Common Process Structure of Parts in Casting Processing
Release time:
2020-05-13
1. Forging fillet
In order to facilitate casting modeling, prevent sand falling from the corner of the sand mold when starting from the sand mold and wash the corner during pouring, and avoid forging defects such as cracks, loose organization and shrinkage holes at the corner of the casting, the intersection of adjacent surfaces on the casting should be rounded. For pressed plastic parts, the rounded corners can ensure that the raw materials fill the die and facilitate the parts to be taken out of the die.
Forging fillet radius generally take 0.2-0.4 times the wall thickness, can be found from the relevant standards. The size of the fillet radius of the same casting should be the same or as close as possible.
2. Tilt of formwork lifting
When modeling, in order to facilitate the wood mold out of the sand mold, the inner and outer walls of the casting are permanently calculated along the direction of the mold, which is called the mold slope (or forging slope). The inclination of formwork is generally 1:100-1:20. When expressed by angle, the appearance of manual modeling wood is 1-3, the appearance of metal is 1-2, and the appearance of mechanism modeling metal is 0.5-1.
Because there are forged fillets at the intersection of the casting surface, the intersection line of the surface becomes less obvious. In order to distinguish different surfaces when looking at the figure, the intersection line in the figure should still be drawn. Such intersection line is usually called transition line. The drawing method of the transition line is basically the same as that of the intersecting line without rounded corners.
3. Casting wall thickness
In order to ensure the forging quality of castings and avoid the occurrence of loose organization and shrinkage cavity outside the wall thickness and cracks between thin and thick phases due to different cooling and crystallization rates due to uneven wall thickness, the wall thickness of castings should be uniform or gradually changed to prevent sudden reversal of wall thickness and local hypertrophy. The change of wall thickness should not be too large, so the transition slope can be set at the intersection of the two walls. Its wall thickness is sometimes not noted in the figure, but is noted in the technical request.
In order to facilitate mold making, modeling, sand cleaning, removal of gate and riser and machining, the shape of the casting should be simplified as much as possible, the shape should be as straight as possible, and the inner wall should reduce the concave and convex structure. The casting is thick and thick and prone to cracks, shrinkage and other forging defects, but thick and thin and make the casting strength is not enough. In order to prevent the influence of thickness reduction on strength, reinforcing ribs can be used to compensate.
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