CN115815836A - Method for processing expanded hole by millisecond long pulse laser - Google Patents

Abstract

The invention relates to a method for processing an expanded hole by millisecond long pulse laser, which is based on six-axis linkage numerical control machine tool control, is matched with millisecond long pulse laser, and is realized in a three-dimensional space in a precise cutting mode. The invention can realize one-step laser processing and forming, shorten the time for processing a single expansion hole and greatly improve the processing efficiency.

Description

A Method of Millisecond Long Pulse Laser Machining Expansion Hole

technical field

The invention belongs to the technical field of laser processing holes, in particular to a method for processing expanded holes with a millisecond long pulse laser.

Background technique

The expansion hole is composed of a circular straight cut-off section, a diffusion section and an expansion section. It has a good film cooling effect. Due to its special structure, it can be directly processed on the metal substrate before spraying, and it can also be equipped with thermal barrier coating. Layer processing has been applied to a certain type of aero-engine turbine blades.

At present, based on the function of rotating the two-dimensional CNC rotating laser processing head around the center of the tool, adjusting the incident angle of the laser to realize the processing of the diffusion section and the expansion section solves the problem of direct laser processing at one time, but the processing process is complicated and the processing efficiency is low. Based on the scanning galvanometer filling processing method, and using ultrafast pulse lasers such as femtoseconds and picoseconds to process expanded holes, it has greatly improved the resolution of obvious thermal defects, but the scanning preparation steps before processing are complicated and time-consuming. The processing time for a single hole is up to 150 seconds, the processing efficiency is too low and the cost is high.

Contents of the invention

In order to solve the above technical problems, the purpose of the present invention is to provide a method for millisecond long pulse laser processing expansion hole.

To achieve the above object, the present invention adopts the following technical solutions:

A method for millisecond long pulse laser machining expansion holes, characterized in that it comprises the following steps:

Step 1: Positioning, use the adaptive laser focal length of the CNC machine tool to focus the laser on the center of the hole to be processed on the surface, adjust the axis where the laser head is located to coincide with the axis of the expansion hole to be processed, and realize positioning initialization;

Step 2: Process the hole expansion section, enable the plane rotation of the CNC machine tool, rotate the processing plane to be perpendicular to the beam axis, move the laser focus to the center of the hole expansion section, and move the laser head alternately laterally along the centerline of the expansion section to both ends until On the end edge, the hole expansion section is processed with multiple single pulses during the movement;

Step 3: Focus the laser on the center of the hole to be processed on the surface of the hole diffusion section, and multiple continuous pulses penetrate the base metal layer, so that the metal oxide and metal splash generated by the subsequent scanning pass through the hole;

Step 4: Return the laser focus to the center of the hole to be processed on the surface of the hole diffusion section, and the laser head moves laterally along the centerline of the diffusion section to both ends alternately, and process the hole diffusion section with multiple single pulses during the movement;

Step 5: Return the laser focus to the center of the hole to be processed on the surface of the diffusion section, and use the pulsed laser to rotate and cut the straight section of the cylindrical hole to the set size.

Preferably, the millisecond long-pulse laser processing method for expanding holes is based on the six-axis linkage CNC machine tool control, matching the millisecond long-pulse laser, and the laser beam is always parallel to the axis of the special-shaped hole during the entire processing cycle.

Preferably, in the method of millisecond long pulse laser processing expansion hole, the laser hole making process layers and sequentially processes expansion section, diffusion section and circular straight closure section, and the pulse emitted by each layer is from the center of the hole type to the divergence angle The two ends are symmetrical, and the increase or decrease of energy determines the divergence angle of the diffusion section.

Preferably, the millisecond long pulse laser processing method for expanding holes does not have a thermal barrier coating on the surface of the workpiece.

Preferably, in the method for machining expanded holes with a millisecond long pulse laser, the surface of the workpiece contains a thermal barrier coating.

Preferably, the millisecond long-pulse laser processing method for expanding holes includes the structure of the expanded holes formed by millisecond long-pulse laser processing.

Preferably, in the method for millisecond long pulse laser machining expansion holes, the structure of the expansion hole structure from the inlet end to the outlet end includes a circular straight cut-off section, a diffuser section and an expansion section, wherein the circular straight cut-off section is Cylindrical through hole, which is tangent to the smooth transition at the end of the diffusion section, the diffusion section is in the shape of a fan, with semi-circular transitions on both ends; the expansion section is a bevel added to one side of the diffusion section, and the end edge is a circular arc transition structure .

By means of the above solution, the present invention has at least the following advantages:

The invention adopts one-time processing and forming by laser, shortens the time (about 15-20 seconds) for processing a single expansion hole, and greatly improves the processing efficiency.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention and accompanying drawings are described in detail below.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is a cross-sectional view of the expansion hole size;

Fig. 2 is the structural representation of A-A;

Fig. 3a to Fig. 3f are the whole hole-making flowchart of millisecond long-pulse laser processing expansion hole;

Figure 4a is a schematic diagram of the expanded hole after the millisecond long pulse laser firstly processes the expanded hole and then sprays the thermal barrier coating;

Figure 4b is the actual picture of the expanded hole after the millisecond long pulse laser processing the expanded hole and then spraying the thermal barrier coating;

Figure 4c is an actual view of another perspective of the expanded hole after the millisecond long pulse laser processing the expanded hole and then spraying the thermal barrier coating;

Fig. 5 is a schematic diagram of the structure of millisecond long pulse laser processing the expansion hole with thermal barrier coating.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "horizontal", "inner", "outer" and so on is based on the orientation or positional relationship shown in the drawings, or is The usual orientation or positional relationship of the application product in use is only for the convenience of describing the application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as limiting the application. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not mean that the components are absolutely horizontal or vertical, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of this application, it should also be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, It can also be a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

Example

The processing method of the present invention is based on six-axis linkage CNC machine tool control, matched with millisecond long pulse laser, and realized in a three-dimensional space by precise cutting. During the entire expansion hole processing cycle, the laser beam is always parallel to the axis of the expansion hole.

As shown in Figure 1 and Figure 2, the expansion hole structure, from the inlet end to the outlet end, includes a circular and straight cut-off section 1, a diffuser section 3 and an expansion section 4, and the angle 6 between the hole and the wall surface is 20-30 degrees when formed. , after the airflow flows through the cooling hole, a layer of air film will be formed on the wall surface, which improves the cooling coverage and can effectively cool down the hot end parts of the combustion chamber, prolonging the life of the hot end parts; the circular straight cut-off section is a cylindrical through hole, Tangent to the smooth transition at the end of the diffusion section, the diffusion section is in the shape of a fan, and the two end faces 8 are semi-circular transitions; the expansion section is a bevel added to one side of the diffusion section, and the end edge 9 is a circular arc transition.

As shown in Figure 3a to Figure 3f, a millisecond long pulse laser processing method for expanding holes, the specific processing steps are:

Step 1, using the laser focal length adaptive function of the CNC machine tool, focus the laser on the center 5 of the hole to be processed on the surface, adjust the axis where the laser head is located to coincide with the axis 2 of the expanded hole to be processed, and realize positioning initialization;

Step 2, enable the plane rotation function of the CNC machine tool to rotate the processing plane to be perpendicular to the beam axis, move the laser focus to the center of the hole expansion section, and move the laser head alternately laterally along the centerline of the expansion section to both ends until the end of the diffusion section On the side, multiple single pulses are used to process the hole expansion section during the movement; the processing sequence is 10→11, and the expansion section is progressively carried out in layers, and the progressive range determines the size of the expansion angle 7 (set according to needs);

Step 4, focus the laser on the central processing area of the hole to be processed on the surface of the hole diffusion section, and multiple continuous pulses penetrate the base metal layer, and the rough-machined through-hole diameter is 2/3 of the diameter of the straight section of the hole, so that the subsequent scanning The metal oxide and metal splash produced by the type pass through the hole;

Step 5: Return the laser focus to the center 5 of the hole to be processed on the surface of the hole diffusion section. The laser head moves laterally along the centerline 2 of the diffusion section to both ends alternately. During the movement, multiple single pulses are used to process the hole diffusion section.

Step 6: Return the laser focus to the center of the hole to be processed on the surface of the diffusion section 5, and use the pulsed laser to rotate clockwise to cut the straight section of the cylindrical hole to the set size.

During the laser drilling process, the expansion section, the diffusion section and the circular straight cut-off section are sequentially processed in layers. The pulses emitted by each layer are symmetrical from the center of the hole pattern to the two ends of the divergence angle. The increase or decrease of energy determines the divergence angle of the diffusion section. .

Embodiment one

The method of millisecond long pulse laser drilling and then coating processing expansion hole:

The expansion hole is processed according to the steps in the embodiment, and the thermal barrier coating is prepared on the expansion hole at a certain angle (the angle set by those skilled in the art), as shown in Figure 4a. The expansion hole after spraying is as follows: Figure 4b and Figure 4c.

Embodiment two

Method of millisecond long pulse laser processing expanded hole with thermal barrier coating:

Firstly, process the thermal barrier coating on the target area on the side surface of the expansion hole coating, and the processing depth shall be based on just removing the coating to expose the metal substrate, as shown in Figure 5.

Other steps are the same as the steps in the embodiment, and will not be repeated.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can be made without departing from the technical principle of the present invention. and modifications, these improvements and modifications should also be considered as the protection scope of the present invention.

Claims (7)

1. A method of millisecond long pulse laser processing expansion hole, is characterized in that, comprises the following steps: Step 1: Positioning, use the adaptive laser focal length of the CNC machine tool to focus the laser on the center of the hole to be processed on the surface, adjust the axis where the laser head is located to coincide with the axis of the expansion hole to be processed, and realize positioning initialization; Step 2: Process the hole expansion section, enable the plane rotation of the CNC machine tool, rotate the processing plane to be perpendicular to the beam axis, move the laser focus to the center of the hole expansion section, and move the laser head alternately laterally along the centerline of the expansion section to both ends until On the end edge, the hole expansion section is processed with multiple single pulses during the movement; Step 3: Focus the laser on the center of the hole to be processed on the surface of the hole diffusion section, and multiple continuous pulses penetrate the base metal layer, so that the metal oxide and metal splash generated by the subsequent scanning pass through the hole; Step 4: Return the laser focus to the center of the hole to be processed on the surface of the hole diffusion section, and the laser head moves laterally along the centerline of the diffusion section to both ends alternately, and process the hole diffusion section with multiple single pulses during the movement; Step 5: Return the laser focus to the center of the hole to be processed on the surface of the diffusion section, and use the pulsed laser to rotate and cut the straight section of the cylindrical hole to the set size. 2. The method for machining expanded holes with a millisecond long pulse laser according to claim 1, characterized in that: based on the six-axis linkage CNC machine tool control, matching the millisecond long pulse laser, the laser beam is always in contact with the special-shaped hole during the entire processing cycle axis parallel. 3. A kind of millisecond long-pulse laser processing method for expanding holes according to claim 1, characterized in that: the laser hole-making process layers and sequentially processes the expansion section, the diffusion section and the circular straight cut-off section, and the pulse emitted by each layer It is carried out symmetrically from the center of the hole to the two ends of the divergence angle, and the increase or decrease of energy determines the divergence angle of the diffusion section. 4. A method for processing an expanding hole with a millisecond long pulse laser according to any one of claims 1 to 3, characterized in that there is no thermal barrier coating on the surface of the workpiece. 5 . The method for processing an expanding hole with a millisecond long pulse laser according to any one of claims 1 to 3 , characterized in that: the surface of the workpiece contains a thermal barrier coating. 6 . 6 . The method for machining expanded holes with millisecond long pulse laser according to claim 1 , characterized in that: the expanded hole structure is formed by millisecond long pulse laser processing. 7 . 7. A method for machining expansion holes with millisecond long pulse laser according to claim 6, characterized in that: the structure of the expansion hole structure from the inlet end to the outlet end includes a circular and straight cut-off section, a diffusion section and an expansion section, Among them, the circular straight cut-off section is a cylindrical through hole, which is tangent to the smooth transition at the end of the diffusion section. The edge is a circular arc transition structure.

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