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Knowledge - Operating Instructions for Casting Box and Pouring

Aug. 18, 2020

Shengjian Prosperity Machinery Parts Co., Ltd.

1 Close the box

(1) Be familiar with the process drawings and related documents of castings.

(2) Check whether the sand molds and mud cores are overblown or not hard, and the damaged parts should be repaired. Sand molds and mud cores that have been parked for a long time after hardening are strictly prohibited to use if their surfaces are severely whitened.

(3) Remove the floating sand and debris on the surface of the cavity, gating system and mud core, and cover the straight gate.

(4) The core is laid in a reasonable order according to the cross lines and related center lines to ensure the size and skin thickness of each part of the casting.

(5) The gap between the mud cores is fortified, the core hanging place is repaired and dried, and the multi-layer mud cores should be covered layer by layer to prevent the sand from falling into.

(6) The hanging core should be fastened to the upper box with iron wire or special screw hook, and the drape should be stuffed.

(7) The air outlet direction of the mud core is divided into upper, middle and lower three types according to the mold structure. The air passage must be unblocked. The air outlet from the upper part should be combined with the air outlet of the loose layer. The air outlet from the bottom should be shaped like a pit. Eyes open into the pit exhaust layer.

(8) The mud core must be well secured, the core support must be evenly distributed, and the strength must be sufficient. The mud core with greater buoyancy must use a hard top, and the top of the mud core with a riser that is not easy to fix.

(9) The inner cooling iron should be clean and rust-free when placed according to the process requirements, and the fixing should be firm.

(10). The core of the pit core is connected to the gate and it is hit and flattened, and the parts that are easy to expand should be backed by the shim or the box ring.

(11) Pay attention to safety when turning the box to prevent damage to the sand mold. When it is necessary to stand under the box to repair the mold, the four corners of the sand box must be stabilized, and the hanging box repair is prohibited.

(12) The upper box vent (including the dark riser vent) is surrounded by sand that is higher than the box surface, and a layer of dry sand is used, and the open riser is 50-100 mm higher than the pouring height.

(13). Before closing the box, remove the floating sand in the casting and gate, check whether the inner cooling iron and mud core support are loose, and whether the air passage is unblocked.

(14) Check the box before closing the box to check whether there is any deviation of the box, whether the thickness of the skin is consistent, whether the gate and the air hole are tight, whether the air hole is correct, whether the mold is crushed, or sanded.

(15) Put the mud core support on the core around the parting surface of the inspection box, asbestos rope around the gate and air hole according to the thickness of the skin.

(16) When closing the box, the upper box should be hung flat, and the box and the pit shape should be aligned manually with the box closing signs.

(17) The shape of the box must be tightly fastened, and the opposite part of the box must be sealed with molding sand to prevent fire.

(18) If the cavity is deep or the bottom is thin, the shape of the box should be stabilized. The bottom should be flat and padded, and the box should not be moved after closing.

(19). The four corners of the upper box of the pit shape should be leveled, and the surrounding shim should be bumped tightly. The gate should be made according to the requirements of the casting.

(20) The weight of the weight should be sufficient, the placement should be stable, the distribution should be even, the back should be tight before pouring, and the back should be even. The contact surface between the support point and the sand mold during the dark pressing is well cushioned with steel plates to prevent the contact area from being too small to cause drift.

(21). When the upper box is covered with a core or two sand boxes are used for butt joints, iron sheets (or iron plates) should be used at the butt joints, and the joints must be well plugged and pressed tightly. The opposite part of the big box should be firmly backed with the weight.

(22) The time interval between closing and pouring is as small as possible. Generally, it is closed on the same day and pouring on the same day. It should be opened for inspection after two days.

(23) After closing the box, check whether the cavity is clean and whether the inner core is crushed.

(24) Dry the cavity for more than 8 hours before pouring.

2 pouring

(1) Determining a special person to direct the pouring. Before pouring, the commander should first understand the material of the furnace, the weight of molten steel, the size and quantity of the ladle holes, the quantity and weight of the castings to be poured, the mold layout and the pouring method. When there are more than one package, the molten steel should be measured in time to avoid insufficient pouring. Resolute implementation must be made if the process regulations require supplementary pouring of the riser.

(2) Arrange the cups of the box shape in a straight line as far as possible, and gather them together with the same material.

(3) Prepare heat preservation agent, air-entraining material, and match pouring table if necessary.

(4) A comprehensive inspection should be carried out before pouring in the pit, whether there is floating sand in the riser, whether the weight is well backed, and whether the pouring workers are safe to operate.

(5) Before pouring, pouring the crown block, crossing flat cars and other equipment should be inspected by special personnel, the site should be cleaned up, and the pouring ground should not have water, flammables, etc.

(6) The personnel participating in the pouring should be equipped with labor protection supplies, and the non-pouring personnel should leave the pouring site during pouring.

(7) When pouring castings, according to the tapping temperature and the required pouring temperature, it should be calmed for a certain period of time, and the pouring temperature can be reached before pouring.

(8) The ladle must be stopped and align the sprue cup. The bottom of the ladle is about 250 mm away from the sprue cup. The items under the ladle hole cannot fall into the sprue.

(9) At the beginning of pouring, bleed air immediately to prepare the pit where the remaining molten steel is poured, so that the remaining molten steel can be dumped easily.

(10) When pouring small and complex parts to the parting surface, flow slowly, and then pouring at full speed. When the upper box of large parts is large, the molten steel surface should be poured to the riser height of 50~100 mm when the molten steel flow rate should be reduced. , Pouring to the specified height, and then point pouring the riser. If the riser is less than 300mm, it can be poured through the straight nozzle for 1~2 times. The riser is greater than 300~700mm. When the height of the pouring riser is 1/2 or not less than At 300 mm, it can be poured 3 to 4 times with a half-opened hole through the straight nozzle. Sprinkle insulation agent afterwards. In addition, the castings that need to fill the riser are determined according to the process.

Casting wall thickness (mm)When removing the weight after pouring (minutes)
40~8015~25
81~15025~40
151~30040~60
>30060~120

(11) Remove the weight load time:

Note: (1), the parts of the supplementary pouring riser are recorded when the riser is filled.

(2) If the wall thickness is uneven and there are local thick areas, the time should be extended as appropriate, generally not more than 3 hours. If there are two or three refilling of the riser, the time is calculated from the last one.

3 Record

(1) Marine castings need to record: casting name, casting number, furnace number, material, pouring time. And the iron plate will mark the recorded information on the poured sand box.

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