Many foundry casting process in the production process may encounter casting box problems, once encountered this problem, will make casting size, shape and weight changes, resulting in serious defects castings, or even scrapped. Casting process is to raise the box is just pouring molten iron mold, due to hot metal dynamic pressure and static pressure is too large, improper loading and unloading box or weight weight or imbalance, so that the movement of the flask up, Surface outflow.
(1) characteristics
Casting parting surface height, width size increases, weight increase or reduce. Casting protruding parts of the leak, leaky parts were burr.
(2) the cause of lifting boxes
① iron weight is insufficient, place improper place, iron is not balanced or no pressure iron.
② bolt tightening, individual bolts are not fastened or fastened is not strong.
③ tightening the number of bolts used in the sand box or improper distribution, resulting in loose bolts.
④ bolts pressure plate strength is insufficient, long and thin, molten iron poured into the mold was bent when broken.
⑤ card is not jammed or tightly unbalanced, lack of strength to be broken.
⑥ ladle lift (hanging) too high or pouring too fast, add hot metal too fierce, so that the dynamic pressure and static pressure is too large.
⑦ cast iron after the water has not yet solidified, prematurely remove the iron, relax bolts and fixtures.
(3) prevention and treatment methods
① iron when the weight to pressure. According to the casting structure, size and weight, determine the weight of iron. General weight iron weight ratio of 1: 3 ~ 1: 4 or so. If the casting weight of 100kg, then the weight of iron to 300 ~ 400kg. It is better to tighten the condition with the bolt.
② pressure box, the pressure to balance the steady, the distribution should be reasonable, the gate near the pressure to be heavier. Note that there is a raised package at the bottom of the bar.
③ box with bolts fastening, and strive to tighten the bolt balance, do not unilaterally fastened to prevent the box tilt. Bolt should be re-checked after tightening to prevent tight tight tight.
④ Before using the bolts, you should first check the bolts nuts are loose, can not be used as much as possible, do not force to use. When used, the number, location and distribution of bolts are uniform and reasonable.
⑤ use the appropriate high strength bolts to prevent the pressure plate bending broken.
⑥ type box with a card when the card, the fixture to have a certain strength. When used, the card to balance the clamping box, can not unilaterally clamp, to prevent the box tilt. After the card is jammed, check the tour. At the same time, in the tight box, to tap the card, do not shake too large. Do not use the broken fixture.
⑦ According to the structural characteristics of castings, combined with the actual situation, control pouring pouring height and casting speed. When adding hot metal to slow, do not add too fast.
⑧ pouring, casting has not yet finished solidification, not too early to take the pressure iron or loose loose bolts, fixtures.
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