To solve the problem of casting loose defects
The most fundamental point is the "heat balance."
The method is:
(1) in the machine tool casting structure formed by the thick and hot section, the implementation of rapid solidification, artificially caused the machine tool casting temperature field of the basic balance. The use of internal and external cold iron, local use of large heat storage of zircon sand, chromite ore or special paint
(2) reasonable process design. The inner runner is located at the relatively thin wall of the machine tool, So that the earliest into the thick wall of the metal liquid before the first solidification, thin-walled after the solidification, so that the basic to achieve a balanced solidification. For wall thickness uniform machine tool castings, the use of multiple runners and out of the hole. The inner runner is mostly distributed and distributed so that the whole heat is balanced. Exhaust pores fine and more, that is, exhaust air from the heat effect.
(3) change the position of the inner runner
(4) the use of large heat storage materials, which is the use of EPC production of anti-wear products is extremely important! Chromite sand instead of quartz sand and other small heat storage of other sand species, will achieve good results, The
(5) low temperature fast burning, open pouring system. So that the metal liquid fast, smooth, balanced full of mold. This should be appropriate.
(6) ductile iron machine mold strength, surface hardness ≧ 90, sand box rigid, easy to eliminate shrinkage.
(7) need to take a riser when the first heat riser, and leave the hot section. If the riser on the hot section, will increase the riser size, the formation of "hot on the heating." Not bad, not only loose but also difficult to produce, but also produce concentrated shrinkage, but also reduces the production rate.
(8) mold tilting and alloying, are beneficial. Elimination of machine tool casting shrinkage defects is a complex understanding and implementation process. Should be "hot balance" as the basic principle, the mold body to do a scientific analysis, to develop a reasonable process program, move the appropriate shape of the appropriate materials, tooling and correct operation and standardization.