1、cast steel parts pouring system characteristics: cast steel characteristics of high melting point, poor fluidity, shrinkage, easy to oxidation, requiring a rapid and smooth filling of the metal liquid.
xinyuanzhu Group in the casting production found that the casting system has the following characteristics.
1.1 The body of cast steel shrinks a lot, and the castings are prone to defects such as shrinkage, shrinkage, cracking and deformation. Thick and wall thickness difference between the castings using the principle of directional solidification set pouring gate system, liquid nearly flow through the gate into the cavity, strengthen the ability of the gate to fill the shrinkage; for easy to produce cracks, deformation of the shell type castings, the internal sprue should be evenly distributed in the thin wall of the casting, and minimize the mechanical obstruction of the sprue to the casting.
1.2 Casting steel casting temperature is high, easy to oxidation, usually using leaky ladle casting. The slag blocking effect of leaky ladle pouring is good, the slag blocking effect of the pouring system is not high, so the cross-sectional area of the pouring system is large and open, do not need high slag blocking function, but should be fast and smoothly filled with the casting. Leakage package pouring pressure is high, easy to wash out the channel, therefore, the pouring system should strive for simple structure, strong impact resistance. The straight pouring channel of large and medium-sized castings and the horizontal and internal pouring channels of steel flow over 1T should be composed of refractory brick pipes. The pouring system of small cast steel parts can be composed of water glass, resin sand or all surface sand, and ensure sufficient strength.
2、Dimension calculation of casting system for cast steel parts
2.1 Dimensional calculation when pouring with ladle. When mass production of small cast steel parts, commonly used to turn ladle pouring. Generally use closed or semi-closed pouring system to strengthen the slag retention capacity. The cross-sectional ratio of the pouring system is: ΣA internal: ΣA horizontal: A straight = 1: (0.8~0.9): (1.1~1.2)
2.2 Dimensional calculation of pouring with leaky ladle Unlike the transfer ladle, the amount of metal liquid outflow during pouring with leaky ladle basically depends on the diameter of the hole at the bottom of the ladle. While the pouring system bears the steel falling from the bottom of the ladle, the pouring system itself does not have the role of controlling the flow rate. In actual production, determine the casting system is based on the size of the bottom hole diameter of the leakage package, first by the following table 1-11, find out the bottom hole diameter and flow rate while considering the number of holes, calculate the pouring time.
t=G/NnV ladle; where: t - pouring time (s); G - total weight of steel in the cavity (kg); n - number of injection holes per ladle (n); V ladle - pouring speed of steel (kg/s); N N - number of ladles to be poured simultaneously; 1-11 average value of different ladle diameters and pouring speed of molten steel ladle diameter d/mm 30 35 40 45 50 55 60 70 80 100 pouring speed V=kg/s 10 20 27 42 55 72 90 120 150 195 The suitability of the calculated pouring time can be verified by the rising speed of the steel in the cavity, V
V=h/t; where: V-rising speed of liquid in the cavity (mm/s); h-pouring position of the casting (mm) (when calculating the rising speed of the steel for inclined pouring, the height h should be taken as the casting height plus 1/2 of the inclined height); t-pouring time (s) When the calculated rising speed V is less than the value in Table 1-12, the package hole of large size can be used or the number of package holes can be increased. When conditions allow, the pouring can also be tilted, the tilt height is determined by the size of the sand box, but the maximum tilt should not exceed 300mm.
Minimum allowable rise speed of steel in the cavity Casting weight/t Casting structure <5 ＞5～15 ＞15～35 ＞35～65 ＞65～100 Complex: 25 20 16 14 12 Medium: 20 15 12 10 8 Simple: 15 10 8 6 5
According to the selected package hole, calculate the cross-sectional area and determine the total cross-sectional area of each sprue in proportion to the following ratio: A hole: ΣA inside: ΣA across: ΣA straight = 1: (1.8 to 2.0): (1.8 to 2.0): (2.0 to 2.5) Calculate the total cross-sectional area of each sprue and determine the cross-sectional area, geometry and geometry of each sprue according to the shape, structural size and production conditions of the casting. Geometry and dimensions of each sprue are determined according to the casting shape, structural size and production conditions.
2.3 When pouring with leaky ladle, the pouring speed of package hole V package is closely related to the height of the pressure head of the steel in the pouring ladle. The high pressure head results in fast pouring speed; the low pressure head results in small pouring speed. Therefore, when the steel in a ladle needs to pour several different castings continuously, the casting with faster rising speed of the steel should be poured first. In order to meet the requirements of the rising speed, the diameter of the package hole should be calculated according to the average pressure head of the steel in the pouring ladle when pouring the last casting, in order to meet the requirements of the last casting on the rising speed. For the castings poured in front of you can control the plug lever to open the degree of the package hole to control the rising speed of each casting steel.
Xinyuanzhu Group specializes in the production of Ductile iron castings, Pig iron gray iron casting, Steel casting, Brass Casting, Malleable Iron Casting, and undertakes batch casting processing of castings. Welcome guests to cooperate with pictures or samples.