Strip plate section form for machining T-section metal strips

Abstract

The invention relates to a strip plate section form for machining T-section metal strips. The form is in holohedral symmetry vertically and horizontally; and a transitional area with gradually changed thickness is formed between a thin material t2 and a thick material T2, so that the uniformity is effectively improved when the thick and thin materials are cooled, and local internal stress generated when a thick and thin material interface is solidified and contracted can be reduced or eliminated when the materials are solidified and contracted. Compared with the prior art, the invention has the advantages that cracks of strip plates are reduced or eliminated, the yield is improved, the stress state of a mold is improved, the wear of the mold is reduced and the service life of the mold is prolonged.

Description

technical field [0001] The invention relates to a strip blank sectional shape for processing a T-shaped cross-section metal strip, in particular to a strip blank cross-sectional shape for processing a T-shaped cross-section copper alloy strip for power transistors. Background technique [0002] The cross-section of the T-shaped cross-section copper alloy strip used for power transistors is usually formed by two specifications: thin and thick. The thin material is used as a lead for circuit connection, and the thick material supports the chip and heat dissipation. The common section is shown in figure 1 , is a T-shaped section, the middle is a thick material, which is a trapezoidal protrusion, and the two sides are thin materials of equal size. In order to meet the requirements of high-speed punching dies for frame punching, the dimensional tolerance and surface roughness of the T-shaped section strip Degree, side bending, residual internal stress, etc. have very strict techn...

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Problems solved by technology

[0008] The rectangular cross-section strip used in method 1 is usually obtained through multiple processes such as ingot hot rolling, cold rolling, and slitting. In the forming of T-shaped section, the processing process becomes complicated due to the difference in processing rate between thick material and thin material

And method 2 is to use the cross-sectional shape similar to the finished product cross-section as the mold shape to continuously cast T-shaped billets or extruded T-shaped billets. The process is short and the project investment is low. In the subsequent forming of the T-shaped section, the subsequent processing becomes simple due to the basically the same processing rate of the thick material and the thin material. Inhomogeneous, internal stress will be generated locally at the junction of thick and thin materials during solidification and shrinkage. When the internal stress is greater than the tensile strength of the material, it will cause small internal cracks that cannot be recognized by the naked eye. In severe cases, obvious cracks will appear. The internal cracks that cannot be recognized by the naked eye will be elongated and appear intermittent long cracks during cold pressure processing, so that the product will be scrapped. At the same time, judging from the shape of the blank ( figure 2 ), due to the excessive size of the step at the junction of thick and thin materials and the asymmetry of the overall shape, the overall force of the mold is uneven and the local wear is too large, which leads to early failure and affects the service life of the mold

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