A low-pressure laser welding method applied to a small-diameter closed weld of a microstructure

Abstract

The present application relates to a kind of low-pressure laser welding method applied to microstructure small diameter closed weld, comprising: fuel medium transmission part is assembled with oxidant medium transmission part, and laser welding dot positioning and fixed after;Laser probe is selected coordinate point along weld circumference, and weld path is fitted by interpolation calculation method, laser emitter is operated, so that laser point movement path coincides with weld, and working path is determined;Laser emitter rotates to starting point of arc with varying process parameters along the starting point of arc, and closed weld welding is completed, during weld welding process: based on the penetration of product, laser power and working distance are set, power P=300×Hd, starting point of arc working distance, i.e. H1 It is Δ0±0.2mm, and the working distance H2 of arc position is Δ0+5mm.The present application solves the problem that traditional laser welding cannot guarantee the penetration of microstructure small diameter closed weld and the smaller welding deformation amount.

Description

Technical Field

[0001] This invention relates to a low-pressure laser welding method for small-diameter closed welds in microstructures, belonging to the field of metal fusion welding technology. Background Technology

[0002] A certain type of dual-component low-thrust attitude control thrust chamber is powered by the impact, atomization, and reaction of two working media: an oxidizer and fuel. The impact angle and the atomization effect after impact are entirely determined by the structure of the core component, which is closely related to the welding method of this core component. The core component is composed of two micro-structured parts welded together. Both parts have multiple micro-pores. Controlling the deformation of the two parts during the welding process directly affects the impact angle and atomization effect of the two working media flowing out of the welded product. At the same time, the reliability of the weld structure ensures that the two working media do not come into premature contact inside the product, eliminating the risk of explosive combustion caused by violent reactions of the working media inside the product.

[0003] Traditional laser welding methods are only suitable for welding large-diameter products with high penetration depth. Welding deformation has almost no impact on large-sized products. However, for micro-structured small-diameter closed welds, traditional laser welding processes cannot simultaneously achieve both weld penetration depth and welding deformation. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a low-pressure laser welding method for small-diameter closed welds of microstructures, which solves the problem that traditional laser welding cannot guarantee the penetration depth and the amount of welding deformation of small-diameter closed welds of microstructures.

[0005] The solution of the present invention is:

[0006] A low-pressure laser welding method for small-diameter closed welds in microstructures is disclosed. The method involves welding a fuel medium transport component and an oxidant medium transport component to form a closed weld. This closed weld is an end-face weld located within an annular groove. Microholes with a diameter not exceeding 0.4 mm are provided on both the fuel medium transport component and the oxidant medium transport component.

[0007] include:

[0008] After assembling the fuel medium transmission component and the oxidant medium transmission component, laser welding is used to mark the positioning and fix them.

[0009] Based on the working coordinate system of the equipment, 8 to 16 coordinate points are selected along the circumference of the weld using a laser probe. The weld path is fitted by interpolation calculation method. The laser emitter is run so that the movement path of the laser point coincides with the weld to determine the working path.

[0010] The laser emitter rotates along the starting point of the arc termination segment to the arc initiation point with varying process parameters, completing the closed weld. During the weld welding process: the laser power and working distance are set based on the product's penetration depth. The power P = 300 × Hd, where P is the laser power and Hd is the product penetration depth. The arc initiation working distance, H1, is Δ0 ± 0.2 mm, and the arc termination working distance, H2, is Δ0 + 5 mm, where Δ0 represents the focusing state of the laser focus on the front surface of the product.

[0011] Furthermore, after assembling the fuel medium transmission component and the oxidant medium transmission component, 4 to 8 welding positioning points are evenly distributed along the circumference to fix the two components.

[0012] Furthermore, the weld path function expression is fitted using an interpolation calculation method: X 2 +Y 2 =R 2 X and Y are the coordinate values ​​of the working coordinate system, and R is the fitted weld radius.

[0013] Furthermore, the ambient pressure during the welding process is ≤10Pa.

[0014] Furthermore, during welding, the criterion is that no melting phenomenon occurs at the center of the small-diameter end face circular weld, and the angular velocity ω=V / R, where V is the linear velocity and R is the weld radius. When converted to linear velocity V, the linear velocity is not less than 20mm / s.

[0015] A low-pressure laser welding system for small-diameter closed welds in microstructures includes:

[0016] Laser emitter working path determination module:

[0017] After assembling the fuel medium transmission component and the oxidant medium transmission component, laser welding is used to mark the positioning and fix them.

[0018] Based on the working coordinate system of the equipment, 8 to 16 coordinate points are selected along the circumference of the weld using a laser probe. The weld path is fitted by interpolation calculation method. The laser emitter is run so that the movement path of the laser point coincides with the weld to determine the working path.

[0019] Closed weld welding module: The laser emitter rotates along the starting point of the arc termination segment to the arc initiation point with varying process parameters to complete the closed weld welding. During the weld welding process: the laser power and working distance are set based on the product's penetration depth. The power P = 300 × Hd, where P is the laser power and Hd is the product penetration depth. The arc initiation working distance, H1, is Δ0 ± 0.2 mm, and the arc termination working distance, H2, is Δ0 + 5 mm, where Δ0 represents the focusing state of the laser focus on the front surface of the product.

[0020] During welding, the standard is that the center of the small-diameter end face circular weld should not melt, and the angular velocity ω=V / R, where V is the linear velocity and R is the weld radius. When converted to linear velocity V, the linear velocity should not be less than 20mm / s.

[0021] The advantages of this invention compared to the prior art are:

[0022] (1) This invention provides an effective welding method for high-quality welding of fine structures with dense weld seams, especially for small-diameter end face weld seams with centrally distributed injection holes, which can eliminate the central melting phenomenon and ensure the laminar flow characteristics of liquid flow.

[0023] (2) By reducing the environmental pressure during laser welding, the present invention improves the aspect ratio to a limited extent, thereby reducing the heat input of the product and suppressing product deformation while meeting the drawing requirements.

[0024] (3) This invention is applicable to the welding of materials such as titanium alloys, stainless steel and aluminum alloys, and has universality. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the welded structure;

[0026] Figure 2 Welding path positioning diagram;

[0027] Figure 3 Schematic diagram of the welding process;

[0028] Figure 4 This is a welding process flowchart.

[0029] In the diagram: 1-Fuel medium transport component; 2-Oxidant medium transport component; 3-Closed weld; 4-Laser emitter; 5-Arc termination section;

[0030] The symbols in the diagram mean: A - the starting point of the arc; B - the starting point of the ending arc. Detailed Implementation

[0031] The present invention will be further described below with reference to the embodiments.

[0032] A low-pressure laser welding method for small-diameter closed welds in microstructures, such as... Figure 1-4 As shown, it is formed by welding fuel medium transmission parts and oxidant medium transmission parts to form a closed weld. The closed weld is an end face weld located in the annular groove. Micropores are provided on the fuel medium transmission parts and oxidant medium transmission parts. The diameter of the micropores is no greater than 0.4 mm, and the diameter of the small diameter of the microstructure is 3-6 mm.

[0033] include:

[0034] Determine the working path of the laser emitter:

[0035] After assembling the fuel medium transmission component and the oxidant medium transmission component, laser welding is used to mark the positioning points. Four to eight welding positioning points are evenly distributed along the circumference to fix the two types of components.

[0036] Based on the equipment's working coordinate system, 8–16 coordinate points are selected along the circumference of the weld using a laser probe. The weld path function expression is then fitted using interpolation calculations: X 2 +Y 2 =R 2 X and Y are the coordinate values ​​of the working coordinate system, and R is the fitted weld radius. Select the working mode without welding energy input to run the laser emitter, and observe the degree of overlap between the laser point movement path and the weld on the device display to determine the correctness of the working path.

[0037] Controlling environmental pressure during product welding process:

[0038] Before welding, reduce the ambient pressure and ensure that the ambient pressure during the welding process is ≤10Pa. For titanium alloys and aluminum alloys, the ambient pressure during the welding process needs to be ≤3Pa.

[0039] The laser emitter rotates along the starting point of the arc termination segment to the starting point with varying process parameters, completing the closed weld:

[0040] The laser power, working distance, and angular velocity are determined according to the product's penetration depth. The power generally follows the formula P = 300 × Hd, where P represents the laser power and Hd represents the product's penetration depth. The arc-starting working distance, H1, is preferably selected as Δ0 ± 0.2 mm, and the arc-ending working distance, H2, is preferably selected as Δ0 + 5 mm, where Δ0 represents the focusing state of the laser focus on the front surface of the product. During the test, the criterion is that no melting phenomenon occurs at the center of the small-diameter end face circular weld, and the angular velocity ω = V / R, which is converted to a linear velocity V, ensuring that the linear velocity is not less than 20 mm / s, where V is the linear velocity and R is the weld radius.

[0041] Example 1

[0042] See Figure 1 The present invention discloses a microstructure product with a small-diameter closed weld, which is formed by welding a fuel medium transport component 1 and an oxidant medium transport component 2. The closed weld 3 is an end face weld located in an annular groove.

[0043] Example 2

[0044] See Figure 2 In this embodiment, a point is taken every 60 degrees along the circumference of the weld, for a total of 6 points. Using the worktable as a coordinate system, the coordinates of the selected points are interpolated to obtain the working path equation. The working path is then run once in advance to confirm the correctness of the working path setting.

[0045] Example 3

[0046] See Figure 3 In this embodiment, under low pressure, the laser emitter rotates from the starting point of the arc segment along the working path to the starting point of the arc segment, maintaining constant power Q, working distance H1, and angular velocity ω. Subsequently, the laser emitter rotates from the starting point of the arc segment back to the starting point, maintaining constant power Q, adjusting the working distance, and changing the rotation from uniform speed to uniform deceleration. When the laser emitter reaches the starting point, the working distance increases from H1 to H2, and the angular velocity decreases from ω to 0.

[0047] This invention has three main aspects: First, by reducing the pressure environment during laser welding and minimizing the reflection of the laser by the welding plasma, the laser utilization rate is increased from 20% to over 50%, improving the depth-to-width ratio of the weld. Second, by employing a welding lens with long focusing capability, the diameter of the laser spot is reduced, minimizing the heat conduction from the circular weld face to the center and eliminating the central melting phenomenon. Third, by using a vertically stretched welding torch with a tapered arc section, the laser welding process is transformed from deep penetration welding to heat conduction welding, eliminating the problem of poor arc formation during low-vacuum welding.

[0048] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A low-pressure laser welding method for small-diameter closed welds in microstructures, characterized in that, It is formed by welding fuel medium transmission parts and oxidant medium transmission parts to form a closed weld. The closed weld is an end face weld located in the annular groove. Microholes are provided on the fuel medium transmission parts and oxidant medium transmission parts, and the diameter of the microholes is no greater than 0.4 mm. include: After assembling the fuel medium transmission component and the oxidant medium transmission component, laser welding is used to mark the positioning and fix them. Based on the working coordinate system of the equipment, several coordinate points are selected along the circumference of the weld using a laser probe. The weld path is fitted by interpolation calculation method. The laser emitter is run so that the movement path of the laser point coincides with the weld, and the working path is determined. The laser emitter rotates along the starting point of the arc termination segment to the starting point with varying process parameters, completing the closed weld. During the weld welding process: the laser power and working distance are set based on the product's penetration depth, with power P = 300 × Hd , where P is the laser power; Hd The arc initiation working distance, H1, is Δ0±0.2mm, and the arc termination working distance, H2, is Δ0+5mm, where Δ0 represents the focusing state of the laser focus on the front surface of the product. During welding, the ambient pressure is ≤10Pa. For titanium alloys and aluminum alloys, the ambient pressure is ≤3Pa. Based on the working coordinate system of the equipment, 8 to 16 coordinate points are selected along the circumference of the weld using a laser probe. In a low-pressure environment, the laser emitter rotates from the starting point of the arc along the working path to the starting point of the arc termination segment, keeping the power Q, working distance H1, and angular velocity ω constant during this process. Subsequently, the laser emitter rotates from the starting point of the arc termination segment along the working path to the starting point, keeping the power Q constant, adjusting the working distance, and changing the rotation process from uniform speed to uniform deceleration. When the laser emitter rotates to the starting point, the working distance increases from H1 to H2, and the angular velocity decreases from ω to 0.

2. The low-pressure laser welding method for small-diameter closed welds in microstructures according to claim 1, characterized in that, After assembling the fuel medium transmission component and the oxidant medium transmission component, 4 to 8 welding positioning points are evenly distributed along the circumference to fix the two components.

3. The low-pressure laser welding method for small-diameter closed welds in microstructures according to claim 1, characterized in that, The weld path function expression is fitted using interpolation calculation method: X 2 +Y 2 =R 2 X and Y are the coordinate values ​​of the working coordinate system, and R is the fitted weld radius.

4. The low-pressure laser welding method for small-diameter closed welds in microstructures according to claim 1, characterized in that, During welding, the standard is that the center of the small-diameter end face circular weld should not melt, and the angular velocity ω=V / R1, where V is the linear velocity and R1 is the weld radius. When converted to linear velocity V, the linear velocity should not be less than 20mm / s.

5. A low-pressure laser welding system for small-diameter closed welds in microstructures, used in the low-pressure laser welding method for small-diameter closed welds in microstructures as described in any one of claims 1 to 4, characterized in that, include: Laser emitter working path determination module: After assembling the fuel medium transmission component and the oxidant medium transmission component, laser welding is used to mark the positioning and fix them. Based on the working coordinate system of the equipment, several coordinate points are selected along the circumference of the weld using a laser probe. The weld path is fitted by interpolation calculation method. The laser emitter is run so that the movement path of the laser point coincides with the weld, and the working path is determined. Closed weld seam welding module: The laser emitter rotates along the starting point of the arc termination segment to the starting point with varying process parameters, completing the closed weld. During the weld welding process: the laser power and working distance are set based on the product's penetration depth, with power P = 300 × Hd , where P is the laser power; Hd The arc initiation working distance, H1, is Δ0±0.2mm, and the arc termination working distance, H2, is Δ0+5mm, where Δ0 represents the focusing state of the laser focus on the front surface of the product. During welding, the standard is that the center of the small-diameter end face circular weld should not melt, and the angular velocity ω=V / R1, where V is the linear velocity and R1 is the weld radius. When converted to linear velocity V, the linear velocity should not be less than 20mm / s. Micropores are provided on the fuel medium transmission parts and the oxidant medium transmission parts, and the diameter of the micropores is no greater than 0.4 mm; The ambient pressure during welding is ≤10Pa; for titanium alloys and aluminum alloys, the ambient pressure during welding is ≤3Pa; based on the working coordinate system of the equipment, 8 to 16 coordinate points are selected along the circumference of the weld using a laser probe. In a low-pressure environment, the laser emitter rotates from the starting point of the arc along the working path to the starting point of the arc termination segment, keeping the power Q, working distance H1, and angular velocity ω constant during this process. Subsequently, the laser emitter rotates from the starting point of the arc termination segment along the working path to the starting point, keeping the power Q constant, adjusting the working distance, and changing the rotation process from uniform speed to uniform deceleration. When the laser emitter rotates to the starting point, the working distance increases from H1 to H2, and the angular velocity decreases from ω to 0.

6. The low-pressure laser welding system for small-diameter closed welds in microstructures according to claim 5, characterized in that, It is formed by welding fuel medium transport parts and oxidant medium transport parts to form a closed weld, which is an end face weld located in the annular groove.

7. A low-pressure laser welding system for small-diameter closed welds in microstructures according to claim 5, characterized in that, After assembling the fuel medium transmission component and the oxidant medium transmission component, 4 to 8 welding positioning points are evenly distributed along the circumference to fix the two components.

8. A low-pressure laser welding system for small-diameter closed welds in microstructures according to claim 5, characterized in that, The weld path function expression is fitted using interpolation calculation method: X 2 +Y 2 =R 2 X and Y are the coordinate values ​​of the working coordinate system, and R is the fitted weld radius.

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