A Method for Eliminating Cracks in Gravity Casting

Abstract

The invention discloses a method for eliminating cracks generated in gravity casting, and belongs to the technical field of metal casting. The method comprises the following steps: a metal gap type pouring gate system is adopted; molten metal enters a gap pouring gate cylinder from a bottom pouring gate, and is injected in a thin-wall cavity through a gap gate; the gap pouring gate cylinder is guaranteed as a thermal section to eliminate a crack source in the gap gate; and insulation paint is brushed on the inner walls of the gap pouring gate cylinder and the gap gate, or refractory felt cylinders are positioned in the gap pouring gate cylinder and the gap gate, so that the smooth melt filling process is guaranteed. The metal gap pouring gate is adopted to replace a sand core gap pouring gate, recyclable and convenient to demold, solves the problem of easy generation of cracks in gap pouring gates of thin-wall parts, achieves the universal meaning on the casting process adopting the gap pouring gate system, and can effectively improve the pass percent of castings; and the insulation paint is brushed on the inner wall of the gap pouring gate cylinder, or the refractory felt cylinderis positioned in the gap pouring gate cylinder to guarantee smooth melt filling.

Description

technical field [0001] The invention belongs to the technical field of metal casting, and in particular relates to a method for eliminating cracks in gravity casting. Background technique [0002] At present, the gravity casting process is generally used to inject the molten metal into the mold under the gravity of the earth. In the gravity casting of aluminum alloy, in order to ensure the quality of the alloy structure, the casting process should try to conform to the sequence of solidification of the melt from theoretical considerations. , because the solidification temperature range of the alloy is wide, the casting process design is not good, and crack defects are prone to occur. [0003] In the existing gravity casting process, the gating system with slot runners is commonly used, which can realize the sequential solidification of the melt. However, the slotted runner that is often arranged adopts a sand core structure. After the aluminum water enters the thin-walled c...

AI Technical Summary

Problems solved by technology

However, the slotted runner that is often arranged adopts a sand core structure. After the aluminum water enters the thin-walled cavity of the slotted runner from the bottom runner, the thin-walled part at the far end solidifies first, and the vicinity of the slotted gate is the casting hot spot area. The final solidification, the shrinkage of successive solidification leads to cracking of thin-walled parts at the junction of slot gates, resulting in cracks of thin-walled parts at the gate of slotted runners

At the same time, the structure of the sand core makes demoulding inconvenient and the service life is short; moreover, the mold loading process is likely to cause defects in the sand core, resulting in an unsmooth filling process and reducing production efficiency; due to the heavy workload of sand core molding, time-consuming and energy-consuming , high production cost, not conducive to large-scale production

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