Laser drilling damage in-situ repair device, laser drilling device and laser drilling method

Abstract

The application discloses a kind of laser drilling damage in situ repair device, laser drilling device and laser drilling method, it includes: feeding unit, for when laser beam along several concentric circular trajectory, after completing laser scanning on workpiece, to the region that material has been etched on workpiece inside repair material is transported, with laser beam continues along circular trajectory, laser scanning is carried out on workpiece, to form hole structure.The application is by feeding unit and is transported to the vicinity of damage area repair material in real time, again using the heat conduction effect generated in the process of laser continues scanning and is fused softening repair material, and is in situ repaired to damage area.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, and in particular to a device for in-situ repair of laser hole-making damage, a laser hole-making device, and a laser hole-making method. Background Technology

[0002] Due to its outstanding advantages, it has become an advanced material widely used in the new generation of aerospace, automotive, new energy and other fields.

[0003] like Figure 1 As shown, a technique has been developed to create holes in workpieces (including carbon fiber reinforced thermoplastic composites (CFRTP) and other carbon fiber composites (CFRP) by scanning a laser beam L along a concentric circle trajectory. This technique mainly achieves material removal by absorbing laser energy in the workpiece material, thereby completing the hole creation. However, the thermal effect generated during laser action can cause thermal damage to the edge of the hole structure H and the material surface, resulting in a heat-affected zone S (i.e., the damaged area) that exposes the fibers. The surface of the cut hole wall will also have a certain degree of matrix material ablation, causing the fibers to protrude and lose protection, thus failing to exert the high strength performance of the material itself and reducing the overall mechanical properties of the material. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes an in-situ repair device, a laser drilling apparatus, and a laser drilling method for laser-induced hole formation damage. The device uses a feeding unit to deliver repair material to the vicinity of the damaged area in real time, and then utilizes the thermal conduction effect generated during the laser scanning process to melt and soften the repair material, thereby performing in-situ repair on the damaged area.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, an in-situ repair device for laser-induced hole drilling damage is provided, comprising:

[0007] The feeding unit is used to deliver repair material to the area on the workpiece where the material has been etched away after the laser beam has completed laser scanning on the workpiece along several concentric circular trajectories. At the same time, the laser beam continues to perform laser scanning on the workpiece along the circular trajectory to form a hole structure.

[0008] Preferably, the feeding unit includes:

[0009] The silo is used to store repair materials;

[0010] The first vibration unit is connected to the hopper to convey the repair material in the hopper downward through vibration.

[0011] A material conveying pipe that connects to the outlet of the silo and communicates with the interior of the silo;

[0012] The second vibration unit contacts the outer wall of the conveying pipe to convey the repair material in the conveying pipe along a predetermined conveying path through vibration.

[0013] A receiving turntable is set at the outlet of the conveying pipe to receive the repair material output from the outlet of the conveying pipe.

[0014] A turntable drive unit, which is connected to the receiving turntable, is used to drive the receiving turntable to rotate;

[0015] The ventilation duct has a notch on its outer circumference and a discharge port at the bottom facing the workpiece surface.

[0016] A gas source, which is connected to the ventilation pipe;

[0017] And a control unit, which is connected to one or more of the first vibration unit, the turntable drive unit, and the second vibration unit respectively, to control one or more of the first vibration unit, the turntable drive unit, and the second vibration unit to perform corresponding actions.

[0018] Preferably, the feeding unit further includes a screen, which is disposed inside the hopper for sieving the repair material.

[0019] Preferably, when the repair material is output through the discharge port, its conveying rate is 5-10 g / min.

[0020] Preferably, the feeding unit further includes:

[0021] The inner shell is hollow and a sealed environment, used to accommodate the notch of the receiving turntable, part / all of the material conveying pipes and the ventilation pipes.

[0022] Preferably, the feeding unit further includes:

[0023] The outer shell is hollow and enclosed, used to house the inner shell, some / all of the material conveying pipes, and the second vibration unit.

[0024] Preferably, the feeding unit further includes an infrared imaging unit, which is used to acquire infrared image information of the area where the repair material is located after the repair material is delivered to the surface of the workpiece in real time.

[0025] Preferably, the workpiece comprises a carbon fiber composite material.

[0026] On the other hand, a laser hole-making device is also provided, which includes: a laser, a beam expander, a first reflector, a working platform, the aforementioned powder feeding unit, a focusing field lens, a scanning head, a dynamic focusing axis, and a second reflector.

[0027] On the other hand, a laser hole-making method is also provided, which includes the following steps:

[0028] S1. Divide the workpiece into several layers to be cut along the thickness direction;

[0029] S2. The focal point of the focused laser beam falls on the current layer to be cut, and scans from the outside to the inside along the preset k concentric circle trajectories to form the corresponding circular scanning trajectory.

[0030] S3. The feeding unit continuously feeds powdered / granular repair material to the area on the workpiece where the material has been etched away; at the same time, the laser beam continues to scan the current layer to be cut along the remaining preset concentric circle trajectory until all scans are completed.

[0031] S5. Control the laser beam focus to decrease;

[0032] S6. Repeat steps S2-S4 above to complete the material removal on the next layer to be cut;

[0033] S7. Repeat step S6 above until the material of each layer to be cut is removed, and finally a hole structure is formed on the workpiece.

[0034] The beneficial effects of this invention are:

[0035] This invention delivers repair material to the vicinity of the damaged area in real time through a feeding unit. Then, the heat conduction effect generated during the laser scanning process melts and softens the repair material. After it cools and solidifies, it can cover the heat-affected zone, performing in-situ repair on damaged areas such as exposed fibers and matrix debonding, thus ensuring the mechanical properties of the material. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the damage area formed when a workpiece is scanned and drilled using a laser beam in the prior art;

[0037] Figure 2 This is a schematic diagram of the laser hole-making device in this invention;

[0038] Figure 3 This is a schematic diagram of the powder feeding unit in this invention;

[0039] Figure 4 This is a schematic diagram of the material receiving turntable in this invention;

[0040] Figure 5 A schematic diagram showing the division of the workpiece into layers to be cut;

[0041] Figure 6 This is a schematic diagram of a laser scanning on a workpiece, forming a concentric circular scanning trajectory. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this technical solution clearer, the following detailed description, in conjunction with specific embodiments, further illustrates this technical solution. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this technical solution.

[0043] Example 1:

[0044] like Figure 2 As shown, this embodiment provides an in-situ repair device for laser-induced hole drilling damage, which includes:

[0045] The feeding unit 7 is used to deliver powdered / granular repair material to the area where the material has been etched away on the workpiece 5 after the laser beam L completes laser scanning on the workpiece 5 along several concentric circular trajectories. At the same time, the laser beam L continues to perform laser scanning on the workpiece 100 along a circular trajectory to form a hole structure. During the continued scanning process, the repair material is melted by the thermal effect generated by the laser energy, so that the molten repair material can perform in-situ repair on the damaged area of ​​the workpiece 5.

[0046] In this embodiment, the repair material includes thermoplastic materials, specifically one or more of polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and polyether ketone ketone (PEKK), and the workpiece 100 includes carbon fiber composite material (CFRP), especially carbon fiber reinforced thermoplastic composite material (CFRTP).

[0047] Specifically, such as Figure 3 As shown, the feeding unit 7 includes:

[0048] hopper 21 is used to store powdered / granular repair materials;

[0049] A screen 22 is installed inside the hopper 21 to screen the powdered / granular repair material to remove large particle impurities.

[0050] The first vibration unit 23 is connected to the hopper 21 to convey the repair material in the hopper 21 downward through vibration.

[0051] The material conveying pipe 24 is connected to the outlet of the hopper 21 and communicates with the interior of the hopper 21; the repair material in the hopper 21 enters the material conveying pipe 24 under the action of the first vibration unit 23; in this embodiment, the material conveying pipe 24 is preferably a flexible hose, such as a PU steel wire smooth flexible hose, etc.

[0052] The second vibration unit 25 is in contact with the outer wall of the conveying pipe 24 so as to convey the repair material in the conveying pipe 24 along a predetermined conveying path through vibration.

[0053] A receiving turntable 26 is disposed at the outlet of the conveying pipe 24 to receive the repair material output from the outlet of the conveying pipe 24; further, in this embodiment, as... Figure 3-4 As shown, the receiving turntable 26 has a groove 261, which receives the repair material output from the discharge port of the conveying pipe 24. There are multiple grooves 261, which can be evenly spaced along the circumference of the receiving turntable 26.

[0054] The turntable drive unit 27 has a rotational power output shaft 271 connected to the receiving turntable 26, which is used to drive the receiving turntable 26 to rotate; in this embodiment, the turntable drive unit 27 includes a motor.

[0055] The ventilation pipe 28 has a notch on its outer circumference and a discharge port 281 facing the surface of the workpiece 5 at its bottom;

[0056] Gas source 29, which is connected to the ventilation pipe 28. In this embodiment, the gas source 29 is an inert gas, such as nitrogen, to avoid chemical reaction (such as oxidation reaction) with the repair material, which would affect the performance of the repair material.

[0057] and control unit 13, which is connected to one or more of the first vibration unit 23, turntable drive unit 27, and second vibration unit 25 respectively, so as to control one or more of the first vibration unit 23, turntable drive unit 27, and second vibration unit 25 to perform corresponding actions;

[0058] The turntable drive unit 27 drives the receiving turntable 26 to rotate, so that the repair material on the receiving turntable 26 enters the notch. The gas source 29 outputs gas, and the gas flow drives the repair material to move, and it is transported to the area on the surface of the workpiece 5 where the material has been etched away through the discharge port 281.

[0059] During operation, the control unit 13 controls the first vibration unit 23 to start working, so that the repair material in the hopper 21 falls evenly into the conveying pipe 24 after passing through the screen 22. The control unit 13 controls the second vibration device 27 to further ensure that the powder repair material falls onto the receiving turntable 26 through the conveying pipe 24 (preferably into the groove 261).

[0060] The control unit 13 controls the turntable drive unit 27 to rotate the receiving turntable 26, so that the repair material enters the notch of the ventilation pipe 28. The amount of repair material entering the notch of the ventilation pipe 28 per unit time can be controlled by the rotation speed of the receiving turntable 26, and the delivery amount of the repair material can be further controlled. For example, in the embodiment, when the repair material is output through the discharge port 281, its delivery amount is 5-10g / min.

[0061] The gas source 29 inputs inert gas into the ventilation pipe 28 so that the repair material can be moved by the gas flow and transported to a specific area of ​​the workpiece 5 through the discharge port 281.

[0062] Therefore, in this embodiment, the repair material is delivered to the vicinity of the heat-affected zone (i.e., the damaged area where the material has been etched away) in real time through the feeding unit. The heat conduction effect generated by the laser cutting hole-making process is used to melt and soften the repair material. After it cools and solidifies, it can cover the heat-affected zone and perform in-situ repair on damaged areas such as exposed fibers and debonded substrate.

[0063] Example 2:

[0064] The only difference between this embodiment and Embodiment 1 is that the laser-induced hole-forming damage in-situ repair device further includes:

[0065] The inner shell 32 is hollow and a sealed environment, used to accommodate the notch of the receiving turntable 26, part / all of the conveying pipe 24 and the ventilation pipe 28. This ensures that the process of conveying the repair material through the conveying pipe 24 and the receiving turntable 26 to the ventilation pipe 28 is carried out in a sealed environment, so as to avoid the outside air flow blowing away the repair material on the receiving turntable 26 and causing material loss.

[0066] The flow valve 31 is connected to the gas source 29 and the gas supply pipe 28 respectively, and is used to control the flow rate of the gas in the gas source 29.

[0067] The outer shell 30 is hollow and forms a sealed environment to accommodate the inner shell 32, part / all of the material conveying pipe 24, and the second vibration unit 25, thereby enhancing the sealing effect and improving the utilization rate of the repair material. In this embodiment, the inner wall of the outer shell 30 is connected to the inner shell 32.

[0068] In addition, there is an infrared imaging unit 8, which is connected to the control unit 13, and is used to acquire infrared image information of the area where the repair material is located after the repair material is delivered to the surface of the workpiece 5 in real time, so as to monitor the temperature of the repair area and the repair process, and provide real-time feedback on the entire damage repair process.

[0069] Example 3:

[0070] This embodiment provides a laser hole-making device, such as... Figure 2 As shown, it includes: a laser 1, a beam expander 2, a first reflector 3, a working platform 4, a powder feeding unit 7 as described in embodiment 1 or 2, a focusing field lens 9, a scanning head 10, a dynamic focusing axis 11, and a second reflector 12.

[0071] The workpiece 5 is placed on the work platform 4. The laser 1 has a power of 5-20W and is used to emit a laser beam. After the laser beam is expanded by the beam expander 2, it is reflected by the first reflector 3 and the second reflector 9 in sequence to enter the dynamic focusing axis 11 and the scanning head 10, and then focused on the surface of the workpiece 5 by the field focusing field lens 9.

[0072] The control unit 13 is also connected to the dynamic focusing axis 11 and the scanning head 10 to control the scanning head 10 to perform laser scanning on the workpiece 5 according to a circular trajectory, and to control the dynamic focusing axis 11 to control the laser beam focus to descend, thereby forming a hole structure on the workpiece 5.

[0073] Example 4:

[0074] This embodiment provides a laser hole-making method, which can be implemented by the laser hole-making damage in-situ repair device described in any one of Embodiments 1-2, and includes the following steps:

[0075] S1, such as Figure 5 As shown, the workpiece 5 is divided into several layers to be cut in the thickness direction, such as L1, L2, L3...Li, and the thickness of the layers to be cut can be the same or different.

[0076] S2. The focal point of the focused laser beam L falls on the current layer to be cut (such as the first layer to be cut), and scans sequentially from the outside to the inside along k preset concentric circular trajectories (k is a positive integer, with a value range of [2,7]) to form corresponding circular scanning trajectories C01, C02, C03.... (such as...). Figure 6 (as shown);

[0077] When adjacent circular scanning trajectories are formed, the material between two different circular scanning trajectories is etched away under thermal ablation to produce an annular groove of a certain depth. At this point, the hole wall damage is basically fixed.

[0078] S3. The feeding unit 8 continuously feeds powdered / granular repair material to the area on the workpiece 5 where the material has been etched away.

[0079] Meanwhile, the laser beam L continues to scan the current layer to be cut along the remaining preset concentric circle trajectory until all scans are completed. At this point, the feeding unit 8 stops the repair material feeding, and the material on the current layer to be cut is completely removed.

[0080] During the continued scanning process, since the location is far from the previously damaged hole wall, the impact on it is small, and the damaged area will not expand. Therefore, the heat conduction effect generated by the laser beam can be used to melt and soften the repair material during the continued scanning, so that it can be attached to the exposed heat-affected zone of the fiber and the area around the debonded matrix. After cooling and solidification, the in-situ repair of the damage caused by the hole making process can be achieved. In steps S2 and S4, the scanning speed of the laser beam is 500-1000 mm / s.

[0081] S5. Control the laser beam focus to decrease (e.g., decrease by 0.02-0.05mm);

[0082] S6. Repeat steps S2-S4 above to complete the material removal on the next layer to be cut;

[0083] During the etching process of the previous layer to be cut, there may be excess solidified repair material on the hole wall, which affects the material processing accuracy. When the laser focus decreases and begins to scan along the k concentric circles around the next layer to be cut, the laser beam can effectively remove the residual repair material on the hole wall to ensure the hole making accuracy.

[0084] S7. Repeat step S6 above until the material of each layer to be cut is removed, and finally a hole structure is formed on workpiece 5.

[0085] In summary, during the hole-making process, after the material in a certain area is etched away, the repair material is delivered to the vicinity of the damaged area in real time through a feeding unit. Then, the thermal conduction effect generated during the laser scanning process is used to melt and soften the repair material. After it cools and solidifies, it can cover the heat-affected zone, and perform in-situ repair on damaged areas such as exposed fibers and matrix debonding. This results in a final hole structure with no obvious exposed fibers, a smooth surface without protrusions, and eliminates obvious debonding and crack damage, thus ensuring the mechanical properties of the material.

[0086] The above content is only a preferred embodiment of the present invention. For those skilled in the art, many changes can be made in the specific implementation and application scope based on the ideas of the present invention. As long as these changes do not depart from the concept of the present invention, they all fall within the protection scope of this patent.

Claims

1. A laser drilling method using a laser drilling damage in-situ repair device, wherein the laser drilling damage in-situ repair device comprises: A feeding unit is used to deliver repair material to areas on the workpiece where the material has been etched away after the laser beam has completed laser scanning along several concentric circular trajectories on the workpiece, while simultaneously allowing the laser beam to continue laser scanning along the circular trajectory on the workpiece to form a hole structure; characterized in that the laser hole-making method includes the following steps: S1. Divide the workpiece into several layers to be cut along the thickness direction; S2. The focal point of the focused laser beam falls on the current layer to be cut, and scans from the outside to the inside along the preset k concentric circle trajectories to form the corresponding circular scanning trajectory. S3. The feeding unit continuously feeds powdered / granular repair material to the area on the workpiece where the material has been etched away; at the same time, the laser beam continues to scan the current layer to be cut along the remaining preset concentric circle trajectory until all scans are completed. S4. Control the laser beam focus to decrease; S5. Repeat steps S2-S4 above to complete the material removal on the next layer to be cut; S6. Repeat step S5 above until the material of each layer to be cut is removed, and finally a hole structure is formed on the workpiece.

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