Suggestions for sand tire boxing and casting
1. Close the box
1.1 Familiar with the process drawings and related documents of castings.1.2 Check whether the sand molds and mud cores are over-blown and 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.
1.3 Remove the floating sand and debris on the surface of the cavity, gating system and mud core, and cover the direct gate.
1.4 The core is laid in a reasonable order according to the crosshairs and related center lines to ensure the size and thickness of each part of the casting.
1.5 The mud core gap is fortressed, the core hanging place is repaired and dried, and the multi-layer mud core should be covered layer by layer to prevent sand from falling into it.
1.6 The lifting core should be fastened to the upper box with iron wire or special screw hooks, and the drape should be stuffed.
1.7 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. In the pit exhaust layer.
1.8 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 should use a hard top, and the top of the mud core with a riser that is not easy to fix.
1.9 The inner cooling iron should be clean and free of rust when placed according to the process requirements, and the fixing should be firm.
1.10 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 with a shim or the box ring should be hit.
1.11 Pay attention to safety when turning over 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.
1.12 The upper box vent (including the dark riser vent) is surrounded by sand hitting the surface of the box, and a layer of dry sand is used, and the open riser is 50-100 mm higher than the pouring height.
1.13 Before closing the box, remove the floating sand in the casting and gate, check whether the inner cooling iron and the mud core support are loose, and whether the air passage is unblocked, etc.
1.14 Check the box before closing the box, check whether there is any deviation, whether the thickness of the skin is consistent, whether the gate, the air hole are tight, whether the air hole is correct, whether the mold is crushed, or sanded.
1.15 Place the core support around the parting surface of the inspection box, asbestos ropes around the gate and air holes according to the thickness of the skin.
1.16 When closing the box, the upper box should be hoisted flat, and the box and the pit shape closed box signs should be aligned manually.
1.17 The shape of the box must be fastened well, and the counterpart of the manual box must be sealed with molding sand to prevent fire.
1.18 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 the box is closed.
1.19 The four corners of the upper box of the pit shape should be leveled up, and the surrounding sills should be bumped tightly, and the gate should be made according to the requirements of the casting.
1.20 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. During the dark pressing, the contact surface between the supporting point and the sand mold is cushioned with steel plate to prevent the contact area from being too small to cause drifting.
1.21 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 opposite seams. The seams should be well plugged and pressed tightly. The opposite part of the big box should be firmly backed with the weight.
1.22 The time interval between closing the box and pouring is as small as possible. Generally, it is closed on the same day and poured on the same day. It should be opened for inspection if it exceeds two days.
1.23 After closing the box, check whether the cavity is clean and whether the inner core is crushed.
1.24 Dry the cavity for more than 8 hours before pouring.
2. Casting
2.1 Determine a person to direct the casting. Before casting, the commander should first understand the material of the furnace, the weight of the 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, etc. When there are multiple pieces in 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.
2.2 Arrange the cups of the box shape as much as possible in a straight line and gather them together with the same material.
2.3 Prepare heat preservation agent, air-entraining material, and match casting table if necessary.
2.4 A comprehensive inspection should be carried out before casting in the pit, whether there is floating sand in the riser, whether the weight is well backed, and whether the casting workers are safe to operate.
2.5 Before casting, cast cranes, crossovers and other equipment should be inspected by special personnel, the site should be cleaned up, and there should be no water, flammables, etc. on the casting floor.
2.6 Participants in casting should be equipped with labor protection supplies, and non-casting personnel should leave the casting site during casting.
2.7 When casting castings, according to the tapping temperature and the required casting temperature, it should be calmed for a certain period of time, and the casting can be carried out when the casting temperature is reached.
2.8 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.
2.9 At the beginning of casting, bleed air immediately to prepare the pit where the remaining molten steel is poured, so that the remaining molten steel can be dumped easily.
2.10 When small and complex parts are cast to the parting surface, flow slowly, and then cast at full speed. When the upper box of the large part is large, the molten steel surface should be poured to the riser height of 50 to 100 mm. The flow rate of the molten steel should be reduced. Specify the height, and then point 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 riser is 1/2 or not less than 300mm , It can be poured 3~4 times with a half-open bag hole through the straight nozzle. Sprinkle insulation agent afterwards. In addition, the castings that need to be added to the riser are determined according to the process.
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