What Are The Principles That Should Be Followed For The Casting Position Of Mechanical Castings
What are the principles that should be followed for the casting position of mechanical castings
Based on the research and production experience of the solidification theory of mechanical castings, the principle should be taken into account when determining the pouring position.
1, an important part of the mechanical casting should be placed in the lower part. The lower metal of the mechanical casting is solidified under the static pressure of the upper metal and is contracted and compact.
2, important processing surface should be down or upright state. Experience shows that pores, non-metallic inclusions and other defects appear in the upward surface, and the downward surface or side facade is usually relatively smooth, the possibility of defects is small, the individual processing surface must be upward, should be appropriate to enlarge Processing margin to ensure that after processing does not appear defects. A variety of machine tool bed surface is the key surface, not allowed to have trachoma, pores, slag holes, cracks and shrinkage and other defects, and requires the organization dense and uniform, to ensure that the hardness value within the specified range.
3, so that the mechanical plane of the large plane down or tilted. For large flat castings, tilting can be used in order to increase the metal surface of the rising speed, to prevent sand scar scar defects. Tilt pouring, according to the sand box size, H value is generally controlled in the 200 ~ 400mm range.
4, should ensure that the casting can be filled. For castings with thin-walled parts, the thin-walled parts should be placed in the lower half or placed below the pouring track to avoid defects such as pouring or coldting.
5, should be conducive to the filling of mechanical casting. For the shrinkage of the alloy or the thickness of the casting structure is uneven and prone to shrinkage, shrinkage casting should give priority to the conditions of the order of solidification, to facilitate the placement of risers and play the role of riser.
6, to avoid hanging sand, hanging sand or cantilever sand core, easy under the core, box and test. Experience shows that hanging sand in the box, pouring easy to collapse. It is inconvenient to place the hanging core on the upper half. Cantilever sand core is not stable, easy to skew under the action of metal buoyancy, it should try to avoid. In addition, to take care of the core, the box, the convenience of inspection.
7, should be the box position, casting position and mechanical casting cooling position consistent. Flip the mold is not only large amount of labor, but also easy to cause sand core movement, out of sand, and even fire and other defects.