Special-shaped hole etching method based on water-guided laser

Abstract

The invention discloses a special-shaped hole etching method based on water-guided laser, and the method comprises the following steps: S1, extracting a special-shaped hole model, layering the special-shaped hole model in layering software, and obtaining N model sheet layers, N being a positive integer greater than or equal to 3; s2, in filling software, alternately performing transverse filling and vertical filling from the first model slice layer to the Nth model slice layer; s3, sequentially arranging the filled model slice layers according to the sequence from the first model slice layer to the Nth model slice layer to obtain an etching sequence; and S4, according to the etching sequence, a water-jet guided laser system is adopted to conduct layer-by-layer etching on the workpiece to be machined, and a special-shaped hole identical to the special-shaped hole model is formed. According to the special-shaped hole etching method provided by the invention, the bottom morphology is flat after each layer of etching is completed, high and low points are avoided, and the special-shaped hole processing quality and processing precision of hard and brittle materials such as CMC ceramic matrix composite materials are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser processing, and in particular relates to a method for etching special-shaped holes based on water-guided laser. Background Art

[0002] Special-shaped holes are common in mechanical manufacturing, aerospace, automotive industry, mold design and other fields. For example, the cooling holes on turbine blades can be special-shaped holes to improve heat dissipation efficiency. Or in electronic equipment, special-shaped holes are used for heat dissipation or connection. In addition, the development of 3D printing technology has also promoted the manufacture of holes of complex shapes. Traditional methods include drilling, milling, electrical discharge machining (EDM), etc., but for holes of complex shapes, more advanced processes are required. For example, laser cutting can be used for high-precision special-shaped hole processing, especially for hard materials. Electrochemical machining (ECM) is suitable for conductive materials and can process complex shapes without generating heat-affected zones.

[0003] Microjet laser technology is widely used in precision machining due to its clean, thermally stress-free, and narrow cutting paths. However, for machining ceramic matrix composites (CMCs, which have a high hardness approaching that of diamond), traditional milling / drilling tools have extremely short lifespans, are prone to microcracks, and reduce material fatigue life. Traditional dry lasers, whether infrared or green, are limited by the laser's focal depth and galvanometer scanning, making them incapable of machining deep, irregularly shaped holes. Water-guided laser technology allows for deep machining and reduces thermal damage, but it lacks hierarchical path planning and a systematic approach for machining complex, three-dimensional, irregularly shaped holes.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method for etching irregular holes based on water-guided laser. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for etching a special-shaped hole based on a water-guided laser, comprising the following steps:

[0007] S1. Extracting a special-shaped hole model, and layering the special-shaped hole model in a layering software to obtain N model layers, where N ≥ 3 and N is a positive integer; wherein the model layers include circular cross-section layers and special-shaped surface layers, and the central axes of the circular cross-section layers coincide with each other;

[0008] S2. In the filling software, each of the model slices is filled; the filling method includes horizontal filling and vertical filling perpendicular to the horizontal filling;

[0009] From the first model layer to the Nth model layer, the horizontal filling and the vertical filling are performed alternately, so that any two adjacent model layers are filled in different ways;

[0010] S3, arranging the filled model slices in order from the first model slice to the Nth model slice to obtain an etching sequence; wherein the first model slice is the irregular surface slice farthest from the circular cross-section slice layer, and the Nth model slice is the circular cross-section slice farthest from the irregular surface slice layer;

[0011] S4. According to the etching sequence, a water-guided laser system is used to etch the workpiece layer by layer to form a special-shaped hole identical to the special-shaped hole model on the workpiece.

[0012] In one embodiment of the present invention, in step S4, during the layer-by-layer etching process, the starting points of the etching procedures of the respective model slice layers are on the same straight line;

[0013] The same straight line coincides with an extension line of the central axis of each of the circular section layers of the special-shaped hole model.

[0014] In one embodiment of the present invention, the N model sheets have the same thickness, which is 0.1-0.4 mm.

[0015] In one embodiment of the present invention, the water-guided laser system includes a laser, a water pressurization system, and a coaxial gas supply device;

[0016] The laser uses a green nanosecond pulse laser with a wavelength of 532nm; the water pressure in the water boosting system is 50-200bar, and the resistivity of the pure water used is greater than 15ΩM / cm 3 ; The coaxial air supply device uses helium, and the flow rate of the helium is not less than 0.1L / min.

[0017] In one embodiment of the present invention, in step S2, the spacing of the filling lines used in the filling is not less than the diameter of the nozzle of the laser;

[0018] The spacing between the filling lines of the horizontal filling is the distance between two adjacent filling lines extending horizontally; and the spacing between the filling lines of the vertical filling is the distance between two adjacent filling lines extending vertically.

[0019] In one embodiment of the present invention, the diameter of the laser nozzle is 60 μm, and the spacing between the filling lines is 80 μm.

[0020] In one embodiment of the present invention, in step S1, the layered software is ug software;

[0021] In step S2, the filling software is CAD software.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The method for etching irregular holes provided by the present invention performs water-guided laser etching of a fixed depth by alternating horizontal and vertical filling layer by layer to achieve the processing of three-dimensional irregular holes. Flat feeding can be achieved during the processing process, and the bottom morphology of each layer after etching is smooth without high or low points.

[0024] 2. The present invention adopts a water-guided laser system, so that the heat generated during the processing is effectively cooled by water, the residue is effectively carried away, and the thermal impact is small. It overcomes the focal depth limitation and galvanometer defects of traditional laser processing, and the deepest etching depth can reach 7mm.

[0025] 3. The method provided by the present invention improves the processing quality of hard and brittle materials such as CMC ceramic matrix composites, avoids the tool wear and microcrack problems caused by traditional mechanical processing, and realizes high-precision processing of special-shaped holes.

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 1 is a schematic flow chart of a method for etching a special-shaped hole based on a water-guided laser according to an embodiment of the present invention;

[0028] Figure 2 It is a three-dimensional schematic diagram of each model layer of the special-shaped hole model in one embodiment of the present disclosure of the present invention;

[0029] Figure 3 1 is a top view of each model layer of the irregular-shaped hole model in one embodiment of the present disclosure;

[0030] Figure 4 1 is a schematic diagram of a transverse filling cross-section of a first model layer in one embodiment of the present disclosure of the present invention;

[0031] Figure 5 1 is a schematic diagram of a vertical cross-section of a second model layer in one embodiment of the present disclosure of the present invention;

[0032] Figure 6 It is a schematic exploded cross-sectional view of the first model layer to the fourth model layer in one embodiment of the present disclosure of the present invention.

[0033] Figure 7 It is a schematic diagram of water-guided laser etching of a workpiece to be processed in one embodiment of the present disclosure of the present invention.

[0034] Description of reference numerals:

[0035] 1-first model layer; 11-program starting point of the first model layer; 2-second model layer; 21-program starting point of the second model layer; 3-third model layer; 31-program starting point of the third model layer; 4-fourth model layer; 41-program starting point of the fourth model layer; 5-Nth model layer; 6-laser; 7-workpiece to be processed. DETAILED DESCRIPTION

[0036] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of a special-shaped hole etching method based on water-guided laser proposed in accordance with the present invention in combination with the accompanying drawings and specific embodiments.

[0037] The aforementioned and other technical contents, features, and effects of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.

[0038] It should be noted that, in this article, relational terms such as first and second are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined. Moreover, the terms "comprises", "comprising" or any other variants are intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements includes not only those elements, but also other elements that are not explicitly listed.

[0039] The embodiment of the present invention provides a method for etching special-shaped holes based on water-guided laser, which is used to form special-shaped holes on CMC ceramic matrix composite materials. Figure 1 、 Figure 2 and Figure 3 , including the following steps:

[0040] S1. Extract the irregular-shaped hole model and layer the irregular-shaped hole model in layering software to obtain N model slices, where N ≥ 3 and N is a positive integer. The model slices include circular slices with circular cross-sections and irregular-shaped slices with irregular cross-sections, and the central axes of the circular slices coincide. The cross-sections are the two layered surfaces of the model slices after layering.

[0041] For example, the circular cross-section layer can be a cylinder or a frustum of a cone.

[0042] In one example, the N model sheets have the same thickness, which is 0.1-0.4 mm. For example, the thickness of the model sheets is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, or 0.4 mm.

[0043] Preferably, the thickness of the model sheet is 0.15 mm.

[0044] Exemplarily, the layering software may be UG software. That is, the UG software first obtains the outer contour of the irregular hole model, and then divides the irregular hole model into a plurality of model layers of the same thickness in the UG software according to a preset layer thickness.

[0045] S2. In the filling software, fill each model layer; the filling methods include horizontal filling and vertical filling perpendicular to the horizontal filling. From the first model layer 1 to the Nth model layer 5, horizontal filling and vertical filling are performed alternately to make the filling methods of any two adjacent model layers different. In this way, by alternating horizontal filling and vertical filling, etching of a fixed depth is performed layer by layer to achieve the processing of three-dimensional special-shaped holes. Flat feeding can be achieved during the processing process, and the bottom morphology of each layer is flat after etching, and there will be no high or low points. It should be explained that the horizontal filling here is not necessarily in the horizontal direction, and accordingly, the vertical filling does not have to be perpendicular to the horizontal plane; the corresponding horizontal and vertical directions can be set according to the shape of each model layer after the special-shaped hole model is layered to ensure that the horizontal and vertical directions are perpendicular.

[0046] like Figure 4 The first model sheet 1 is shown as being filled laterally (the filling line extends laterally and still extends laterally after the end portion turns), so that when the water-guided laser etching is subsequently performed, Figure 4 The etching is performed in the lateral etching direction shown in FIG. The starting point of the etching process for the first model layer 1 is Figure 4 In the diagram, it is located below the first model sheet 1 ( Figure 2 In the diagram, it is located above the first model sheet layer 1). Figure 5The second model sheet 2 is shown as being vertically filled (the filling line extends vertically, and the vertical extension end is still extended vertically after turning), so that when the water-guided laser etching is subsequently performed, Figure 5 The etching is performed in the vertical etching direction shown in FIG. The starting point of the process for etching the second model layer 2 is Figure 5 In the schematic diagram, it is located below the second model sheet 2 (at Figure 2 In the diagram, it is located above the second model sheet layer 2).

[0047] In one example, in step S2, the spacing of the filling lines used for filling is not less than the diameter of the nozzle of the laser 6. The spacing of the filling lines for horizontal filling is the distance between two adjacent horizontally extending filling lines, such as Figure 4 The spacing of the vertical filling lines is the distance between two adjacent vertically extending filling lines, such as Figure 5 d2 shown in the figure.

[0048] Exemplarily, the filling software is CAD software. In the CAD software, fill lines are drawn for each model layer. The fill lines serve as paths for subsequent laser etching, ultimately obtaining CAD drawings corresponding to each model layer.

[0049] S3. Arrange the CAD drawings of the filled model layers in order from the first model layer 1 to the Nth model layer 5 to obtain an etching sequence; wherein the first model layer 1 is the special-shaped surface layer farthest from the circular cross-section layer, and the Nth model layer 5 is the circular cross-section layer farthest from the special-shaped surface layer.

[0050] S4. A water-guided laser system etches the workpiece 7 layer by layer according to the etching sequence, forming a shaped hole identical to the shaped hole model on the workpiece 7. In this step, the heat generated during the water-guided laser processing is effectively cooled by the water, effectively removing the residue and minimizing the thermal impact. The etched depth of the resulting shaped hole reaches up to 7 mm.

[0051] For example, when a water-guided laser system is used to etch the workpiece 7 layer by layer, the angle of the workpiece 7 can be adjusted to match the angle of the special-shaped hole model, and an appropriate processing position can be selected to perform etching layer by layer until all layers are processed.

[0052] For example, in step S4, during the layer-by-layer etching process, the starting points for etching each model layer are on the same straight line. This same straight line coincides with the extension line of the central axis of each circular cross-section layer of the irregular hole model. In other words, when etching a model layer with a circular cross-section, the starting point of the etching program for each model layer is the center of the circular cross-section corresponding to the model layer; when etching a model layer with an irregular surface, the starting point of the etching program for each model layer is located on the extension line of the central axis of the model layer with the circular cross-section. In this way, the layered processing strategy based on the central axis of each irregular surface layer as the reference positioning effectively solves the inter-layer alignment problem in irregular hole processing.

[0053] For example, in step S4, the water-guided laser system includes a laser 6, a water pressurization system, and a coaxial air supply device. The laser 6 uses a green nanosecond pulse laser with a wavelength of 532nm; the water pressure in the water pressurization system is 50-200bar, and the resistivity of the pure water used is greater than 15ΩM / cm. 3 The coaxial gas supply device uses helium, with a flow rate of no less than 0.1 L / min. This implementation solves the technical issues of material removal accuracy and machining environment control during the machining of irregular-shaped holes by combining a specific wavelength laser with precise fluid parameters.

[0054] For example, the nozzle diameter of laser 6 is 60 μm, and the spacing of the fill lines is 80 μm. Thus, using a 532 nm green nanosecond pulsed laser, a 60 μm nozzle, and a water pressure of 50-200 bar, a process of alternating horizontal and vertical filling is used to achieve layer-by-layer etching of three-dimensional irregularly shaped holes. After each layer is etched, the bottom morphology is smooth, with no peaks or valleys, and the etching depth is relatively deep.

[0055] The following describes the water-guided laser-based irregular-shaped hole etching method provided by the present invention in detail, using specific examples. In the following examples, cooling holes are formed on a turbine blade made of a ceramic matrix composite (CMC) by water-guided laser etching. The cooling holes (irregular-shaped holes) are composed of circular slices with circular cross-sections and irregular-shaped slices with irregular cross-sections, with the central axes of the circular slices coinciding. In this example, the circular slices are truncated cones.

[0056] S1. Model extraction layer

[0057] See also Figure 2 After the special-shaped hole model is extracted, it is layered using UG software and divided into 50 model layers with an interval of 0.15 mm per layer. The total depth of the special-shaped hole model is 7.5 mm.

[0058] S2, filling

[0059] The irregular surface layer farthest from the circular surface layer is the first model layer 1, and the circular surface layer farthest from the irregular surface layer is the fiftieth model layer. Arrange the layers in the order of the first model layer 1 to the fiftieth model layer. In the CAD software, fill each model layer separately, such as Figure 4 and Figure 5 As shown, the filling method is to alternate between horizontal filling and vertical filling. For example, if the first model layer 1 is horizontally filled (such as Figure 4 (as shown), the second model layer 2 is filled vertically, the third model layer 3 is filled horizontally, and so on, alternating in sequence, so that any adjacent model layers have different filling methods. In this embodiment, the spacing d1 of the filling lines for the horizontal filling is ≥ 60 microns, and the spacing d2 of the filling lines for the vertical filling is ≥ 60 microns.

[0060] In CAD, the fill lines drawn for the model to be laser-processed serve as the etching paths for subsequent laser processing. This method uses alternating horizontal and vertical fills to ensure a smooth bottom surface with no peaks or valleys after each model layer is processed, providing a good foundation for machining the next model layer. This solves the problems of short tool life and microcracks associated with traditional milling / drilling, while also overcoming the technical bottleneck of electrochemical machining in producing complex 3D special-shaped holes.

[0061] S3, layer-by-layer arrangement

[0062] Arrange the CAD drawings obtained after the fill lines are drawn in the order of model layers 1 to 50 to generate an etching sequence. The subsequent water-guided laser etching program is then executed according to this etching sequence. In the water-guided laser etching program, the line connecting the starting points of the water-guided laser etching program for each model layer is a straight line; this straight line is an extension of the central axis of each circular section layer. In other words, the orthographic projections of the program starting points of each model layer onto the circular sections of each circular section layer coincide with each other, and are the center positions of each circular section.

[0063] S4. Select position for processing

[0064] like Figure 7 As shown, fix the workpiece 7 to be processed on the five-axis fixture, adjust the angle between the workpiece 7 and the horizontal line to 70 degrees, ensure that the central axis of the cylindrical segment of the irregular hole is consistent with the incident direction of the micro-jet of the water-guided laser, and make the placement angle of the workpiece 7 consistent with the angle of the irregular hole model. Then select the processing position, use the water-guided laser, and etch layer by layer in the order of the first model layer 1 to the fiftieth model layer to obtain the cooling hole (irregular hole). Figure 6The exploded cross-sectional view of the first model layer 1 to the fourth model layer 4 is shown. That is, in actual circumstances, the first model layer 1, the second model layer 2, the third model layer 3, and the fourth model layer 4 are arranged in an overlapping manner, and the program starting point 11 of the first model layer, the program starting point 21 of the second model layer, the program starting point 31 of the third model layer, and the program starting point 41 of the fourth model layer coincide with each other.

[0065] During water-guided laser processing, the parameters of the water-guided laser system were set as follows: Laser 6 used a green nanosecond pulsed laser with a rated power of 400W, a wavelength of 532nm, and a pulse frequency of 10kHz. The nozzle used a 60μm diameter nozzle, i.e., d = 0.06mm. The jet was set 12mm from the surface processing position of each model layer, the water pressure was set to 200bar, and the pure water resistivity was greater than 15ΩM / cm. 3 The coupling power at the jet processing position is 5-7W, and the helium flow rate is maintained at 0.1L / min. The total water-guided laser processing time is less than or equal to 30 minutes.

[0066] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for etching special-shaped holes based on water-guided laser, characterized in that: The following steps are involved: S1. Extracting a special-shaped hole model, and layering the special-shaped hole model in a layering software to obtain N model layers, where N ≥ 3 and N is a positive integer; wherein the model layers include circular cross-section layers and special-shaped surface layers, and the central axes of the circular cross-section layers coincide with each other; S2. In the filling software, each of the model slices is filled; the filling method includes horizontal filling and vertical filling perpendicular to the horizontal filling; From the first model layer to the Nth model layer, the horizontal filling and the vertical filling are performed alternately, so that any two adjacent model layers are filled in different ways; S3, arranging the filled model slices in order from the first model slice to the Nth model slice to obtain an etching sequence; wherein the first model slice is the irregular surface slice farthest from the circular cross-section slice layer, and the Nth model slice is the circular cross-section slice farthest from the irregular surface slice layer; S4. According to the etching sequence, a water-guided laser system is used to etch the workpiece layer by layer to form a special-shaped hole identical to the special-shaped hole model on the workpiece.

2. The method for etching special-shaped holes based on water-guided laser according to claim 1, characterized in that: In step S4, during the layer-by-layer etching process, the starting points of the etching procedures for each of the model layers are on the same straight line; The same straight line coincides with an extension line of the central axis of each of the circular section layers of the special-shaped hole model.

3. The method for etching special-shaped holes based on water-guided laser according to claim 1, characterized in that: The thickness of the N model sheets is the same, and the thickness of the model sheets is 0.1-0.4 mm.

4. The method for etching special-shaped holes based on water-guided laser according to claim 1, characterized in that: The water-guided laser system includes a laser, a water pressurization system and a coaxial air supply device; The laser uses a green nanosecond pulse laser with a wavelength of 532nm; the water pressure in the water boosting system is 50-200bar, and the resistivity of the pure water used is greater than 15ΩM / cm 3 ; The coaxial air supply device uses helium, and the flow rate of the helium is not less than 0.1L / min.

5. The method for etching special-shaped holes based on water-guided laser according to claim 4, characterized in that: In step S2, the spacing between the filling lines used in the filling is not less than the diameter of the laser nozzle; The spacing between the filling lines of the horizontal filling is the distance between two adjacent filling lines extending horizontally; and the spacing between the filling lines of the vertical filling is the distance between two adjacent filling lines extending vertically.

6. The method for etching special-shaped holes based on water-guided laser according to claim 5, characterized in that: The diameter of the laser nozzle is 60 μm, and the spacing between the filling lines is 80 μm.

7. The method for etching special-shaped holes based on water-guided laser according to claim 1, characterized in that: In step S1, the layered software is ug software; In step S2, the filling software is CAD software.

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