultrafast laser to compensate for changes in the laser beam path in real time so that the relative position of the laser beam path 740 incident on the galvanometer and the center line of the rotation axis of the rotary stage is maintained. In this embodiment, the reflecting mechanism 800 includes a third reflector 810 and a fourth reflector 820, each of which is mounted on a separate frame. Each reflector has at least two adjustable degrees of freedom, i.e., at least two reflectors provide four or more degrees of freedom, implementing a laser compensation technology. Specifically, the third reflector 810 reflects the laser beam to the fourth reflector 820, which then reflects the laser beam toward the cavity, thereby maintaining the relative position of the laser beam path incident on the galvanometer and the laser beam path of the rotation axis of the rotary stage. A preferred AOI of the third reflector 810 and the fourth reflector 820 is 22.5°.

[0081] Alternatively, a sensor 900 may be installed before the laser enters the rotating stage 400, and the light transmitted through the reflector may be used to detect the laser spot from the exit end of the cavity to obtain real-time position information of the laser. Alternatively, a reflecting mechanism 800 may be placed on the rotating stage 400, which is also considered an equivalent replacement for this technical solution.

[0082] The apparatus provided in each of the above embodiments is attached to a processing device and, for example, combines three linear motion axes, one rotary motion axis for fixing the workpiece, and one laser beam rotation axis to form a spatial five-axis laser processing technology solution, which can perform multi-axis machining on the workpiece to manufacture products with complex and diverse structures, particularly suitable for precision machining of long-axis parts. For example, a machine tool has at least three linear axes, and the apparatus of the present invention is installed on one linear axis (e.g., installed on a plane defined by the X-axis and Z-axis and moving linearly along the Z-axis), and a rotary positioning mechanism is installed on the other linear axis to drive the rotational positioning of the workpiece to be processed (e.g., installed on a plane defined by the X-axis and Y-axis). This eliminates the situation where the relative position between the beam and the rotary stage rotation axis cannot be maintained due to factors such as stress, vibration, elastic deformation, or temperature, thereby improving the precision of laser processing and helping to perform laser processing on parts with various specifications.

[0083] The device shown in Figure 6 of this embodiment was installed on a machine tool, and a sample card was placed on the focal plane. The sample card was rotated 180 degrees by turning on the laser and driving the B axis in accordance with the rotation of the B axis, and then the sample card was observed under a 200x microscope. The only etching traces were circular patterns whose diameter corresponded to the diameter of the light spot (see Figure 8), which indicates that the light spot only rotates around its own axis and does not displace as the B axis rotates.

[0084] After removing the aperture from the above device, the same test was performed and the sample card was observed under a 200x microscope. The etching marks that occurred were as shown in Figure 9. Comparing with Figure 8, after removing the aperture, the position of the laser focal point drifted with the rotation of the B axis, and the maximum deviation in the experimental device reached more than four times the diameter of the light spot, clearly failing to meet the requirements for precision processing. [Explanation of symbols]

[0085] 100 Laser Oscillator 110 Laser 120 Ultrafast Laser 121 Laser 200 cavity 300 Light emitting member 310 Laser 320 Galvanometer 400 rotation stage 410 Rotational Axis 600 bracket 700 Laser projection relay component 710 1st reflection mechanism 720 Second reflection mechanism 721 Second Reflector 730 Laser 731 First Reflector 740 Laser path 750 aperture 760 Laser Beam 761 Beam 762 Beam 800 Reflection mechanism 810 Third Reflector 820 4th reflector 900 Sensors

Claims

1. A method for correcting path deviation when laser pointing changes, characterized in that when the pointing direction of a laser changes as the rotary stage rotates, the laser whose propagation direction has been changed by reflection continues to propagate toward an aperture, and the laser beam that has passed through the aperture continues to propagate along a preset path.

2. 10. The method of claim 1, further comprising: pre-correcting the laser before it enters the cavity; and propagating the laser beam forward along the extension of the axis of rotation of the rotary stage.

3. 10. The method of claim 1, further comprising performing real-time closed-loop adjustment of the pointing of the laser relative to the workpiece through a reflector and a sensor before the beam passes through the aperture.

4. The method according to claim 1, further comprising: installing a sensor at one end of the rotary stage that emits or inputs laser light, receiving laser information, and transmitting real-time input information to a controller; the controller comparing the real-time input information with preset position information to obtain an offset value; and driving a high-speed reflecting mirror when the offset value exceeds a preset threshold value. The high-speed reflecting mirror reflects the laser light emitted from the ultrafast laser, and compensates for the laser after receiving a command from the controller, thereby maintaining the relative positional relationship between the laser light path incident on the galvanometer and the center line of the rotary stage rotation axis after compensation.

5. The method according to claim 1, further comprising: installing a sensor at one end of the rotary stage that emits or emits laser light, receiving laser information, and transmitting real-time incident information to a controller; the controller comparing the real-time incident information with preset position information to obtain an offset value; and driving a high-speed reflecting mirror that reflects the laser light emitted from the rotary stage when the offset value exceeds a preset threshold value. The high-speed reflecting mirror then adjusts the angle of the reflector after receiving a command from the controller to compensate for the deviation of the laser light path caused by the rotation of the rotary stage.

6. 2. The method of claim 1, wherein the laser is emitted from the cavity of the rotating rotary stage, undergoes at least one reflection, changes its propagation direction, and again follows the rotation of the rotary stage.

7. 10. The method of claim 1, applied to a machining device having multiple axes of motion, for adjusting the laser pointing to a workpiece to a preset to maintain stability and improve laser machining accuracy.

8. 2. The method according to claim 1, which is applied to a machining device having multiple motion axes, and maintains the shape of the light spot acting on the workpiece stable, thereby satisfying the requirements for precision machining.

9. A machining device characterized in that it employs the method according to claim 1.

10. an ultrafast laser that is a pulsed laser whose output laser pulse width is on the picosecond level or less, the ultrafast laser being a pulsed laser that emits a laser beam through the cavity and passes through the rotary stage, the ultrafast laser being a pulsed laser whose output laser pulse width is on the picosecond level or less, the ultrafast laser projection relay member that is mounted on the rotary stage and rotates around the rotation axis of the rotary stage along with the rotary stage, receives the laser beam from the exit end of the cavity, changes the direction of the laser beam path, and then emits the laser beam, the laser projection relay member including at least a first reflector, and an aperture that receives the beam reflected from the first reflector.

11. The device according to claim 10, further comprising a light emitting member that is mounted on the rotary stage, rotates around the rotation axis of the rotary stage along with the rotary stage, receives the laser emitted from the laser projection relay member, and focuses the laser within the range of the rotation axis.

12. 11. The apparatus of claim 10, further comprising: a sensor for obtaining real-time incident information of the laser; a controller for receiving the real-time incident information emitted by the sensor and comparing it with preset position information to obtain a position offset value; and a reflecting mechanism for receiving the laser emitted from the ultrafast laser, and after obtaining a command from the controller, compensating the laser optical path after reflection, so as to keep the distance from the focused light spot to the rotation axis of the rotary stage constant, i.e., keeping the deviation of the distance at any angle of the rotary stage within 1 μm.

13. 13. The apparatus of claim 12, wherein the reflecting mechanism includes at least two high-speed reflecting mirrors, each high-speed reflecting mirror having at least two adjustable degrees of freedom.

14. 13. The apparatus of claim 12, wherein the reflecting mechanism includes a third reflector and a fourth reflector, the third reflector receiving the laser and then reflecting the laser to the fourth reflector, and the fourth reflector receiving the laser and then reflecting the laser toward the cavity.

15. A machining device comprising an apparatus according to claim 10.

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