Method for improving titanium alloy picosecond laser drilling quality

Abstract

The invention provides a method for improving titanium alloy picosecond laser drilling quality, which belongs to the technical field of laser processing, and comprises the following steps: S1, pretreating a titanium alloy material to be processed and tested, and fixing the titanium alloy material on a workbench; s2, a machining position is positioned, and laser parameters and paths required by machining are set; and S3, a common scanning number value is set, and machining is started. And S4, observing the small hole opening condition, if the small hole is opened, reducing the scanning times, and if the small hole is not opened, otherwise. And repeatedly processing and adjusting. And S5, a new titanium alloy material is replaced, the formal machining position is positioned, and laser parameters and the number of scanning times for just getting through are set. By means of the method, the proper scanning frequency is determined, energy absorbed by the material can just meet the punching requirement, excessive accumulation of the energy is avoided, and therefore splash is reduced, and the thickness of an accumulation layer is reduced.

Description

Technical Field

[0001] The present invention relates to the field of laser processing technology, and in particular to a method for improving the quality of picosecond laser drilling of titanium alloys. Background Art

[0002] Titanium alloys are widely used in high-end equipment manufacturing fields such as aerospace and medical devices due to their excellent mechanical properties and corrosion resistance. Due to the high hardness and low thermal conductivity of titanium alloys, traditional mechanical processing is difficult to meet the high-precision requirements of microholes. Laser drilling, as an efficient, non-contact, and precise processing technology, has become an important means of titanium alloy microhole processing. According to the size of the laser pulse width, it can be divided into three types: long pulse, short pulse, and ultrashort pulse. Generally speaking, long and short pulses are divided by the laser pulse width of 100ns. The pulse of a short pulse laser is less than 100ns, while the opposite is true for a long pulse laser. The pulse width of a picosecond laser is extremely short and belongs to an ultrashort pulse. During picosecond laser processing, the melting and cooling phenomenon occurs, and the detached materials on the surface of the workpiece form too much spatter residue, which cannot meet the processing quality requirements. Therefore, it is necessary to improve the quality method of titanium alloy picosecond laser drilling in the existing technology to solve the above problems. Summary of the Invention

[0003] In response to the problems existing in the prior art, the present invention provides a method for improving the quality of picosecond laser drilling of titanium alloys, which can ensure that the energy absorbed by the material can just meet the drilling requirements, avoid excessive energy accumulation, thereby reducing the generation of spatter and reducing the thickness of the accumulation layer.

[0004] To solve the above technical problems, the present invention provides the following technical solution: a method for improving the quality of picosecond laser drilling of titanium alloy, comprising the following steps:

[0005] S1. Pre-treat the titanium alloy TC4 material to be processed and fixed on the workbench.

[0006] S2. Locate the processing hole position, set the processing laser parameters, and the scanning path of the laser beam.

[0007] S3. Preset the number of processing scans and use the laser to perform laser scanning and drilling on the processing holes.

[0008] S4. Observe the hole punching situation based on the number of processing scans. If the hole is punched through, reduce the number of scans. If the hole is not punched through, increase the number of scans. Repeat the processing test until the number of scans that can just punch through the hole is obtained.

[0009] S5. Carry out formal material laser processing, locate the formal processing position, set the laser parameters and the number of scans that just make a breakthrough, and carry out batch processing of small holes with the same parameters.

[0010] Furthermore, in the aforementioned step S1, the titanium alloy TC4 material to be processed and tested is pretreated, including polishing using sandpaper, grinding wheel or abrasive sandblasting until the oxide layer is completely removed and the surface presents a metallic luster, and then the polished titanium alloy TC4 material is placed in anhydrous ethanol, and finally cleaned by an ultrasonic cleaning machine.

[0011] Furthermore, in the aforementioned step S1, the titanium alloy TC4 material to be processed and tested is fixed using positioning pins.

[0012] Furthermore, in the aforementioned step S2, setting the processing laser parameters includes setting the laser power, scanning speed, and defocusing amount.

[0013] Furthermore, in the aforementioned step S2, a CCD camera is used to locate the hole processing position.

[0014] Furthermore, the aforementioned laser path sets the laser scanning path as a concentric circle scanning path.

[0015] Furthermore, the aforementioned step S3 includes turning on the laser power supply, preheating to a stable state, and then performing processing.

[0016] Furthermore, in the aforementioned step S4, the observation of whether the small hole is opened is specifically carried out by: physical observation method, observing the material against light to see whether there is light passing through.

[0017] Compared with the prior art, the beneficial technical effects of the present invention using the above technical solution are as follows:

[0018] With traditional laser drilling, excessive laser energy accumulates on the material surface. Each scan causes the material to absorb energy and gradually heat up, melt, or even vaporize. Excessive scans can cause the material to absorb far more energy than required to remove it. This excess energy causes a large amount of melted material to be expelled from the hole as spatter, forming a thick layer of material around the hole. Determining the appropriate number of scans ensures that the material absorbs just enough energy to punch the hole, avoiding excessive energy accumulation, reducing spatter and the thickness of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the present invention.

[0020] Figure 2 This is a schematic diagram of laser drilling.

[0021] Figure 3 This is a graph of different scan times in the example.

[0022] In the figure, 1-laser, 2-laser beam, 3-4 scanning path, 4-titanium alloy TC4 material. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0024] Various aspects of the present invention are described herein with reference to the accompanying drawings, which show a number of illustrative embodiments. The embodiments of the present invention are not limited to those described in the accompanying drawings. It should be understood that the present invention can be implemented by any of the various concepts and embodiments described above, as well as the concepts and implementations described in detail below, because the concepts and embodiments disclosed herein are not limited to any particular implementation. In addition, some aspects disclosed herein may be used alone or in any appropriate combination with other aspects disclosed herein.

[0025] refer to Figure 1 and Figure 2 The embodiment of the present invention provides a method for improving the quality of picosecond laser drilling of titanium alloy, comprising the following steps:

[0026] S1. Pre-treat the titanium alloy TC4 material 4 to be processed and tested, and fix it on a workbench.

[0027] Preferably, in the embodiment, the thickness of the titanium alloy TC4 material 4 is 0.5 mm. In order to reduce the absorption effect of the high roughness surface of the titanium alloy on the laser beam energy during processing, it is necessary to use different types of metallographic sandpaper to grind the surface. Mechanical polishing is performed by sandpaper, grinding wheel or abrasive sandblasting. The alloy surface can be polished with sandpaper with a particle size of 240 mesh and 120 mesh, and the oxide layer is completely removed and the surface presents a metallic luster. After the first and second steps of polishing, it is placed in anhydrous ethanol and then placed in an ultrasonic cleaning machine for the next step of cleaning. The cleaned titanium alloy material is clamped on a fixture to keep the material level.

[0028] S2, locate the processing hole position, set the processing laser parameters, and the scanning path 3 of the laser beam 2.

[0029] Specifically, first use a CCD camera to locate the hole processing position and adjust the position of the workpiece to be processed so that the laser head is facing the processing area, and set the laser parameters other than the number of scans on the laser, such as laser power, scanning speed, defocus, etc. A concentric circle laser drilling path is set, because when the innermost concentric circle of the microhole is punched through, the subsequent concentric circle elements are processed, and the spatter and slag generated during the processing can be easily removed from the bottom of the processed microhole, thereby improving the processing efficiency and quality during the subsequent picosecond laser action process. In the embodiment, the laser parameters are: scanning speed 25mm / s, scanning power 80%, and defocus of 0. The drilling path is: concentric circle scanning, the maximum circle is 0.3mm in diameter, and the diameter of each circle is 0.01mm apart.

[0030] S3. Preset the number of processing scans and use laser 1 to perform laser scanning and drilling on the processing hole. Specifically, first turn on the laser power supply, preheat to a stable state, then set the number of scans to 50 times and start processing.

[0031] S4. Observe the hole punching situation according to the number of processing scans. If the hole is punched through, reduce the number of scans. If the hole is not punched through, increase the number of scans. Repeat the processing test until the number of scans that can just punch through the hole is obtained.

[0032] like Figure 3 As shown in the figure, during the specific operation, the number of scans was 50 and the small hole was opened. The number of scans was adjusted to 40 and the small hole was opened. The number of scans was adjusted to 30 and the small hole was opened. The number of scans was adjusted to 20 and the small hole was opened. The number of scans was adjusted to 9 and the small hole was opened. The number of scans was adjusted to 8 and the small hole was not opened.

[0033] S5, perform formal laser processing of the material, locate the formal processing position, set the laser parameters and the number of scans required to just get through, and perform batch processing of small holes with the same parameters. In the embodiment, the laser parameters and the number of scans required to just get through are set to 9 times.

[0034] The small hole processed in step S4 is selected to detect the material after laser processing, as shown in Table 1 below:

[0035] Table 1

[0036]

[0037] The results show that compared to holes punched with other scan times, the height of the melt accumulation layer for holes punched with scans just enough to punch through the hole is significantly lower than that of holes punched before the improvement. This is because laser energy accumulates excessively on the material surface. With each scan, the laser absorbs energy and gradually heats, melts, and even vaporizes the material. Excessive scans cause the material to absorb far more energy than required to remove it. This excess energy causes a large amount of molten material to be expelled from the hole in the form of spatter, forming a thick accumulation layer around the hole. Through precise calculations and experiments, the appropriate scan times were determined so that the material absorbs just enough energy to punch the hole, avoiding excessive energy accumulation, thereby reducing the generation of spatter and the thickness of the accumulation layer, effectively improving the drilling quality.

[0038] While the present invention has been described above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for improving the quality of picosecond laser drilling of titanium alloy, characterized in that: The following steps are involved: S1, pre-treating the titanium alloy TC4 material (4) to be processed and tested, and fixing it on a workbench; S2, locating the processing hole position, setting the processing laser parameters, and the scanning path (3) of the laser beam (2); S3, preset the number of processing scans, and use the laser (1) to perform laser scanning and drilling on the processing hole; S4. Observe the hole punching condition based on the number of processing scans. If the hole is punched through, reduce the number of scans. If the hole is not punched through, increase the number of scans. Repeat the processing test until the number of scans that can just punch through the hole is obtained. S5. Carry out formal material laser processing, locate the formal processing position, set the laser parameters and the number of scans that just make a breakthrough, and carry out batch processing of small holes with the same parameters.

2. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: Step S1 pre-treats the titanium alloy TC4 material (4) to be processed and tested, including polishing it using sandpaper, a grinding wheel or abrasive blasting until the oxide layer is completely removed and the surface presents a metallic luster, then placing the polished titanium alloy TC4 material in anhydrous ethanol, and finally cleaning it with an ultrasonic cleaning machine.

3. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: In step S1, a titanium alloy TC4 material (4) to be processed and tested is fixed by a positioning pin.

4. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: In step S2, setting the processing laser parameters includes setting the laser power, scanning speed, and defocusing amount.

5. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: In step S2, a CCD camera is used to locate the hole processing position.

6. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: In step S2, the laser path sets the laser scanning path (3) to a concentric circle scanning path.

7. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: Step S3 includes turning on the laser power supply, preheating to a stable state, and then performing processing.

8. The method for improving the quality of picosecond laser drilling of titanium alloy according to claim 1, characterized in that: In step S4, the hole opening condition is observed by physical observation method, in which the material is held up to light to see whether there is light passing through.

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