High-energy beam welding method for thin-wall complex flow channel liquid cooling structure

Abstract

The invention relates to a thin-wall complex flow channel liquid cooling structure high-energy beam welding method, and belongs to the field of metal materials and processes. Manufacturing an assembling and shape correcting clamp; the fixed base is horizontally placed, and the thin-wall complex flow channel liquid cooling structure is horizontally placed on the upper surface of the fixed base; horizontally placing a cover plate on the upper surface of the thin-wall complex flow channel liquid cooling structure; a pressing plate is horizontally placed on the upper surface of the cover plate; the pressing plate is fixedly connected with the fixed base through a tensioning screw; spot welding is conducted on the cover plate, and after spot welding is completed, the pressing plate is dismantled; formally welding the cover plate; after welding is completed, stress relief annealing treatment is conducted at high pressure and high temperature, and forming is conducted; according to the method, the welding seam is smooth and good in forming after welding, the internal quality meets the QJ20645-2016 requirement, the pressure of the laser welding seam is maintained for 60 min under 0.8 MPa, the laser welding seam is fatigued for 1000 weeks under 0.8 MPa, the leak rate is smaller than or equal to 1.0 * 10 <-10 > Pa.m < 3 > / s, the strength coefficient of a laser welding joint is larger than or equal to 0.9, and the flatness is smaller than or equal to 0.2 mm.

Description

Technical Field

[0001] The invention belongs to the field of metal materials and processes, and relates to a high-energy beam welding method for a thin-walled complex flow channel liquid cooling structure. Background Art

[0002] Active cooling structures such as flow channels and cavities have a large number of applications in the field of industrial electronic equipment, such as waveguides, antennas, liquid cooling plates, etc. Active cooling is suitable for situations where the structure is subjected to long-term, higher heat flux density pneumatic heating. The active cooling structure generally adopts a double-layer jacket thin-walled structure, one layer is a substrate, on which rectangular cross-section cooling channels are arranged in parallel, and the other layer is a cover plate. The two layers of thin plates are connected by welding to form a closed convex and concave cavity. The coolant continues to flow in the continuous channel, and through convection heat transfer and radiation heat transfer, the wall temperature is reduced, so that the temperature of the structure itself is kept in a low range. The active cooling structure has the characteristics of small channel cross-sectional size, dense, and complex structure. The structure requires high welding quality, high channel cavity size accuracy after welding, and high welding success rate, which makes welding extremely difficult. At present, the commonly used welding methods include TIG welding, vacuum brazing, high-energy beam welding, etc. TIG welding has a large heat input, large welding deformation, and serious joint softening phenomenon, and the welding quality cannot be guaranteed. Conventional vacuum brazing is limited by factors such as assembly quality, large-area diffusion, solder spreading and inability to repair welding and cannot meet welding requirements. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a high-energy beam welding method for thin-walled complex flow channel liquid cooling structure, so that the weld is smooth and well-formed after welding, and the internal quality meets the requirements of QJ20645-2016. The laser weld is maintained at 0.8MPa for 60min, fatigued for 1000 cycles at 0.8MPa, and the leakage rate is ≤1.0×10 -10 Pa·m 3 / s, laser welding joint strength coefficient ≥ 0.9, flatness ≤ 0.2mm.

[0004] The solution of the present invention is:

[0005] A high-energy beam welding method for a thin-walled complex flow channel liquid cooling structure, comprising:

[0006] Make assembly and alignment fixtures, including pressure plates and fixed bases;

[0007] The fixed base is placed horizontally, and the thin-walled complex flow channel liquid cooling structure is placed horizontally on the upper surface of the fixed base;

[0008] The cover plate is placed in a thin-walled complex flow channel liquid cooling structure;

[0009] The pressing plate is horizontally placed on the upper surface of the cover plate and the thin-walled complex flow channel liquid cooling structure; and the pressing plate is fixedly connected to the fixed base by tightening screws to achieve the compression of the thin-walled complex flow channel liquid cooling structure and the cover plate;

[0010] Spot weld the cover plate, and after spot welding is completed, remove the pressure plate;

[0011] Carry out formal welding on the cover plate;

[0012] After welding is completed, stress relief annealing is carried out under high pressure and high temperature to form the part.

[0013] In the above-mentioned high-energy beam welding method for a thin-walled complex flow channel liquid-cooled structure, the pressing plate and the fixed base are both square plate structures; the upper surface of the pressing plate is provided with square through holes; the square through holes are the subsequent spot welding positions.

[0014] In the above-mentioned high-energy beam welding method for a thin-walled complex flow channel liquid-cooled structure, the pressing plate and the fixed base are both made of copper; and the cover plate is made of titanium alloy.

[0015] In the above-mentioned high-energy beam welding method for a thin-walled complex flow channel liquid-cooling structure, the thin-walled complex flow channel liquid-cooling structure is a square plate structure; the upper surface of the thin-walled complex flow channel liquid-cooling structure is provided with a flow channel-shaped groove; the flow channel-shaped groove is a step groove structure.

[0016] In the above-mentioned high-energy beam welding method for a thin-walled complex flow channel liquid-cooling structure, the cover plate is a flow channel plate-shaped structure; the shape of the cover plate corresponds to the shape of the flow channel-shaped groove; the cover plate is covered in the flow channel-shaped groove to achieve the upper surface of the cover plate being coplanar with the upper surface of the thin-walled complex flow channel liquid-cooling structure; the lower surface of the cover plate and the remaining space of the flow channel-shaped groove form a flow channel.

[0017] In the above-mentioned high-energy beam welding method for a thin-walled complex flow channel liquid-cooling structure, after pressing, the fitting clearance between the upper surface of the fixed base and the lower plane of the thin-walled complex flow channel liquid-cooling structure is not greater than 0.1mm; the fitting clearance between the lower surface of the cover plate and the upper plane of the thin-walled complex flow channel liquid-cooling structure is not greater than 0.1mm; the offset clearance between the cover plate and the thin-walled complex flow channel liquid-cooling structure is not greater than 0.1mm; the spot welding position vacant in the square through hole of the pressure plate is 2-4mm away from the weld.

[0018] In the above-mentioned thin-walled complex flow channel liquid-cooled structure high-energy beam welding method, the spot welding power is 400-800W, the welding speed is 20-80mm / s, the defocus amount is -5~+5mm, the front shielding gas flow rate is 30-40L / min; the back shielding gas flow rate is 5-10L / min.

[0019] In the above-mentioned high-energy beam welding method for thin-walled complex flow channel liquid-cooled structure, the formal welding is divided into two stages, and the welding directions are opposite.

[0020] In the above-mentioned high-energy beam welding method for thin-walled complex flow channel liquid-cooled structure, the peak welding power of formal welding is 800W~1000W; the welding power valley is 100W-200W; the frequency is 25-50Hz; the welding speed is 20-80mm / s; the defocus amount is -5~+5mm; the front shielding gas flow rate is 30-40L / min; and the back shielding gas flow rate is 5-10L / min.

[0021] In the above-mentioned high-energy beam welding method for thin-walled complex flow channel liquid cooling structure, the parameters of the stress annealing treatment are:

[0022] The pressure value is 0.5-5MPa, the temperature is 600-700℃, and the insulation time is 2-5h.

[0023] The beneficial effects of the present invention compared with the prior art are:

[0024] (1) The present invention adopts laser welding for the first time for thin-walled complex flow channel liquid cooling structure. Through welding process research, the problems of high porosity sensitivity, easy collapse, poor sealing, etc. in thin-walled complex flow channel welding are solved;

[0025] (2) The weld appearance quality of the weld after welding is good, without defects such as undercut and inclusions, and the internal quality meets the requirements of QJ20645-2016. The joint strength coefficient is ≥0.9. The laser weld is maintained at 0.8 MPa for 60 minutes and fatigued at 0.8 MPa for 1000 cycles. The helium mass spectrometer leak rate is ≤1.0×10 -10 Pa·m 3 / s;

[0026] (3) The thickness of the body structure of the present invention is only 3mm, the thickness of the cover plate is only 1mm, the laser weld exceeds 2800mm, and it is single-sided welding, so the welding deformation is relatively large. The present invention designs a specific welding tool and a correction tool to achieve high-precision assembly of the structure, ensure the assembly gap and misalignment, and combine with high-temperature pressurized annealing heat treatment to eliminate welding stress and reduce welding deformation. After welding, the flatness of the thin-walled complex flow channel liquid cooling structure is ≤0.2mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the assembly of the thin-wall complex flow channel liquid cooling structure of the present invention;

[0028] Figure 2 It is a schematic diagram of the structure of the pressing plate of the present invention;

[0029] Figure 3 This is a schematic diagram of the fixed base structure of the present invention;

[0030] Figure 4This is a schematic diagram of the thin-walled complex flow channel liquid cooling structure of the present invention;

[0031] Figure 5 Schematic diagram of the cover plate of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the embodiments.

[0033] The present invention provides a high-energy beam welding method for a thin-walled complex flow channel liquid-cooled structure. Laser welding is used for the first time. Through welding process research, the problems of high porosity sensitivity, easy collapse, poor sealing, etc. in the welding of thin-walled complex flow channels are solved. After welding, the weld appearance quality is well formed without defects such as undercut and inclusions.

[0034] The high-energy beam welding method for thin-walled complex flow channel liquid cooling structure specifically includes the following steps:

[0035] Make an assembly and alignment fixture, including a pressing plate 1 and a fixed base 2. Figure 2 , 3 As shown, the pressing plate 1 and the fixed base 2 are both square plate structures; the upper surface of the pressing plate 1 is provided with a square through hole; the square through hole is the subsequent spot welding position. The pressing plate 1 and the fixed base 2 are both made of copper.

[0036] The fixed base 2 is placed horizontally, and the thin-walled complex flow channel liquid cooling structure is placed horizontally on the upper surface of the fixed base 2. In the present invention, the thin-walled complex flow channel liquid cooling structure is a square plate structure; the upper surface of the thin-walled complex flow channel liquid cooling structure is provided with a flow channel-shaped groove; the flow channel-shaped groove is a step groove structure, such as Figure 4 shown.

[0037] The cover plate is placed in the thin-walled complex flow channel liquid cooling structure; the cover plate is made of titanium alloy. The cover plate is a flow channel plate structure; the shape of the cover plate corresponds to the shape of the flow channel groove; the cover plate is covered in the flow channel groove to achieve the upper surface of the cover plate and the upper surface of the thin-walled complex flow channel liquid cooling structure to be coplanar; the lower surface of the cover plate and the remaining space of the flow channel groove form a flow channel, such as Figure 5 shown.

[0038] The pressing plate 1 is horizontally placed on the upper surface of the cover plate and the thin-walled complex flow channel liquid cooling structure; and the pressing plate 1 is fixedly connected to the fixed base 2 by tightening screws to achieve the compression of the thin-walled complex flow channel liquid cooling structure and the cover plate, such as Figure 1 shown.

[0039] After tightening, the fitting clearance between the upper surface of the fixed base 2 and the lower plane of the thin-walled complex flow channel liquid cooling structure is not greater than 0.1mm; the fitting clearance between the lower surface of the cover plate and the upper plane of the thin-walled complex flow channel liquid cooling structure is not greater than 0.1mm; the offset clearance between the cover plate and the thin-walled complex flow channel liquid cooling structure is not greater than 0.1mm; the spot welding position vacant in the square through hole of the pressure plate 1 is 2-4mm away from the weld.

[0040] Spot weld the cover plate, and after the spot welding is completed, remove the pressure plate 1. The spot welding power is 400-800W, the welding speed is 20-80mm / s, the defocusing amount is -5~+5mm, the front shielding gas flow rate is 30-40L / min; the back shielding gas flow rate is 5-10L / min.

[0041] The cover plate is formally welded. The formal welding is divided into two sections, and the welding directions are opposite. The peak power of the formal welding is 800W~1000W; the valley power is 100W-200W; the frequency is 25-50Hz; the welding speed is 20-80mm / s; the defocus is -5~+5mm; the front shielding gas flow is 30-40L / min; the back shielding gas flow is 5-10L / min.

[0042] After welding is completed, stress relief annealing is carried out under high pressure and high temperature to form the part.

[0043] The parameters of stress annealing treatment are:

[0044] The pressure value is 0.5-5MPa, the temperature is 600-700℃, and the insulation time is 2-5h.

[0045] Example

[0046] The invention is suitable for high-energy beam welding of a high-strength aluminum-lithium alloy thin-wall rib structure.

[0047] The specific steps of welding are:

[0048] Step 1: Design an assembly fixture and shape correction fixture that can be used for the above-mentioned structural welding. It consists of a copper pressure plate and a copper fixed base, which can realize compact assembly and shape correction, and leaves a vacant laser spot welding position;

[0049] Step 2: Use the copper pressure plate to fix the thin-walled complex flow channel liquid cooling structure and the cover plate on the copper fixed base through the tightening screws on the chassis. The profile is required to fit well, the clearance between the fixed base and the bottom plane = 0.1mm, the clearance between the cover plate and the thin-walled rib structure = 0.1mm, the offset clearance = 0.1mm, and the spot welding position of the pressure plate is 3mm away from the weld;

[0050] Step 3: Pickle the cover plate and thin-walled rib structure to ensure that there is no stain on the surface. Clean the surface of the part to be welded with anhydrous ethanol, and then dry it naturally or with a hair dryer.

[0051] Step 4: Turn on the argon gas for front and back gas protection, the front protection gas flow rate is 32L / min, and the back protection gas flow rate is 5L / min;

[0052] Step 5: Spot weld the cover plate first, the spot welding position is at the fixture hole position, the spot welding power is 600W, the welding speed is 40mm / s, and the defocus amount is 0mm;

[0053] Step 6: After spot welding, remove the spot welding fixture pressure plate, and then formally weld the ring cover. The formal welding is divided into two sections, the welding directions are opposite, the welding power peak is 950W, the welding power valley is 200W, the frequency is 30Hz, the welding speed is 30mm / s, the defocus amount is 0mm, the front shielding gas flow rate is 33L / min, and the back shielding gas flow rate is 6L / min;

[0054] Step 7: After laser welding is completed, the thin-walled complex flow channel liquid cooling structure is assembled on the correction tooling, and stress relief annealing treatment is carried out using high pressure and high temperature. The pressure value is 1MPa, the temperature is 650℃, and the insulation time is 3h.

[0055] After welding, the weld appearance was visually inspected. The weld appearance quality was good, without undercuts, inclusions and other defects. The internal quality was inspected by X-ray inspection, which met the requirements of QJ20645-2016. The tensile strength of the fusion weld joint was measured to be 1080MPa, and the joint strength coefficient was ≥0.9. The flatness of the bottom plate after welding was measured to be 0.2mm. The laser weld had no leakage after maintaining pressure at 0.8MPa for 60min and no leakage after fatigue for 1000 cycles at 0.8MPa. The leakage rate of helium mass spectrometry was 7.7×10 -11 Pa·m 3 / s.

[0056] The present invention adopts laser welding for the first time for thin-walled complex flow channel liquid cooling structure. Through welding process research, the problems of high porosity sensitivity, easy collapse, poor sealing, etc. in thin-walled complex flow channel welding are solved. The appearance quality of the weld after welding is good, without defects such as undercut and inclusion, and the internal quality meets the requirements of QJ20645-2016. The joint strength coefficient is ≥0.9, the laser weld is maintained at 0.8MPa for 60min, fatigued for 1000 cycles at 0.8MPa, and the helium mass spectrometer leak rate is ≤1.0×10 -10 Pa·m 3 / s;

[0057] The thickness of the body structure of the present invention is only 3mm, the thickness of the cover plate is only 1mm, the laser weld exceeds 2800mm, and it is single-sided welding, so the welding deformation is large. The present invention designs a specific welding tool and a correction tool to achieve high-precision assembly of the structure, ensure the assembly gap and misalignment, and combine high-temperature pressurized annealing heat treatment to eliminate welding stress and reduce welding deformation. After welding, the flatness of the thin-walled complex flow channel liquid cooling structure is ≤0.2mm.

[0058] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-energy beam welding method for thin-walled complex flow channel liquid cooling structure, characterized in that: include: Making an assembly and correction fixture, including a pressing plate (1) and a fixing base (2); The fixed base (2) is placed horizontally, and the thin-walled complex flow channel liquid cooling structure is placed horizontally on the upper surface of the fixed base (2); The cover plate is placed in a thin-walled complex flow channel liquid cooling structure; The pressing plate (1) is horizontally placed on the upper surface of the cover plate and the thin-walled complex flow channel liquid cooling structure; and the pressing plate (1) is fixedly connected to the fixed base (2) by tightening screws to achieve the pressing of the thin-walled complex flow channel liquid cooling structure and the cover plate; Spot welding is performed on the cover plate, and after the spot welding is completed, the pressure plate (1) is removed; Carry out formal welding on the cover plate; After welding is completed, stress relief annealing is carried out under high pressure and high temperature to form the part.

2. A thin-walled complex flow channel liquid cooling structure high energy beam welding method according to claim 1, characterized in that: The pressing plate (1) and the fixed base (2) are both square plate-shaped structures; the upper surface of the pressing plate (1) is provided with a square through hole; the square through hole is a subsequent spot welding position.

3. A thin-walled complex flow channel liquid cooling structure high energy beam welding method according to claim 1, characterized in that: The pressing plate (1) and the fixed base (2) are both made of copper material; the cover plate is made of titanium alloy material.

4. A thin-walled complex flow channel liquid cooling structure high energy beam welding method according to claim 1, characterized in that: The thin-walled complex flow channel liquid cooling structure is a square plate-shaped structure; the upper surface of the thin-walled complex flow channel liquid cooling structure is provided with a flow channel-shaped groove; the flow channel-shaped groove is a step groove structure.

5. A thin-walled complex flow channel liquid cooling structure high energy beam welding method according to claim 4, characterized in that: The cover plate is a flow channel plate-like structure; the shape of the cover plate corresponds to the shape of the flow channel-like groove; the cover plate is covered in the flow channel-like groove, so that the upper surface of the cover plate is coplanar with the upper surface of the thin-walled complex flow channel liquid cooling structure; the lower surface of the cover plate and the remaining space of the flow channel-like groove form a flow channel.

6. The high-energy beam welding method for thin-walled complex flow channel liquid cooling structure according to claim 2, characterized in that: After pressing, the matching clearance between the upper surface of the fixed base (2) and the lower plane of the thin-walled complex flow channel liquid cooling structure is not greater than 0.1mm; the matching clearance between the lower surface of the cover plate and the upper plane of the thin-walled complex flow channel liquid cooling structure is not greater than 0.1mm; the offset clearance between the cover plate and the thin-walled complex flow channel liquid cooling structure is not greater than 0.1mm; the spot welding position left by the square through hole of the pressing plate (1) is 2-4mm away from the weld.

7. A thin-walled complex flow channel liquid cooling structure high energy beam welding method according to claim 6, characterized in that: The spot welding power is 400-800W, the welding speed is 20-80mm / s, the defocus is -5~+5mm, the front shielding gas flow is 30-40L / min; the back shielding gas flow is 5-10L / min.

8. The high-energy beam welding method for thin-walled complex flow channel liquid cooling structure according to claim 1, characterized in that: The formal welding is divided into two sections, and the welding directions are opposite.

9. A high-energy beam welding method for thin-walled complex flow channel liquid cooling structure according to claim 8, characterized in that: The peak welding power of formal welding is 800W~1000W; the valley welding power is 100W-200W; the frequency is 25-50Hz; the welding speed is 20-80mm / s; the defocus is -5~+5mm; the front shielding gas flow is 30-40L / min; and the back shielding gas flow is 5-10L / min.

10. The high-energy beam welding method for thin-walled complex flow channel liquid cooling structure according to claim 1, characterized in that: The parameters of the stress annealing treatment are: The pressure value is 0.5-5MPa, the temperature is 600-700℃, and the insulation time is 2-5h.

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