A long-life water guide laser processing head device suitable for high power

Abstract

The application discloses a long-life water guide laser processing head device suitable for high power, which comprises a shell, a main water inlet channel and a ring-shaped cooling water cavity which are independently arranged above and below, a back pressure water outlet device is arranged at the outlet of the main water inlet channel, high-pressure water is sprayed from 360-degree direction obliquely downward through the back pressure water outlet device, and is gathered into a uniform and thin water beam to form a water jet of water guide laser. A driving cooling type polarizing protection ring is coaxially fixed between the two water cavities, the inner wall of the ring has a high-absorptive coating, and the ring body is internally provided with a ring-shaped cooling micro-flow channel which is communicated with the ring-shaped cooling water cavity and is used for locally absorbing and removing a large amount of scattered laser energy generated during high-power processing. The anti-back-splashing protection cover installed at the lower end of the shell serves as a physical barrier to block large-particle slag. Through the cooperation of the independent double water cavities, the back pressure water outlet device, the driving cooling polarizing ring and the anti-back-splashing protection cover, the continuous running time and the reliability of the processing head under high power are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of high-power laser processing technology, and in particular to a long-life water-guided laser processing head device suitable for high-power lasers. Background Technology

[0002] Water-guided laser processing technology utilizes high-pressure water jets as "optical fibers" to guide the transmission of a laser beam, offering advantages such as a small heat-affected zone and narrow kerf in precision machining of semiconductors, high-temperature alloys, and composite materials. However, when laser power is increased to over 200W (high-power continuous or long-pulse mode) to pursue processing efficiency, the lifespan of the processing head decreases sharply. The main bottlenecks include: Scattered laser heat accumulation: At high power, even if the surface scattering rate of optical components is only 1%~2%, the absolute power of the scattered light can reach several watts to tens of watts. This scattered light irradiates the cavity walls, seals, and nozzle area, causing severe heat accumulation. Actual measurements show that after a conventional machining head operates under a 250W laser for 5 minutes, the nozzle seat temperature can exceed 150℃, leading to carbonization of the sealing ring and distortion of the water jet morphology. If this scattered light is not blocked, it will propagate directly downwards, heating the nozzle seat, seals, and even the annular cooling water cavity, causing seal failure, uneven water curtain, or thermal deformation, severely affecting the lifespan of the machining head.

[0003] Processing Powder and Slag Splashing: When a high-speed water jet impacts a workpiece, it generates a large amount of micron-sized powder, slag, and water mist, which bounce upwards with high kinetic energy. These contaminants easily adhere to the outer surface of the optical window and the nozzle exit, causing a decrease in laser transmittance, distortion of the water jet shape, and even clogging of the nozzle, forcing frequent shutdowns for cleaning.

[0004] Limited protective measures: Existing technologies mostly employ single-layer baffles, external air curtains, or simple cooling water channels, which cannot simultaneously address the issues of scattered light and powder splashing. Furthermore, they suffer from low cooling efficiency and insufficient protective coverage. Integrating protection and cooling functions into a compact space requires resolving technical contradictions such as the isolation between high-pressure and low-pressure cooling water circuits, and the interplay between scattered light interception and thermal management.

[0005] Therefore, this invention provides a long-life processing head configuration that can effectively manage scattered light heat, powder contamination, and thermal deformation for high-power (≥200W continuous laser) applications. Summary of the Invention

[0006] To address the technical problems existing in the background art, the present invention proposes a long-life processing head device suitable for high-power water-guided laser processing.

[0007] The present invention proposes a high-power, long-life water-guided laser processing head device, comprising: a housing, a coupling cavity, a high-pressure water inlet, a main water inlet channel, a back pressure water outlet device, a nozzle mounting base, and a replaceable nozzle core; The shell has two independent water chambers, one above the other. The upper coupling chamber is connected to the main water inlet channel, which is connected to an external high-pressure water source through a high-pressure water inlet. The lower annular cooling water chamber is connected to an external low-pressure water source through a cooling water inlet. A back pressure outlet device is provided at the outlet of the main water inlet channel. The back pressure outlet device has multiple symmetrical oblique converging water channels distributed in a ring. The bottom of the back pressure outlet device is provided with an outlet that communicates with the nozzle mounting seat, and the replaceable nozzle core is installed on the nozzle mounting seat. A polarizing protection ring is coaxially fixed between the coupling cavity and the nozzle mounting seat. An annular cooling microchannel is arranged around the polarizing protection ring in a circumferential direction. The inlet of the annular cooling microchannel is connected to the upper part of the annular cooling water cavity. The outlet of the annular cooling microchannel is connected to the cooling water outlet through the annular water collection tank at the bottom. Preferably, the outlet directions of the multiple water channels are evenly distributed along the circumference at 360°, and the angle between each outlet and the vertical direction is 5°-15°, all of which are inclined inward toward the central axis of the nozzle.

[0008] Preferably, the annular cooling water cavity is provided with a spiral flow guiding structure.

[0009] Preferably, the replaceable nozzle core is positioned by a self-centering conical surface and is detachably fixed to the nozzle mounting base by a locking nut.

[0010] Preferably, a black light-absorbing ceramic coating is attached to the conical surface of the inner hole of the polarizing protection ring using a micro-arc oxidation process.

[0011] Preferably, it also includes a temperature sensor and a scattered light sensor. The temperature sensor is installed on the outer wall of the polarization protection ring, and the scattered light sensor is installed on the side wall of the coupling cavity. Both are electrically connected to an external controller.

[0012] Preferably, it also includes a splash guard installed at the bottom of the housing.

[0013] Preferably, the anti-splash protective cover is conical, and its inner wall of the mirror surface forms an angle of 10°-30° with the vertical direction.

[0014] Preferably, the oleophobic coating of the anti-splash protective cover is a fluorosilane or a diamond-like carbon film.

[0015] Preferably, it also includes an optical window mounted on the top of the housing.

[0016] The long-life processing head device of the present invention, suitable for high-power water-guided laser processing, has the following beneficial effects: By separating the main water inlet channel from the annular cooling water chamber, the high-pressure working water and the low-pressure cooling water do not interfere with each other. This ensures both the stable high pressure required for the water-guided laser and low-pressure, high-flow-rate cooling, reducing system energy consumption and water quality requirements. The dual-chamber design decouples high-pressure water supply from low-pressure, high-flow-rate cooling, making it suitable for high-power continuous processing (≥200W).

[0017] The backpressure water outlet device uses a 360° multi-channel symmetrical oblique water jet converging technology to fully homogenize the water jet at the nozzle inlet, forming a laminar water jet with a finer diameter and more uniform velocity distribution, which significantly improves the coupling efficiency and transmission stability of the water-guided laser.

[0018] A polarizing protection ring is precisely positioned along the critical path of scattered light propagation. A high-absorption coating absorbs the scattered laser energy on-site, and a closed cooling loop is formed between the ring-shaped cooling microchannel and the ring-shaped cooling water chamber. Cooling water immediately removes heat, preventing downward heat conduction and protecting the dimensional stability of the underlying seals and structure. A temperature sensor monitors the ring temperature in real time and controls the cooling water flow, achieving closed-loop temperature control and reducing the temperature rise in the nozzle area by more than 60%.

[0019] As the last mechanical barrier, the anti-splash protection cover can intercept large particles of molten slag or abnormal rebounding objects, replacing the complex and disruptive "water curtain / air curtain" that interferes with the main jet. It effectively intercepts splashing particles and is easy to maintain.

[0020] The replaceable nozzle core, combined with the conical self-centering structure, enables quick and cost-effective replacement of vulnerable parts. The addition of a scattered light sensor and a temperature sensor gives the machining head intelligent monitoring capabilities, facilitating predictive maintenance. The overall structure is compact and easily integrated into existing water-guided laser machine tools. Attached Figure Description

[0021] Figure 1 This is an isometric three-dimensional structural diagram of a long-life processing head device suitable for high-power water-guided laser processing proposed in this invention; Figure 2 This is a cross-sectional schematic diagram of the structure of a long-life processing head device suitable for high-power water-guided laser processing proposed in this invention.

[0022] In the diagram: 1-Housing; 2-Optical window; 3-Coupled cavity; 4-High-pressure water inlet; 5-Main water inlet channel; 6-Backpressure water outlet device; 7-Nozzle mounting base; 8-Polarizing protection ring; 9-Cooling water inlet; 10-Annular cooling water cavity; 11-Cooling microchannel; 12-Cooling water outlet; 13-Bottom annular water collection tank; 14-Replaceable nozzle core; 15-Scattered light sensor; 16-Temperature sensor; 17-Anti-splash protection cover; 18-Water jet; 19-Workpiece. Detailed Implementation

[0023] like Figure 1 and Figure 2 As shown, Figure 1 This is an isometric three-dimensional structural diagram of a long-life processing head device suitable for high-power water-guided laser processing proposed in this invention; Figure 2 This is a cross-sectional schematic diagram of the structure of a long-life processing head device suitable for high-power water-guided laser processing proposed in this invention.

[0024] The purpose of this invention is to provide a long-life water-guided laser processing head device suitable for high power. Through the synergy of independent upper and lower dual water cavities, back pressure water outlet device, active cooling polarization protection ring and anti-splash protection cover, it achieves multiple controls on scattered light heat, splashed powder and heat accumulation, significantly improving the lifespan of high-power continuous operation.

[0025] Reference Figure 1 and Figure 2 The present invention proposes a water-guided laser processing head suitable for high power, comprising: a housing 1, an optical window 2, a coupling cavity 3, a main water inlet channel 5, a high-pressure water inlet 4, a back pressure water outlet device 6, a nozzle mounting base 7, a replaceable nozzle core 14, an independent annular cooling water cavity 10, a polarizing protection ring 8, an anti-splash protection cover 17, a scattered light sensor 15, and a temperature sensor 16.

[0026] The housing 1 of the processing head is made of 316L stainless steel and is generally stepped cylindrical. A sapphire optical window 2, 20mm in diameter and 3mm thick, is encapsulated within the top window seat of the housing 1 by a fluororubber O-ring and a pressure ring. Below the optical window 2 is a coupling cavity 3, 80mm long and 10mm in diameter. A main water inlet channel 5, a 4mm diameter oblique hole, is located on the upper side wall of the coupling cavity 3 and connects to a high-pressure water inlet 4. The operating water pressure is 250 bar.

[0027] The housing 1 contains two independent water chambers: the upper coupling chamber 3 is connected to the main water inlet channel 5, which is connected to an external high-pressure water source via a high-pressure water inlet 4, with a pressure range of 100~500 bar, to provide high-pressure working water for the coupling chamber 3; the lower annular cooling water chamber 10 is a low-pressure cooling water chamber with a pressure range of 1~10 bar, connected to an external low-pressure water source via a cooling water inlet 9. The two water sources are completely isolated to prevent high-pressure water leakage into the low-pressure chamber. The low-pressure chamber can be circulated with high-flow, low-cost cooling water that can be filtered, and is specifically responsible for indirect cooling of the lower part of the housing, the polarizing protection ring, and the nozzle mounting base.

[0028] A backpressure outlet device 6 is installed at the outlet of the main inlet channel 5. After high-pressure water enters the coupling cavity 3 from the main inlet channel 5, it first flows through the backpressure outlet device 6. The backpressure outlet device 6 has a ring structure with multiple symmetrical obliquely converging water channels distributed in a ring. The outlet directions of the channels are evenly distributed along the circumference at 360°, and the angle between each outlet and the vertical direction is 5°-15°, preferably 10°, all deflected inward toward the central axis of the nozzle. After the high-pressure water is ejected from each outlet simultaneously, it generates a radially inward converging flow in the cavity, forming a uniform contracting flow field, and finally converges into a thin, stable, and uniform water jet at the central inlet of the nozzle mounting seat 7. This water channel design, which sprays obliquely downward from 360° and finally converges at a point from different directions, introduces high-pressure water through symmetrical multi-channels, ensuring that the water flow is fully homogenized before entering the nozzle. Studies have shown that the coupling cavity with a symmetrical channel structure can achieve a uniform distribution of the flow field within the thin water layer coupling cavity and ensure a stable output of the water jet. Simultaneously, the water flow converges inward from a 360° circumference, resulting in a more uniform velocity distribution across the water jet cross-section. This eliminates the flow deviation and eddies caused by unilateral water inflow, creating a finer-diameter water jet with better laminar flow characteristics at the nozzle outlet. This effectively improves the coupling efficiency and transmission stability of the water-guided laser. Measurements show that after adopting this backpressure water outlet device 6, the laminar stability length of the water jet at the nozzle outlet increased from approximately 80 mm in the ordinary structure to over 120 mm, the water jet diameter decreased from 0.3 mm to 0.2 mm, and the coupling efficiency increased from approximately 65% ​​to over 85%.

[0029] The bottom of the back pressure water outlet device 6 is provided with a central water outlet that communicates with the nozzle mounting seat 7. The water jet that has been gathered flows out through this outlet and is sprayed downwards.

[0030] An active-cooled polarizing protection ring 8 is coaxially fixed on the step inside the housing between the coupling cavity 3 and the nozzle mounting seat 7, located 5-10 mm below the horizontal plane of the main water inlet channel 5 outlet. This position is the necessary path for scattered laser light to propagate downwards from the coupling cavity. Scattered laser light mainly originates from stray light radiation generated when the laser beam passes through the optical window and the coupling cavity. The most concentrated scattering area is precisely the free space between the laser beam from the optical window and the nozzle inlet. Therefore, installing the polarizing protection ring here can intercept most of the downward-propagating scattered light.

[0031] Scattered laser light mainly originates from stray light radiation generated when the laser beam passes through the optical window and coupling cavity due to scattering on the surface of optical elements, fluctuations in the water jet inlet, or changes in the laser mode. The most concentrated scattering area is the free space between the laser beam and the nozzle inlet. Therefore, installing a polarization protection ring here can effectively intercept most of the downward-propagating scattered light.

[0032] The nozzle mounting base 7 is bolted to the lower flange of the coupling cavity 3, and a replaceable nozzle core 14 is installed in its central hole. The nozzle core 14 is made of polycrystalline diamond (PCD), and its inner hole is divided into three sections: an inlet cone angle of 60°, a straight hole section with a diameter of 0.2 mm, and an outlet cone angle of 15°. The replaceable nozzle core 14 is fixed to the nozzle mounting base 7 by a self-centering conical fit and a locking nut, enabling quick replacement. The upper end of the nozzle core 14 fits against the 60° inner cone surface of the nozzle mounting base 7 through a 60° outer cone surface, and the lower part is screwed with a locking nut to ensure coaxiality better than 5μm. The laser beam enters the coupling cavity 3 through the optical window 2, is focused about 1 mm above the inlet plane of the nozzle core 14, and then efficiently couples into the water jet 18, and is transmitted to the workpiece 20 by total internal reflection along the water jet 18. The control sequence is to first start the high-pressure water pump to form a stable water jet, and then turn on the laser.

[0033] The polarizing protection ring 8 is made of T2 copper, with an inner diameter of 12mm, an outer diameter of 20mm, and an axial length of 12mm. It is press-fitted onto the inner hole step of the housing 1. The upper end of its inner hole is machined with a 45° chamfered conical surface. A 30μm thick black light-absorbing ceramic coating is attached to the conical surface using a micro-arc oxidation process, achieving an absorption rate of 95% for a wavelength of 532nm. Inside the polarizing protection ring 8, an annular cooling microchannel 11 is formed along the circumference, with a cross-sectional dimension of 1.5mm wide × 2mm high.

[0034] The polarizing protection ring 8 has an annular cooling microchannel 11 that communicates with the annular cooling water cavity 10. The annular cooling microchannel 11 is located inside the ring body of the polarizing protection ring 8 and is arranged around the circumference. Its inlet is connected to the upper part of the annular cooling water cavity 10, and its outlet is connected to the bottom annular water collection tank 13.

[0035] After entering the annular cooling water chamber 10 from the cooling water inlet 9, the cooling water is diverted from the inlet of the annular cooling microchannel 11 at the top into the polarizing protection ring, flows along the annular flow channel surrounding the chamber, uniformly cools the polarizing protection ring, then flows into the bottom annular water collection tank 13 at the bottom, and finally is discharged from the cooling water outlet 12.

[0036] The annular cooling water cavity 10 also features a spiral flow guiding structure, causing the cooling water to flow in a circumferential spiral pattern within the cavity, uniformly cooling the lower wall of the housing and the nozzle mounting base. The annular cooling microchannel 11 is interconnected with the annular cooling water cavity 10, forming a unified closed cooling circuit. After the polarizing protection ring absorbs the scattered laser light and converts it into heat, the heat is conducted through the ring to the cooling water in the annular cooling microchannel 11, where it is immediately carried away, preventing the heat from being conducted downwards to the nozzle seal.

[0037] The annular cooling water chamber 10 is a rectangular annular groove, 15mm wide and 8mm high, with a sealing plate welded to the outside to form a sealed cavity. The annular cooling water chamber 10 is connected to a 5-bar low-pressure circulating water system through the cooling water inlet 9. After the low-pressure cooling water enters the annular cooling water chamber 10, one path flows circumferentially along the spiral guide structure inside the chamber, uniformly cooling the lower wall of the shell and the nozzle mounting seat; the other path enters the annular cooling microchannel 11 of the polarizing protection ring 8 from the upper part of the annular cooling water chamber 10, flows along the channel surrounding the polarizing protection ring, uniformly cooling the ring, and then flows from the lower end of the channel into the bottom annular water collection tank 13, and finally returns to the circulation unit from the cooling water outlet 12.

[0038] The temperature sensor 16, a surface-mount Pt100, is mounted flush against the center of the outer wall of the polarization protection ring 8 to monitor the ring temperature in real time. When the temperature exceeds 80°C, the signal is transmitted to the controller, which automatically adjusts the cooling water flow to maintain a stable temperature. The entire cooling circuit is a closed-loop active circulation system, with no water spray directed towards the processing area.

[0039] A splash guard 17 is installed, made of stainless steel 304 / 316L or titanium alloy TC4, with an overall wall thickness of 1.5mm. The guard has an inverted conical cross-section, with an upper inner diameter of 45mm, a lower inner diameter of 55mm, and a height of 25mm. The lower end face is 3mm lower than the nozzle core 14 outlet. The inner surface of the splash guard 17 is diamond-machined to achieve a mirror finish with Ra≤0.1μm and is coated with a super oleophobic and easy-to-clean coating such as fluorosilane or a nano oleophobic coating with an oil contact angle >110°.

[0040] The anti-splash protection cover 17 is connected to the bottom of the housing 1 via a fine-threaded or bayonet structure, completely surrounding the outlet of the replaceable nozzle core 14. It is a downwardly flared cone shape, with its lower end face 1-5 mm below the nozzle outlet. The anti-splash protection cover 17 effectively blocks high-speed molten slag and powder particles rebounding from the workpiece 20, preventing them from splashing upwards to the optical window and coupling cavity. Its mirror-like inner wall allows impacting particles to change direction, falling back into the processing area and being quickly carried away by the water jet 18. Simultaneously, the coating surface has anti-adhesion properties, making it difficult for particles to adhere. The cover can be quickly disassembled by hand, and regular rinsing or wiping restores its cleanliness, resulting in extremely low maintenance costs. Furthermore, the anti-splash protection cover 17 achieves natural cooling through metal-to-metal heat conduction and water mist in the processing area. No additional water curtain or air curtain is required throughout the process; it relies entirely on the physical barrier and the scouring ability of the water jet itself, making its structure simple and reliable.

[0041] The temperature / scattered light detection elements include a patch-type Pt100 thermocouple temperature sensor 16 and a photodiode scattered light sensor 15. The scattered light sensor 15 is mounted at the quartz window on the side wall of the coupling cavity 3 to detect the intensity of scattered light within the cavity in real time; the temperature sensor 16 is attached to the outer wall of the polarization protection ring 8 to monitor the ring temperature in real time. Both are electrically connected to an external controller. When the detected temperature exceeds a set threshold or the scattered light intensity increases abnormally, a signal is transmitted to the controller. When the detected temperature exceeds 80℃ or the scattered light intensity increases abnormally, the controller automatically reduces the laser power or triggers an alarm, thus achieving predictive maintenance.

[0042] After 20 hours of continuous processing of 250W, 532nm stainless steel workpieces, the outer wall temperature of the polarizing protection ring 8 remained stable below 65℃. Closed-loop temperature control kept the ring temperature within the set range, the nozzle mounting seat 7 temperature was below 45℃, and there was no significant contamination of the optical window and nozzle core. The processing head did not require machine downtime for cleaning. Compared to traditional structures that do not employ active cooling polarizing rings and purely physical splash guards, the lifespan under the same operating conditions was extended from approximately 2 hours to over 20 hours.

[0043] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A long-life water-guided laser processing head device suitable for high-power lasers, characterized in that, include: Housing (1), coupling cavity (3), high-pressure water inlet (4), main water inlet channel (5), back pressure water outlet device (6), nozzle mounting base (7), replaceable nozzle core (14); The shell (1) has two independent water chambers inside; the coupling chamber (3) located at the top is connected to the main water inlet channel (5), the main water inlet channel (5) is connected to the external high-pressure water source through the high-pressure water inlet (4), and the annular cooling water chamber (10) located at the bottom is connected to the external low-pressure water source through the cooling water inlet (9); A back pressure outlet device (6) is provided at the outlet of the main water inlet channel (5). The back pressure outlet device (6) has multiple symmetrical oblique converging water channels distributed in a ring. The bottom of the back pressure outlet device (6) is provided with an outlet that communicates with the nozzle mounting base (7). The replaceable nozzle core (14) is installed on the nozzle mounting base (7). A polarizing protection ring (8) is coaxially fixed between the coupling cavity (3) and the nozzle mounting seat (7). An annular cooling microchannel (11) is arranged around the polarizing protection ring (8) in a circumferential direction. The inlet of the annular cooling microchannel (11) is connected to the upper part of the annular cooling water cavity (10). The outlet of the annular cooling microchannel (11) is connected to the cooling water outlet (12) through the annular water collection tank (13) at the bottom.

2. The device for a high-power, long-life water-guided laser processing head according to claim 1, characterized in that, The outlets of the multiple water channels are evenly distributed along the circumference at 360°. Each outlet has an angle of 5°-15° with the vertical direction and is tilted inward toward the central axis of the nozzle.

3. The device for high-power, long-life water-guided laser processing head according to claim 1, characterized in that, The annular cooling water chamber (10) is equipped with a spiral flow guiding structure.

4. The device for high-power, long-life water-guided laser processing head according to claim 1, characterized in that, The replaceable nozzle core (14) is positioned by a conical self-centering mechanism and is detachably fixed to the nozzle mounting base (7) by a locking nut.

5. The device for a high-power, long-life water-guided laser processing head according to claim 1, characterized in that, The inner hole of the polarizing protection ring (8) has a black light-absorbing ceramic coating attached to it using a micro-arc oxidation process.

6. The device for a high-power, long-life water-guided laser processing head according to claim 1, characterized in that, It also includes a temperature sensor (16) and a diffuse light sensor (15). The temperature sensor (16) is installed on the outer wall of the polarization protection ring (8), and the diffuse light sensor (15) is installed on the side wall of the coupling cavity (3). Both are electrically connected to the external controller.

7. The device for a high-power, long-life water-guided laser processing head according to any one of claims 1-6, characterized in that, It also includes a splash guard (17) which is installed at the bottom of the housing (1).

8. The device for a high-power, long-life water-guided laser processing head according to claim 7, characterized in that, The anti-splash protection cover (17) is conical, and its inner wall of the mirror surface forms an angle of 10°-30° with the vertical direction.

9. The device for a high-power, long-life water-guided laser processing head according to claim 7, characterized in that, The oleophobic coating of the anti-splash protective cover (17) is fluorosilane or diamond-like carbon film.

10. The device for a high-power, long-life water-guided laser processing head according to any one of claims 1-6, characterized in that, It also includes an optical window (2), which is mounted on top of the housing (1).

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