| 摘要 |
Formation of a double sandwich braze joint between the steel body of a bit and a carbide insert tip disposed in a groove formed across the body is facilitated by a butterfly-type shim having an array of perforations defined through its bottom wall and side walls and generally across a mid-section region of the shim. The shim also has opposite end regions where the bottom wall and side walls are solid and free of perforations. The shim side walls are disposed between the side surfaces of the bit body and insert tip and the shim bottom wall is disposed between the bottom surfaces of the bit body and insert tip such that the shim mid-section region containing the perforations is disposed adjacent central regions of the bit body and insert tip and the shim solid perforation-free opposite end regions are disposed adjacent opoposite end regions of the bit body and insert tip. The perforations of the shim mid-section region allow flow of greater amounts of braze to the corresponding adjacent central regions of the bit body and insert tip than to the opposite end regions thereof so that the double sandwich braze joint produced between the bit body, insert tip and shim is nonuniform with respect to braze thickness across the joint. The braze is thicker at the central regions of the bit body and insert tip and mid-section region of the shim and thinner at opposite end regions of the bit body, insert tip and shim.
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