Additive and subtractive optical system and additive and subtractive forming method

Abstract

The invention belongs to the field of optics, and relates to an additive and subtractive optical system and an additive and subtractive forming method, the additive and subtractive optical system comprises a forming light generating device, a 3D galvanometer group, a visual monitor and window glass; the forming light generating device generates forming laser; the 3D galvanometer set and the window glass are sequentially arranged on the light path where the forming laser is located from front to back. The monitoring visual field of the visual monitor covers the window glass; and the forming laser passes through the window glass and then enters the additive and subtractive working surface. The invention provides an additive and subtractive material optical system and an additive and subtractive material forming method which can ensure smooth proceeding of additive and subtractive material processing, ensure forming quality and improve forming efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of optics, and relates to a laser optical system, and in particular to an additive and subtractive optical system and an additive and subtractive forming method used in 3D printing. Background Art

[0002] Ultrafast lasers generally refer to lasers with pulse widths of less than 10ps. The important technical indicators for measuring ultrafast lasers are pulse width and single pulse energy. With the remarkable progress made in laser technology, ultrafast lasers are rapidly developing towards a trend of decreasing pulse width and increasing single pulse energy. Although current ultrafast laser technology can already achieve laser output with attosecond pulse widths, there are still limitations in pulse compression modules in high-power, high-pulse energy scenarios. In order to achieve low pulse width compression, a single level of pulse width compression is often unable to meet the pulse width compression effect, and multi-level pulse width compression is required to achieve a high compression ratio. There are two commonly used compression technologies, one is hollow-core fiber pulse width compression and the other is multi-pass cavity pulse width compression technology.

[0003] At present, there are related public patents that adopt the method of installing a mechanical subtractive processing device in the traditional laser selective melting forming (or laser powder bed melting forming) equipment, such as invention applications with publication numbers CN104493491A, CN106273440A and CN113967737A. However, these methods have greatly changed the current industrial SLM equipment, the equipment is complex, the cost is extremely high, and the introduction of machining leads to low overall processing efficiency. At the same time, patent applications with publication numbers CN104923786A, CN113977087A, CN111992712A, CN111992879A and CN114535621A and utility model patents with authorization announcement numbers CN205660160U and CN212598870U disclose a dual-optical path system solution, which introduces two laser beams into the forming area through two sets of beam expansion collimating mirrors, scanning galvanometers, and F-theta field mirrors. Due to the presence of two sets of scanning galvanometers and F-theta focusing mirrors, the equipment cost is relatively high, and the overlap of the two laser beams in space is difficult to adjust, as well as problems such as motion accuracy.

[0004] The invention application with publication number CN111992877A discloses a dual-station laser additive and subtractive composite manufacturing device, in which continuous laser additive manufacturing and laser subtractive manufacturing are located in two stations, the position of the optical path system remains unchanged, and the station switching is achieved by translating the forming cylinder. This solution results in the equipment volume being doubled compared to conventional laser selective melting forming (or laser powder bed melting forming), and the equipment cost increases significantly. In addition, the reciprocating forming cylinder during the forming process will lead to low forming efficiency, and spatial position overlap is also quite difficult, especially under large loads.

[0005] The invention application with publication number CN114535610A discloses a dual-beam synchronous laser selective melting forming device and method, which uses a beam combiner to combine a Gaussian beam and a flat-top beam to improve the efficiency of additive manufacturing. This patent does not involve laser additive and subtractive technology. Similarly, the invention application with publication number CN114643369A discloses a dual-beam composite additive manufacturing scanning method, which also does not involve laser subtraction and high-precision forming.

[0006] The invention application with publication number CN115889820A and the invention application with publication number CN110977152A disclose a device for combining two laser beams and an additive manufacturing method. After combining, the focused spot sizes of the two beams are inconsistent, and the patent does not involve laser additive and subtractive technology.

[0007] The invention application with publication number CN115026313A discloses a device and method for adjusting the overlap of the trajectories of two beams of light by using the first reflector of the scanning galvanometer, which realizes the laser additive processing of two beams of light in controllable time periods, but the patent does not involve aspects such as laser subtraction. The invention application with publication number CN110587118A discloses a device in which two beams of light can enter the laser selective melting equipment simultaneously / in time periods for additive / subtractive manufacturing. The scheme adopts an unconventional spherical emitting mirror with a small curvature and two plane reflectors, which realizes that the reflected beams of the two beams of light are located on the same straight line, but the scheme is not easy to control and cannot guarantee the spatial overlap of the two beams of light during the forming process. In addition, the patent does not disclose relevant schemes and methods for laser subtraction. The utility model patent with the authorization announcement number CN206326260U discloses a device for laser additive and subtractive material using infrared laser and green laser. The patent uses a 45° mirror with high transmittance of 1064nm infrared laser and a high reflectance of 532nm green laser to realize dual-wavelength laser sharing a set of optical path systems to realize infrared laser additive and green laser subtractive material. However, the patent is mainly aimed at the manufacture of hollow overhanging structures in parts and components, and does not mention the aspect of laser high-precision additive and subtractive material. The invention application with the publication number CN110369725A discloses a device and method for laser composite additive and subtractive material. The device uses a continuous / ultrafast laser composite method for laser additive and subtractive material processing, but does not mention the beam switching scheme, that is, no specific switching device structure for continuous laser and ultrafast pulse laser is given. It can be seen that the current solutions for the poor surface quality of laser additive manufacturing parts are composite mechanical subtractive processing and continuous / ultrafast laser composite solutions. In the dual-beam switching scheme, dual optical paths and dual stations are mainly used, and there are no single optical path, continuous / short pulse and ultrashort pulse dual laser composite devices and methods. The invention application with publication number CN117182120 A discloses a solution of optical path switching to achieve the solution of increasing and reducing materials. During the switching process, there is still a problem of repeatability between the dual optical paths, which will cause the problem of non-overlapping of the scanning areas of the increasing and reducing materials after long-term use.

[0008] However, in the process of additive and subtractive materials, whether switching the optical path or working in multiple stations, there is a possibility that powder will reach the window glass during processing. In the process of using laser processing for additive and subtractive materials, the problem of powder splashing onto the window glass causing processing abnormalities is not considered. Summary of the invention

[0009] In order to solve the above technical problems existing in the background technology, the present invention provides an additive and subtractive optical system and an additive and subtractive forming method which can ensure smooth additive and subtractive processing, ensure forming quality and improve forming efficiency.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] An additive and subtractive optical system, characterized in that: the additive and subtractive optical system includes a shaping light generating device, a 3D galvanometer group, a visual monitor and a window glass; the shaping light generating device generates a shaping laser; the 3D galvanometer group and the window glass are arranged in sequence from front to back on the optical path where the shaping laser is located; the monitoring field of the visual monitor covers the window glass; the shaping laser passes through the window glass and is incident on the additive and subtractive working surface.

[0012] The above-mentioned shaped light generating device includes a long pulse laser, an ultrafast laser, a first reflector and a beam combining mirror; the long pulse laser emits a long pulse laser; the ultrafast laser emits an ultrafast pulse laser; the first reflector is placed on the optical path of the long pulse laser; the ultrafast pulse laser and the long pulse laser reflected by the first reflector are incident on the beam combining mirror together and form a shaped laser after passing through the beam combining mirror.

[0013] The above-mentioned forming light generating device also includes a second reflector and a third reflector; the first reflector and the second reflector are arranged in sequence from front to back on the optical path of the long pulse laser; the third reflector is arranged on the optical path of the ultrafast pulse laser; the long pulse laser is reflected by the first reflector and the second reflector in sequence and then incident on the beam combining mirror; the ultrafast pulse laser is reflected by the third reflector and then incident on the beam combining mirror.

[0014] The wavelength of the long pulse laser is 1064nm or 532nm; the wavelength of the ultrafast pulse laser is 1030nm or 515nm.

[0015] The 3D galvanometer group comprises a first movable lens, a first light-transmitting mirror and a second movable lens; the first movable lens, the first light-transmitting mirror, the second movable lens and the window glass are arranged in sequence from front to back on the optical path where the forming laser is located.

[0016] The above-mentioned 3D galvanometer group also includes a first driving member, which is connected to the first movable lens and drives the first movable lens to move freely along the optical axis where the forming laser is located; the first driving member is a voice coil motor or a linear motor.

[0017] The above-mentioned 3D galvanometer group also includes a second driving member; the second driving member is connected to the second movable lens and drives the second movable lens to move freely along the optical axis where the forming laser is located; the second driving member is a linear motor or a voice coil motor.

[0018] The above-mentioned 3D galvanometer group also includes a second light-transmitting mirror, a fifth reflector and a fourth reflector; the first movable lens, the first light-transmitting mirror, the second movable lens, the second light-transmitting mirror, the fourth reflector, the fifth reflector and the window glass are arranged in sequence from front to back on the optical path where the forming laser is located; the visible light transmitted from the window glass is reflected by the fifth reflector, the fourth reflector and the second light-transmitting mirror in sequence and then incident on the visual monitor.

[0019] The first movable lens and the second movable lens are both liquid lenses.

[0020] A method for additive and subtractive forming based on the aforementioned additive and subtractive optical system, characterized in that the method comprises the following steps:

[0021] 1) Turn on the long pulse laser to generate a long pulse laser, which passes through the 3D galvanometer group and the window glass and is incident on the additive and subtractive material working surface to perform additive manufacturing on the current forming layer; then turn off the long pulse laser and turn on the ultrafast laser, which passes through the 3D galvanometer group and the window glass and is incident on the additive and subtractive material working surface to perform subtractive removal manufacturing on the current surface;

[0022] 2) After the current forming layer is completed, monitor the window glass through a visual monitor to see if there is powder aggregation; if so, proceed to step 3); if not, repeat steps 1) and 2) until the additive manufacturing and / or subtractive manufacturing of all forming layers are completed;

[0023] 3) adjusting the initial position of the second movable lens along the axis of the forming laser, turning on the ultrafast laser and turning off the long pulse laser, removing the powder gathered on the window glass by the ultrafast pulse laser emitted by the ultrafast laser, and after the powder is completely removed, restoring the initial position of the second movable lens along the axis of the forming laser, and then proceeding to step 4);

[0024] 4) Repeat steps 1) to 3) until the additive manufacturing and / or subtractive manufacturing of all the shaping layers are completed.

[0025] The advantages of the present invention are:

[0026] The present invention provides an additive and subtractive optical system and an additive and subtractive forming method, wherein the additive and subtractive optical system includes a forming light generating device, a 3D galvanometer group, a visual monitor and a window glass; the forming light generating device generates a forming laser; the 3D galvanometer group and the window glass are sequentially arranged on the optical path where the forming laser is located from front to back; the monitoring field of the visual monitor covers the window glass; the forming laser passes through the window glass and is incident on the additive and subtractive working surface. The present invention mainly uses ultrafast laser processing to vaporize the powder on the window glass. In the process of using laser additive and subtractive materials, not only long pulse laser additive and short pulse subtractive are retained, but also the ultrafast laser optical path is used to remove the window glass powder at the same time. In addition, the coaxial visual observation on the window glass ensures a first-class solution for observing the window glass powder during the processing. Pulse laser, especially ultrashort pulse laser, has extremely high peak power due to its extremely short pulse width, which instantly vaporizes and removes the material. Therefore, the present invention introduces pulsed laser into traditional laser selective melting forming (or laser powder bed melting forming) equipment, which can not only ensure the smooth progress of additive and subtractive processing, but also optimize the surface quality of parts in situ and further improve the forming efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the additive and subtractive optical system provided by the present invention;

[0028] in:

[0029] 1-long pulse laser; 2-ultrafast laser; 3-first reflector; 4-second reflector; 5-third reflector; 6-beam combiner; 7-first movable lens; 8-first light-transmitting mirror; 9-second movable lens; 10-second light-transmitting mirror; 11-visual monitor; 12-fifth reflector; 13-fourth reflector; 14-window glass; 15-additive and subtractive working surface. DETAILED DESCRIPTION

[0030] The technical problem to be solved by the present invention is as follows: in the process of adding or subtracting materials, the same 3D galvanometer is used and set to scan at different processing distances. In addition, a visual module is added to the optical path to determine whether there are powder residues and other problems on the window glass.

[0031] Based on this technical problem, the present invention first provides an additive and subtractive optical system, including a forming light generating device, a 3D galvanometer group, a visual monitor 11 and a window glass 14; the forming light generating device generates a forming laser; the 3D galvanometer group and the window glass 14 are arranged in sequence from front to back on the optical path where the forming laser is located; the monitoring field of the visual monitor 11 covers the window glass 14; the forming laser passes through the window glass 14 and is incident on the additive and subtractive working surface 15.

[0032] The shaping light generating device includes a long pulse laser 1, an ultrafast laser 2, a first reflector 3 and a beam combiner 6; the long pulse laser 1 emits a long pulse laser; the ultrafast laser 2 emits an ultrafast pulse laser; the first reflector 3 is placed on the optical path of the long pulse laser; the ultrafast pulse laser and the long pulse laser reflected by the first reflector 3 are incident on the beam combiner 6 together and form a shaping laser after passing through the beam combiner 6. The shaping light generating device also includes a second reflector 4 and a third reflector 5; the first reflector 3 and the second reflector 4 are sequentially arranged on the optical path of the long pulse laser from front to back; the third reflector 5 is arranged on the optical path of the ultrafast pulse laser; the long pulse laser is sequentially reflected by the first reflector 3 and the second reflector 4 and then incident on the beam combiner 6; the ultrafast pulse laser is reflected by the third reflector 5 and then incident on the beam combiner 6. The wavelength of the long pulse laser is 1064nm or 532nm; the wavelength of the ultrafast pulse laser is 1030nm or 515nm.

[0033] The 3D galvanometer group includes a first movable lens 7, a first light-transmitting mirror 8 and a second movable lens 9; the first movable lens 7, the first light-transmitting mirror 8, the second movable lens 9 and the window glass 14 are sequentially arranged from front to back on the optical path where the forming laser is located. The 3D galvanometer group also includes a first driving member, which is connected to the first movable lens 7 and drives the first movable lens 7 to move freely along the optical axis where the forming laser is located; the first driving member is a voice coil motor or a linear motor. The 3D galvanometer group also includes a second driving member; the second driving member is connected to the second movable lens 9 and drives the second movable lens 9 to move freely along the optical axis where the forming laser is located; the second driving member is a linear motor or a voice coil motor. The 3D galvanometer group also includes a second light-transmitting mirror 10, a fifth reflector 12 and a fourth reflector 13; the first movable lens 7, the first light-transmitting mirror 8, the second movable lens 9, the second light-transmitting mirror 10, the fourth reflector 13, the fifth reflector 12 and the window glass 14 are sequentially arranged on the optical path of the forming laser from front to back; the visible light transmitted from the window glass 14 is sequentially reflected by the fifth reflector 12, the fourth reflector 13 and the second light-transmitting mirror 10 and then incident on the visual monitor 11. The first movable lens 7 and the second movable lens 9 are both liquid lenses.

[0034] The first movable lens 7 and the first light-transmitting mirror 8 of the 3D galvanometer group used in the present invention are consistent with the lenses of the general 3D galvanometer, and the size of the light spot is adjusted in real time by a voice coil motor or a linear motor. The second movable lens 9 controls the distance plane of the focusing position by a linear motor or a voice coil motor, and the galvanometer reflector is controlled by a conventional galvanometer. All lenses can be metal-coated and compatible with multiple bands, or only adjacent bands can be used. It is composed according to the actual use situation. The second movable lens 9 can also use a liquid lens as a distance adjustment. The present invention uses the same 3D galvanometer group for material addition and subtraction, regardless of whether it is a similar band or a dual band. The 3D galvanometer group is mainly used to realize the change of the processing distance, and the ultrafast optical path is used for scanning, so as to realize the removal of window glass powder by ultrafast light. The lens movement can use various schemes, including voice coil motors, liquid lenses, etc., mainly to achieve movement in the Z-axis direction. Coaxial vision is used for judgment during the processing process, and the focus of the coaxial vision is the window glass surface, rather than the general working processing surface.

[0035] The present invention combines the long pulse laser used for additive manufacturing, such as (1064nm or 532nm), with the ultrafast pulse laser (1030nm or 515) or switches them into a 3D galvanometer group, and combines the long pulse laser and the ultrafast pulse laser together through a reflector group and a beam combining mirror and enters the 3D galvanometer. The processing process is consistent with the normal additive and subtractive material. The first two lenses and the galvanometer are adjusted to achieve scanning processing within the processing range. The conventional processing logic is powdering. The long pulse laser is used for additive manufacturing and the ultrafast pulse laser is used for subtractive manufacturing. After each layer of processing is completed, coaxial monitoring vision is used to collect images to determine whether there is powder residue on the window glass sheet. If the residue is found, some pre-determined positions are adjusted for scanning, the third lens is moved, and the galvanometer is used to scan, and the ultrafast laser is turned on to achieve the removal of powder residue. After each scan, coaxial monitoring vision is performed to determine that there is no residue, and the third lens continues to return to its original position to repeat the additive and subtractive material processing of the next layer. Specifically, the additive and subtractive material forming method provided by the present invention includes the following steps:

[0036] 1) Turn on the long pulse laser 1 to generate a long pulse laser, and the long pulse laser passes through the 3D galvanometer group and the window glass 14 and is incident on the additive and subtractive material working surface 15, and performs additive manufacturing on the current forming layer; then turn off the long pulse laser 1 and turn on the ultrafast laser 2, and the ultrafast laser 2 passes through the 3D galvanometer group and the window glass 14 and is incident on the additive and subtractive material working surface 15, and performs subtractive removal manufacturing on the current surface;

[0037] 2) After the current forming layer is completed, monitor the window glass 14 by the visual monitor 11 to see if there is powder aggregation; if so, proceed to step 3); if not, repeat steps 1) and 2) until the additive manufacturing and / or subtractive manufacturing of all forming layers are completed;

[0038] 3) adjusting the initial position of the second movable lens 9 along the axial direction where the forming laser is located, turning on the ultrafast laser 2 while turning off the long pulse laser 1, removing the powder gathered on the window glass 14 by the ultrafast pulse laser emitted by the ultrafast laser 2, and after the powder is completely removed, restoring the initial position of the second movable lens 9 along the axial direction where the forming laser is located, and then proceeding to step 4);

[0039] 4) Repeat steps 1) to 3) until the additive manufacturing and / or subtractive manufacturing of all the shaping layers are completed.

Claims

1. An additive and subtractive optical system, characterized in that: The additive and subtractive material optical system comprises a shaping light generating device, a 3D galvanometer group, a visual monitor (11) and a window glass (14); the shaping light generating device generates shaping laser; the 3D galvanometer group and the window glass (14) are arranged in sequence from front to back on the optical path where the shaping laser is located; the monitoring field of the visual monitor (11) covers the window glass (14); the shaping laser passes through the window glass (14) and is incident on the additive and subtractive material working surface (15).

2. The additive and subtractive optical system according to claim 1, characterized in that: The shaping light generating device comprises a long pulse laser (1), an ultrafast laser (2), a first reflecting mirror (3) and a beam combining mirror (6); the long pulse laser (1) emits long pulse laser; the ultrafast laser (2) emits ultrafast pulse laser; the first reflecting mirror (3) is placed on the optical path of the long pulse laser; the ultrafast pulse laser and the long pulse laser reflected by the first reflecting mirror (3) are incident on the beam combining mirror (6) together and form shaping laser after passing through the beam combining mirror (6).

3. The additive and subtractive optical system according to claim 2, characterized in that: The shaping light generating device further comprises a second reflecting mirror (4) and a third reflecting mirror (5); the first reflecting mirror (3) and the second reflecting mirror (4) are arranged in sequence from front to back on the optical path where the long pulse laser is located; the third reflecting mirror (5) is arranged on the optical path where the ultrafast pulse laser is located; the long pulse laser is reflected by the first reflecting mirror (3) and the second reflecting mirror (4) in sequence and then incident on the beam combining mirror (6); the ultrafast pulse laser is reflected by the third reflecting mirror (5) and then incident on the beam combining mirror (6).

4. The additive and subtractive optical system according to claim 3, characterized in that: The wavelength of the long pulse laser is 1064 nm or 532 nm; the wavelength of the ultrafast pulse laser is 1030 nm or 515 nm.

5. The additive and subtractive optical system according to claim 1, 2, 3 or 4, characterized in that: The 3D galvanometer group comprises a first movable lens (7), a first light-transmitting mirror (8) and a second movable lens (9); the first movable lens (7), the first light-transmitting mirror (8), the second movable lens (9) and the window glass (14) are arranged in sequence from front to back on the optical path of the forming laser.

6. The additive and subtractive optical system according to claim 5, characterized in that: The 3D galvanometer group also includes a first driving member, which is connected to the first movable lens (7) and drives the first movable lens (7) to move freely along the optical axis where the forming laser is located; the first driving member is a voice coil motor or a linear motor.

7. The additive and subtractive optical system according to claim 6, characterized in that: The 3D galvanometer group also includes a second driving member; the second driving member is connected to the second movable lens (9) and drives the second movable lens (9) to move freely along the optical axis where the forming laser is located; the second driving member is a linear motor or a voice coil motor.

8. The additive and subtractive optical system according to claim 7, characterized in that: The 3D galvanometer group also includes a second light-transmitting mirror (10), a fifth reflector (12) and a fourth reflector (13); the first movable lens (7), the first light-transmitting mirror (8), the second movable lens (9), the second light-transmitting mirror (10), the fourth reflector (13), the fifth reflector (12) and the window glass (14) are arranged in sequence from front to back on the optical path where the forming laser is located; the visible light transmitted from the window glass (14) is reflected by the fifth reflector (12), the fourth reflector (13) and the second light-transmitting mirror (10) in sequence and then incident on the visual monitor (11).

9. The additive and subtractive optical system according to claim 8, characterized in that: The first movable lens (7) and the second movable lens (9) are both liquid lenses.

10. A method for additive and subtractive forming based on the additive and subtractive optical system according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: 1) Turning on the long pulse laser (1) to generate a long pulse laser, the long pulse laser passes through the 3D galvanometer group and the window glass (14) and then enters the additive and subtractive material working surface (15) and performs additive manufacturing on the current forming layer; then turning off the long pulse laser (1) and turning on the ultrafast laser (2), the ultrafast laser (2) passes through the 3D galvanometer group and the window glass (14) and then enters the additive and subtractive material working surface (15) and performs subtractive manufacturing on the current surface; 2) After the current forming layer is completed, monitor the window glass (14) by a visual monitor (11) to see whether there is powder aggregation; if so, proceed to step 3); if not, repeat steps 1) and 2) until the additive manufacturing and / or subtractive manufacturing of all forming layers are completed; 3) adjusting the initial position of the second movable lens (9) along the axis of the forming laser, turning on the ultrafast laser (2) and turning off the long pulse laser (1), removing the powder gathered on the window glass (14) by the ultrafast pulse laser emitted by the ultrafast laser (2), and after the powder is completely removed, restoring the initial position of the second movable lens (9) along the axis of the forming laser, and then performing step 4); 4) Repeat steps 1) to 3) until the additive manufacturing and / or subtractive manufacturing of all the shaping layers are completed.

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