Improvement of fin image technology based on anti deformation principle
Fin heat sink is mainly used for cooling and heat dissipation of power electronic equipment, which is widely used in rail transit, wind power generation and other fields. At present, there are three main assembly processes of heat sink base plate and fin: extrusion riveting, low temperature welding and gluing. In the process of extruding and riveting insert, the base plate will be deformed after being stressed, which will seriously affect the subsequent processing. At this time, oil pressure will be used to ensure the flatness of the base plate. If the base plate deforms seriously, some fins will be loose after oil pressure. For a long time, extruding and riveting deformation is a difficult problem affecting the quality of fin heat sink products.
The laser welded composite fin tube, Murphy experts takes the fin heat sink of a certain type locomotive as the cutting point. Aiming at the phenomenon of thin base plate design, serious deformation and uneven fin spacing after inserting, through understanding the field operation, cutting tool and base plate processing state, it finds out many factors that lead to product deformation due to direct connection, and thus conceives the improvement method. Based on the improvement of cutting tool and The new technology combined with oil pressure reverse deformation of base plate provides an important reference for subsequent product processing.
Process improvement
The original process is as follows: base plate cutting, cleaning, inlay, oil pressure leveling, and subsequent process. In order to prevent the back shape of the base plate, the base plate shall be subject to oil pressure reverse deformation before inserting. The process route is changed to: cutting groove of the base plate - oil pressure reverse deformation. Clean, insert and calibrate. Subsequent operations (unchanged}.
Tool design improvement
From the field operation, it was found by Murphy experts that the tool used before was warped upward when it was forced, resulting in the irregular curve phenomenon of left and right swing of the machining path, so the tool bar and blade were redesigned. After use, the new cutter overcomes the unreasonable structure of the original cutter. After machining, the knife mark is clear and the cutting cut is even. The back deformation of the unnecessary cutter is greatly reduced, which is conducive to reducing the bulge deformation of the whole part. The comparison of the new and old cutters is as follows:
Old tool machining: after the tool is fed in the vertical direction, the back face is deformed greatly. The deformation of the front near the direction of the insert is less than that of the back, which is not conducive to the compression of the fins. The unfavorable deformation of the back increases the accumulation of internal stress.
After the tool is fed vertically, the back of the tool is vertical to the surface of the substrate, and the backward deformation is reduced. As the angle of the tool is different from that of the old tool, the deformation required in the front near the direction of the insert is increased, which is more conducive to the compression of the fins, and is conducive to reducing the deformation of the whole substrate after the insert.
Plate reverse deformation operation
Because when the heat sink is riveted, the base plate of the heat sink will be deformed towards the non channel side due to the stress. Through the experiment, we can use the principle of reverse deformation to make the base plate deform towards the channel surface in advance, and then use the internal stress during the subsequent extrusion riveting to make the base plate just return to flatness. The specific operation is as follows: the parts with grooves are pressed with oil press before inlay, and the square steel bar is used to press down into V-shape in the part seam, so as to produce plastic deformation of the parts, and the depth is controlled within a certain range, and the depth is measured with knife edge ruler and feeler gauge.
评论
发表评论