Cooling water channel welding machining method based on friction stir welding

Abstract

The invention provides a cooling water channel welding machining method based on friction stir welding, and belongs to the technical field of metal material welding. The cooling water channel welding machining method comprises the following steps that a stirring head is selected, and the length of a stirring needle is smaller than the thickness of a to-be-machined plate; a to-be-machined plate is fixed, a cooling water channel machining path of the to-be-machined plate is obtained, stirring head operation parameters are set, a stirring head is controlled to move along the cooling water channel machining path, and a hollow water channel corresponding to the cooling water channel machining path is formed in the to-be-machined plate through friction stir welding heat input. According to the cooling water channel welding machining method based on friction stir welding, the working procedures are simplified, the CNC preprocessing and cover plate assembling steps are omitted, the hollow water channel can be directly formed in the welding process, the efficiency is remarkably improved, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material welding, and more specifically, relates to a cooling water channel welding processing method based on stir friction welding. Background Art

[0002] A water-cooled plate is a device that achieves efficient heat dissipation through cooling water circulation and is widely used in electronic equipment, new energy vehicles, energy storage systems, etc. Its core principle is to use the flow of cooling water in a closed flow channel to quickly conduct the heat of the heat-generating components and dissipate it to the external environment, thereby ensuring stable operation of the equipment.

[0003] The manufacturing of traditional water cooling plates is generally carried out in the following steps: Figure 1 , first use CNC machining to machine the cooling water channel 300 on the base plate 100, then assemble the cover plate 200 and the base plate 100, and then use aluminum brazing or conventional friction stir welding process for welding and sealing. However, the above manufacturing method has some defects. First, the efficiency is low, because it takes a long time to pre-process the flow channel using CNC, and the cover plate needs to be assembled additionally; second, the cost is high, and multiple processes lead to increased processing time and material consumption; third, the strength is limited, the strength of the brazed joint is only 30%-50% of the parent material, and the sealing is easily affected by process fluctuations. In recent years, friction stir welding (FSW) has gradually been applied to water-cooled plate welding, but it still relies on pre-processed flow channels, and the efficiency and cost issues have not been solved. Therefore, there is an urgent need for a processing method that can directly form a sealing structure without pre-processing the flow channel. Summary of the invention

[0004] The object of the present invention is to provide a cooling water channel welding processing method based on stir friction welding, aiming to improve the processing efficiency of the cooling water channel on the water-cooling plate.

[0005] To achieve the above object, the technical solution adopted by the present invention is: to provide a cooling water channel welding processing method based on stir friction welding, comprising: S1: Select a stirring head, wherein the stirring head comprises a shaft shoulder and a stirring needle connected to the lower end surface of the shaft shoulder, and the length of the stirring needle is less than the thickness of the plate to be processed; S2: Clamp and fix the plate to be processed, and obtain a cooling water channel processing path of the plate to be processed; S3: Control the stirring head to move downward from the starting end of the cooling water channel processing path, so that the stirring needle penetrates into the plate to be processed, and when the shaft shoulder contacts the plate to be processed, stop the movement of the stirring head; S4: setting the operating parameters of the stirring head, the rotation speed is 700-1000 rpm, the welding speed is 200-700 mm / min, and the shoulder pressure is 0.1-0.3 mm; S5: Control the stirring head to move along the cooling water channel processing path, and form a hollow water channel corresponding to the cooling water channel processing path inside the plate to be processed through heat input of stir friction welding.

[0006] In a possible implementation, the stirring needle is a conical structure, the cone angle of the stirring needle is 20°-28°, and the surface of the stirring needle is provided with a spiral thread.

[0007] In a possible implementation, the length of the stirring needle is 2 / 3 of the thickness of the plate to be processed.

[0008] In a possible implementation, the ratio of the diameter of the shoulder to the diameter of the large end of the stirring needle is 2:1-3:1.

[0009] In one possible implementation, in step S5, the temperature of the working area of ​​the stirring head is monitored in real time, and the rotation speed and welding speed of the stirring head are dynamically adjusted according to the temperature of the working area, so that the heat input of the stir friction welding is controlled at 150-200 J / mm, and the fluctuation range of the temperature in the working area is controlled not to exceed ±10°C.

[0010] In a possible implementation, before step S3, the pre-processing area of ​​the plate to be processed is preheated at a temperature of 80°C-120°C.

[0011] In a possible implementation, the cooling water channel processing path is a multi-segment broken line or curve, and the stirring head reduces the welding speed to 200-300 mm / min at the corner of the cooling water channel processing path, and increases the rotation speed to 900-1000 rpm to ensure balanced heat input of stir friction welding.

[0012] In a possible implementation, the plate to be processed is a product made of aluminum alloy material.

[0013] In a possible implementation, the thickness of the plate to be processed is 3-12 mm.

[0014] In a possible implementation, the friction stir welding heat input is Q,

[0015] Among them, μ is the friction coefficient, N is the stirring head speed (r / min), F is the stirring head axial pressure (N), R is the shoulder radius (mm), and v is the welding speed (mm / min).

[0016] The beneficial effect of the cooling water channel welding processing method based on stir friction welding provided by the present invention is that: compared with the prior art, the cooling water channel welding processing method based on stir friction welding provided by the present invention simplifies the process, omits the CNC pre-processing and cover plate assembly steps, and can directly form a hollow water channel during the welding process, thereby significantly improving efficiency and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of a traditional water cooling plate; Figure 2 A flow chart of a cooling water channel welding processing method based on stir friction welding provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the front structural view of a stirring head provided in an embodiment of the present invention.

[0019] Description of reference numerals: 100, bottom plate; 200, cover plate; 300, cooling water channel; 1. Stirring head; 11. Shoulder; 12. Stirring needle. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] See also Figure 2 and Figure 3 Now, a cooling water channel welding method based on stir friction welding provided by the present invention is described. The cooling water channel welding method based on stir friction welding comprises the following steps: S1: Select a stirring head 1, wherein the stirring head 1 comprises a shaft shoulder 11 and a stirring needle 12 connected to the lower end surface of the shaft shoulder 11, and the length of the stirring needle 12 is less than the thickness of the plate to be processed; S2: Clamp and fix the plate to be processed, and obtain a cooling water channel processing path of the plate to be processed; S3: Control the stirring head 1 to move downward from the starting end of the cooling water channel processing path, so that the stirring needle 12 penetrates into the plate to be processed, and when the shaft shoulder 11 contacts the plate to be processed, stop the movement of the stirring head 1; S4: setting the operating parameters of the stirring head 1, the rotation speed is 700-1000 rpm, the welding speed is 200-700 mm / min, and the pressure of the shoulder 11 is 0.1-0.3 mm; S5: Control the stirring head 1 to move along the cooling water channel processing path, and form a hollow water channel corresponding to the cooling water channel processing path inside the plate to be processed through heat input of stir friction welding.

[0022] In the method of the present invention, the length of the stirring needle 12 is less than the thickness of the plate to be processed (rather than the traditional full-thickness penetration), and the plate to be processed is only partially penetrated during the stir friction welding process. An unplasticized area can be reserved at the bottom of the plate to be processed as the basis of the hollow waterway. During the operation, the rotating stirring needle 12 can push the material to flow to the periphery, so that the central area forms a cavity due to insufficient material filling. The shoulder 11 is pressed into the surface of the plate to be processed, and the surface material of the plate to be processed is plasticized and compacted by friction heat to ensure a smooth surface, while limiting the backflow of the material to the central area.

[0023] In the solution of the present invention, the above-mentioned friction stir welding heat input Q can be obtained by the following formula:

[0024] Where Q is the heat input (J / mm), μ is the friction coefficient, N is the stirring head speed (rpm), F is the axial pressure of the stirring head (N), R is the shoulder radius (mm), and v is the welding speed (mm / min).

[0025] In the present method, the high rotation speed (700-1000 rpm) of the stirring head 1 can generate sufficient friction heat to make the material reach a plastic state, and the medium welding speed (300-700 mm / min) of the stirring head 1 can control the heat input of the stir friction welding, avoid excessive melting or too fast cooling, ensure that the material flow is controllable, and form a low temperature-high temperature-low temperature thermal gradient in the operating center area of ​​the stirring head 1 through parameter combination, so as to promote the migration of the material from the center to the periphery and form a hollow cavity.

[0026] Overall, the dynamic process of machining cooling water channels by the method of the present invention can be divided into three stages.

[0027] Initial stage: The stirring needle 12 rotates and penetrates into the plate to be processed, so that the local material is plasticized and squeezed toward the periphery to form an initial cavity; Welding stage: the stirring head 1 moves along the cooling water channel processing path, and the stirring needle 12 continuously pushes the plasticized material to accumulate on both sides. The central area gradually expands into a continuous hollow water channel due to insufficient material replenishment; Cooling stage: The plasticized material solidifies under the pressure of the shoulder 11, forming a dense weld on the periphery, and the central cavity is retained as a sealed hollow water channel because it is not completely closed.

[0028] The present invention provides a cooling water channel welding processing method based on stir friction welding. Compared with the prior art, the process is simplified, CNC pre-processing and cover plate assembly steps are omitted, and a hollow water channel can be directly formed during the welding process, which significantly improves efficiency and reduces costs.

[0029] In practical applications, see Figure 2 The stirring needle 12 can be set to a conical structure, the cone angle a of the stirring needle 12 is 20°-28°, and a spiral thread is provided on the surface of the stirring needle 12, and the thread depth is set to 0.2-0.5 mm.

[0030] The tip of the conical stirring needle 12 is thinner, which can penetrate the material with lower resistance, reduce stress concentration in the initial stage, and reduce the risk of deformation of the plate to be processed. The conical structure gradually expands from the tip to the root, forming a gradient shear force, which pushes the plasticized material to flow evenly from the center to the periphery, reducing the risk of cavity collapse or uneven filling. In addition, compared with the cylindrical stirring needle 12, the conical structure has a more uniform stress distribution, avoiding the risk of fracture due to stress concentration at the root.

[0031] Setting the cone angle a of the stirring needle 12 to 20°-28° can reduce the wear of the stirring needle 12 while ensuring a sufficient material shear range to avoid local overheating caused by a too small angle (sharp) or an increase in material flow resistance caused by a too large angle (gentle).

[0032] By providing a spiral thread on the surface of the stirring needle 12, the stirring needle 12 can produce a "pumping effect", which pushes the plasticized material to migrate to both sides of the weld, reduces material accumulation in the central area, and promotes continuous forming of the hollow water channel.

[0033] In practical applications, the length of the stirring needle 12 is 2 / 3 of the thickness of the plate to be processed, and the ratio of the diameter of the shoulder 11 to the diameter of the large end of the stirring needle 12 is 2:1-3:1. Through the above settings, the stirring needle 12 only penetrates 2 / 3 of the thickness of the plate to be processed, and the unplasticized area at the bottom naturally forms a water channel foundation, avoiding the sealing risk caused by traditional full penetration. The diameter of the shoulder 11 is set to 2-3 times the diameter of the large end of the stirring needle 12, the significance of which is to expand the friction area of ​​the shoulder 11, ensure that the surface material is fully plasticized and compacted, prevent the cavity from being exposed, and reduce the width of the heat-affected zone.

[0034] In practical applications, when performing step S5, it is also necessary to monitor the temperature of the working area of ​​the stirring head 1 in real time, and dynamically adjust the rotation speed and welding speed of the stirring head 1 according to the temperature of the working area, so that the heat input of the friction stir welding is controlled at 150-200 J / mm, and the fluctuation range of the temperature of the working area is controlled not to exceed ±10°C. In application, when the heat input of the friction stir welding is too low (<150 J / mm), it will cause hole defects, resulting in discontinuity of the hollow water channel, forming breakpoints or local expansion. When the heat input of the friction stir welding is too high (>200 J / mm), it will cause the collapse of the hollow water channel. In this embodiment, the temperature of the working area of ​​the stirring head 1 is monitored in real time through a temperature detection device such as an infrared thermal imager, and the rotation speed and welding speed of the stirring head 1 are dynamically adjusted according to the temperature of the working area. The heat input of the friction stir welding can be controlled within an appropriate range, which can effectively eliminate holes and ensure that the water channel is continuous, sealed and high-strength.

[0035] In practical applications, before implementing step S3, the pre-processing area of ​​the plate to be processed needs to be preheated at a temperature of 80°C-120°C. Preheating can reduce the welding temperature difference, suppress residual stress, and prevent cold cracks. Preheating can also improve the initial plasticity of the material, making it easier for the stirring needle 12 to penetrate and reducing the sensitivity of process parameters.

[0036] In practical applications, the above-mentioned cooling water channel processing path is a multi-segment broken line or curve. The stirring head 1 reduces the welding speed to 200-300 mm / min at the corner of the cooling water channel processing path, and increases the rotation speed to 900-1000 rpm to ensure balanced heat input of the stir friction welding. By reducing the welding speed at the corner of the cooling water channel processing path, the heat action time can be extended, and by increasing the rotation speed, the heat loss can be compensated to prevent the hollow water channel from being interrupted.

[0037] In practical applications, the above-mentioned panels to be processed are aluminum alloy products, and the thickness of the panels to be processed is 3-12mm. In practical applications, the panels to be processed are 6061, 6063 or 7075 aluminum alloys. 6061 / 6063 aluminum alloys have good plasticity and are easy to form stable cavities; 7075 aluminum alloys are high-strength, and strength and formability can be taken into account through parameter optimization. The thickness of the panels to be processed is 3-12mm, covering the needs of electronic radiators (thin plates) to industrial cold plates (thick plates), and the process is highly universal.

[0038] The following are specific embodiments: Select 6061 aluminum alloy plate with a thickness of 6 mm; Select a stirring head with a stirring needle of 4 mm in length and 3 mm in diameter, with threads on the stirring needle and a cone angle of 24°; Set the stirring head operating parameters, speed 900 rpm, welding speed 500 mm / min, shoulder pressure 0.2 mm; Control the stirring head to process along the preset cooling water channel processing path to form a hollow water channel with a cross-sectional width of 2.5 mm and a height of 1.5 mm; After testing, the strength of the processed area of ​​the aluminum alloy plate is 85% of the parent material, and the water channel sealing has passed the 2MPa hydraulic test.

[0039] The core principle of the method of the present invention to form a hollow water channel by friction stir welding is "control instead of milling". Through specially designed stirring heads and process parameters, the traditional water channel structure that requires mechanical processing is transformed into a cavity formed dynamically during the welding process. The method of the present invention breaks through the limitation of traditional FSW that is only used for connection, realizes structure-function integrated manufacturing, significantly improves efficiency and reduces costs.

[0040] The above-mentioned "control instead of milling" means that by precisely controlling the welding process parameters and the design of the stirring head, the internal structure (such as cooling water channels) is directly formed during the friction stir welding (FSW) process, thereby replacing the pre-processing steps of traditional mechanical milling (CNC machining). Its essence is to integrate structural processing and welding into one step to achieve "manufacturing is forming".

[0041] In the method of the present invention, the specific implementation of "control" includes the following three aspects: (1) Process parameter control Stirring head heat input adjustment: High speed (700-1000 rpm): increases friction heat to fully plasticize the material; Medium welding speed (300-700 mm / min): Balance heat accumulation with material flow rate to avoid overheating or cooling too quickly.

[0042] Downward pressure control (0.1-0.3mm): The shoulder compacts the surface material to prevent the cavity from being exposed and limit the material from flowing back to the center.

[0043] (2) Mixing head design control Shorten the stirring needle (2 / 3 of the plate thickness): only penetrate part of the plate, and the unplasticized area at the bottom is reserved as a water channel space; Thread structure: Enhances the "pumping effect" of the material, pushing the plasticized metal to accumulate on both sides, and the central area forms a cavity due to insufficient filling; Optimized shoulder size (diameter to stirring needle ratio 2:1-3:1): expand the heat affected zone and improve surface sealing.

[0044] (3) Material flow control Dynamic plasticization: When the stirring head moves, the threaded stirring needle continuously squeezes the material from the center to the periphery to form a continuous cavity; Gradient thermal field: The temperature at the center of the weld is high and the temperature at the periphery is low, which promotes the migration of materials from the inside to the outside and further stabilizes the waterway structure.

[0045] The application significance of the method of the present invention is: 1. Simplified process: eliminating CNC processing, cover assembly, secondary welding and other steps; 2. Cost reduction: reduce equipment investment (such as milling machines) and material waste (no chips generated); 3. Performance improvement: The weld and water channel are integrated to avoid the risk of leakage caused by assembly gaps; the strength of the welding area is close to that of the parent material, and the sealing meets high-pressure working conditions (1.5-2 MPa); 4. Environmental protection: no cutting fluid pollution, energy consumption is only 60%-70% of traditional process.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cooling water channel welding processing method based on stir friction welding, characterized in that: The following steps are involved: S1: Select a stirring head, wherein the stirring head comprises a shaft shoulder and a stirring needle connected to the lower end surface of the shaft shoulder, and the length of the stirring needle is less than the thickness of the plate to be processed; S2: Clamp and fix the plate to be processed, and obtain a cooling water channel processing path of the plate to be processed; S3: Control the stirring head to move downward from the starting end of the cooling water channel processing path, so that the stirring needle penetrates into the plate to be processed, and when the shaft shoulder contacts the plate to be processed, stop the movement of the stirring head; S4: setting the operating parameters of the stirring head, the rotation speed is 700-1000 rpm, the welding speed is 200-700 mm / min, and the shoulder pressure is 0.1-0.3 mm; S5: Control the stirring head to move along the cooling water channel processing path, and form a hollow water channel corresponding to the cooling water channel processing path inside the plate to be processed through heat input of stir friction welding.

2. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: The stirring needle is of a conical structure, the cone angle of the stirring needle is 20°-28°, and the surface of the stirring needle is provided with a spiral thread.

3. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: The length of the stirring needle is 2 / 3 of the thickness of the plate to be processed.

4. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: The ratio of the diameter of the shaft shoulder to the diameter of the large end of the stirring needle is 2:1-3:

1.

5. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: In step S5, the temperature of the working area of ​​the stirring head is monitored in real time, and the rotation speed and welding speed of the stirring head are dynamically adjusted according to the temperature of the working area, so that the heat input of the stir friction welding is controlled at 150-200 J / mm, and the fluctuation range of the temperature in the working area is controlled not to exceed ±10°C.

6. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: Before step S3, the pre-processing area of ​​the plate to be processed is preheated at a temperature of 80°C-120°C.

7. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: The cooling water channel processing path is a multi-segment broken line or curve. The stirring head reduces the welding speed to 200-300 mm / min at the corner of the cooling water channel processing path, and increases the rotation speed to 900-1000 rpm to ensure balanced heat input of stir friction welding.

8. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: The plate to be processed is an aluminum alloy product.

9. A method for processing cooling water channel welding based on friction stir welding as claimed in claim 8, characterized in that: The thickness of the plate to be processed is 3-12 mm.

10. A method for processing cooling water channel welding based on stir friction welding as claimed in claim 1, characterized in that: The friction stir welding heat input is Q, Among them, μ is the friction coefficient, N is the stirring head speed (r / min), F is the stirring head axial pressure (N), R is the shoulder radius (mm), and v is the welding speed (mm / min).

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