A clamping correction method for a vacuum diffusion bonding microchannel cold plate

Abstract

The present invention relates to a clamping correction method for a vacuum diffusion bonding microchannel cold plate, belonging to the technical field of numerical control machining. It includes: before welding, machining multiple groups of measurement holes in the allowance removal area of the workpiece to be welded. Each group of holes includes a through hole and a flat-bottomed hole with the bottom surface flush with the bottom surface of the flow channel. After welding, collect the depth data of each group of holes and take the average value; use the least squares method to perform plane fitting on this value, and then obtain the neutral layer plane of the flow channel after welding; calculate the translation distance and two deflection angles between the normal vector of the neutral layer and the horizontal plane, and use this translation distance and angle as the part machining clamping correction value; when performing machining clamping, clamp and correct the vacuum diffusion bonding microchannel cold plate through this correction value, so as to machine a high-precision vacuum diffusion bonding microchannel cold plate.

Description

Technical Field

[0001] The present invention belongs to the technical field of numerical control machining. Background Art

[0002] In recent years, with the development of the electronic industry, the integration degree of active phased array radars has become higher and higher, and the heat flux density in the system has also become larger and larger. The heat generation of some chips has exceeded 100 W / cm2. If such high heat cannot be dissipated in time and effectively, it will seriously affect the working performance of the radar system. Due to the limitations of the equipment size and working conditions, ordinary forced air cooling and liquid cooling heat dissipation technologies cannot meet the heat dissipation requirements of future T / R components.

[0003] The emergence of microchannel cold plates provides a new method to solve this problem. It has the advantages of compact structure, high heat transfer efficiency, light weight, safe and reliable operation, etc., and is especially suitable for systems such as active phased array radars that have special requirements for the size and weight of heat exchange equipment. The difficulty of microchannel cold plates lies in the manufacturing process method. It is very important to adopt a welding process for the welding and forming of the cold plate cover plate and the bottom plate. In previous literature, vacuum aluminum brazing or gas shielded aluminum brazing was mostly used, but this process is prone to block the flow channels of microchannel cold plates, and the yield rate is relatively low. Diffusion welding belongs to solid-phase welding, which fundamentally solves the problem of blockage and can form a large-area welded joint. It is the trend of microchannel cold plate welding. The design concept of lightweight and high-efficiency heat dissipation occupies an important position in radar design, which requires the wall thickness of the cold plate flow channels to be relatively thin. During the processing of such diffusion-welded cold plates, the part deformation caused by welding is plastic deformation, resulting in a non-linear relationship between the flow channel compression amount and the entire part thickness compression amount. At present, non-destructive testing technologies cannot efficiently and accurately measure the flow channel depth and the position of the welding surface. If the position of the welding surface or the center layer of the flow channel cannot be accurately found and properly clamped and corrected, it is easy to cause uneven wall thickness on both sides of the flow channel or overcut on one side during processing, resulting in a bulging phenomenon on the overcut side of the cold plate during use. Summary of the Invention

[0004] In order to overcome the phenomenon of uneven wall thickness on both sides of the cold plate flow channel caused by welding plastic deformation, the present invention proposes a method for clamping and correcting a vacuum diffusion-welded microchannel cold plate.

[0005] The technical solution for realizing the present invention is as follows:

[0006] Before welding, multiple groups of measurement holes are machined in the remaining material removal area of the workpiece to be welded. The measurement holes are distributed according to the structural characteristics of the welded part. Each group of measurement holes includes a through hole and a flat-bottomed hole with the bottom surface flush with the bottom surface of the flow channel. After welding, the depth data of each group of measurement holes are collected; then, the average value of the depth values of each group of measurement holes collected is taken, and the least squares method is used to perform plane fitting on the average value. The obtained plane is the approximate neutral layer of the flow channel after vacuum diffusion welding, and the translation distance and two deflection angles between the neutral layer of the flow channel and the horizontal plane are calculated; finally, during machining clamping, the vacuum diffusion welding microchannel cold plate is clamped and corrected through this correction value, so as to machine a high-precision vacuum diffusion welding microchannel cold plate.

[0007] Through the present invention, the post-welding clamping of the vacuum diffusion welding cold plate can be efficiently and accurately corrected, avoiding inaccurate machining references caused by welding plastic deformation, over-cutting on one side of the flow channel, and bulging of the cold plate during use. Brief Description of the Drawings

[0008] Figure 1 Cross-sectional view of a group of measurement holes.

[0009] Figure 2 Map of measurement hole collection points on the vacuum diffusion welding microchannel cold plate after welding.

[0010] In the figure: 1. Flow channel, 2. Upper plate, 3. Measurement hole a, 4. Measurement hole b, 5. Remaining material removal area after welding, 6. Remaining area after welding, 7. Lower plate, 8. Welding surface, 9. Neutral layer surface of the flow channel, 10. Measurement hole, 11. Vacuum diffusion welding microchannel cold plate, 12. Cold plate welding blank. Detailed Embodiments

[0011] The present invention will be further explained and illustrated below in conjunction with the drawings and embodiments.

[0012] Before welding, the present invention first processes multiple groups of measurement holes in advance in the margin removal area. The number and distribution of the measurement holes satisfy the general statistical method. Each group of measurement holes consists of two holes, namely a through hole and a flat-bottom hole with the bottom surface flush with the bottom surface of the flow channel. After welding, the difference in the depth of each group of holes can reflect the flow channel compression amount and the welding plane position in this area. After welding, collect the depth data of each group of measurement holes; the depth data can be collected by using a depth gauge or the tool setting method of the machine tool; then, take the average value of the depths of the two holes in each group collected, and use the least squares method to perform plane fitting on this value to calculate the fitting plane. This fitting plane can be approximately regarded as the neutral layer of the flow channel after vacuum diffusion welding. Calculate the two deflection angles between the fitting plane and the horizontal plane again, and use these two deflection angles and the translation distance of the fitting plane relative to the horizontal plane as the clamping correction values; finally, when performing machining clamping, correct the clamping of the vacuum diffusion welded microchannel cold plate according to the above three correction values, so as to machine a high-precision vacuum diffusion welded microchannel cold plate.

[0013] The embodiments of the present invention are as follows:

[0014] Before performing vacuum diffusion welding, according to the structural form of the microchannel cold plate 11, process multiple groups of measurement holes 10 in the margin removal area outside the dotted line frame of the upper plate 2 of the welding blank 12. The distribution of the measurement holes 10 satisfies the general statistical principle, as Figure 2 shown. The structural principle of each group of measurement holes is as Figure 1 shown, including 1. flow channel for welding, 2. upper plate, 3. measurement hole a, 4. measurement hole b, 5. margin removal area after welding, 6. reserved area after welding, 7. lower plate, 8. welding surface, 9. neutral layer plane of the flow channel. Each group of measurement holes consists of a flat-bottom hole (measurement hole a) flush with the bottom surface of the upper plate flow channel and a through hole (measurement hole b). Then, take the average value of the depths and the centers of the two holes in each group of holes collected, and use the least squares method to perform plane fitting on the value to approximately obtain the neutral layer plane of the flow channel. Finally, calculate the two deflection angles and the translation distance between the fitting plane and the original horizontal plane for clamping correction, and a microchannel diffusion welded cold plate can be accurately machined.

[0015] Suppose a total of n (n≥3) groups of measurement holes are collected. The depths of the two holes in the i-th (i≤n) group of holes are respectively Then the average value of the depths of the i-th group of holes is The projection coordinates of the centers of measurement hole a and measurement hole b in the horizontal plane are respectively Suppose Let (x i , y i , z i ) be the plane fitting data points, and the expression of the fitting plane is z = ax + by + c. According to the least squares method principle, it can be solved:

[0016]

[0017] Then the yaw angle θ and the roll angle φ between the normal vector of the fitting plane z = ax + by + c and the horizontal plane are respectively:

[0018]

[0019] Finally, the workpiece uses the fitting plane obtained above as the clamping reference. When the workpiece is machined and clamped, it is first translated -c in the z direction (a negative value indicates the opposite direction), and then deflected by the angles θ and φ accordingly. After the corrected clamping, a microchannel diffusion bonding water-cooled plate with uniform wall thickness distribution and high precision on both sides of the flow channel can be machined, thus avoiding the phenomenon of bulging on one side of the flow channel due to over-cutting.

Claims

1. A clamping and correction method for a vacuum diffusion bonded microchannel cold plate, characterized in that: First, before welding, multiple groups of measurement holes are machined in the surplus removal area of the workpiece to be welded. The measurement holes are distributed according to the structural characteristics of the welded part. Each group of measurement holes includes a through hole and a flat-bottomed hole with the bottom surface flush with the bottom surface of the flow channel. After welding, the depth data of each group of measurement holes are collected; then, the average value of the depth values of each group of measurement holes collected is taken, and the least squares method is used to perform plane fitting on the average value. The obtained plane is the approximate neutral layer of the flow channel after vacuum diffusion welding, and the translation distance and two deflection angles between the neutral layer of the flow channel and the horizontal plane are calculated; finally, when performing machining clamping, these two deflection angles and the translation distance of the fitting plane relative to the horizontal plane are used as the clamping correction values, and the vacuum diffusion welding microchannel cold plate is clamped and corrected through these correction values, so as to machine a high-precision vacuum diffusion welding microchannel cold plate.

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