Shape
Preparation before modeling
Check whether the pattern is complete, whether there is damage or deformation, whether the movable block is complete, whether the positioning device is loose, whether the mold lifting device is firm, if necessary, take reinforcement measures, and the shape, size, quantity and position of the pouring riser pattern must meet the requirements of the process card. The shape, size and quantity of internal and external cold iron must meet the requirements of process card. Replace traceability marks such as heat number and date.
The molding bottom plate shall be slightly larger than the outer dimension of the sandbox, with a flat surface and sufficient strength to turn the sandbox over. The lifting shaft, lug, wall, etc. of the sand box shall be firm, and the matching of the locating pin shall be accurate.
Preparation of mold and core sand:
Molding sand production: 80% of the old sand, 20% of the new sand, 100% of the core sand, chromite sand is used for hot spot parts and important cores, 0.9-1.1% of the resin sand, 30% of the curing agent, and the upper limit of the core sand resin.
The strength of core sand is 0.5-0.6mpa, and the upper limit of core sand strength is taken.
Prepare modeling tools according to process requirements.
Sand box modeling
Shape
1) . according to the casting requirements, set the sand hook or tie racket on the sand box 10-20mm from the mold surface.
2) . the water glass sand molding and pattern shall be kept clean and clean. In order to avoid sticking the mold, the parting agent shall be frequently applied.
3) The thickness of molding sand is about 100-150 mm each time, and the groove and narrow ditch under the movable block are filled by hand first.
4) . at the junction of the cross gate and the straight gate opened on the parting surface, the gate nest shall be made. When the straight gate is higher than 1 m, the refractory brick shall be filled under it. For important parts, large parts of the sprue, transverse sprue, the sprue pipe joint of the internal sprue, the gap should be small, to be fixed well, to prevent deformation and position movement of the box.
5) . the box belt shall not hinder the contraction of the riser, and the distance between the inner side of the riser and the box belt shall not be less than 70mm.
6) . tie the vent hole and riser vent hole on the upper case.
7) . when there is no locating pin, make the accurate mark when closing the box.
Repair type
1) . when hammering the wood mold, the block shall be padded to prevent the damage of the pattern, and the looseness in all directions shall be even.
2) . after the formwork is lifted, carefully check the left live block and external cold iron. If the position deviation is found, it should be corrected and the pattern should be aligned in time.
3) . when treading on the mold surface to repair the mold, in order to prevent treading on the surface layer of the sand mold, paper or other things shall be padded.
4) The geometric shape and dimensional accuracy of the casting must be ensured during the mold repair.
5) Fillet and cut reinforcement according to process requirements.
6) . the core head shall make the air passage according to the air outlet direction to ensure the smooth air outlet.
7) . the paint shall be brushed evenly, and the vent holes of transverse gate, gate socket and concealed riser shall be brushed well.
Coremaking
1） Preparation before core making
Check whether the core box is complete, whether the structure is reasonable, whether the number and positioning of the movable block are correct, and use the card before core making
The core box shall be tensioned by the sub or bolt to prevent deformation of the string angle.
Check whether the core material meets the requirements.
Check the shape and structure of the core bone. The core bone shall have sufficient strength, not affect the contraction and ventilation, be easy to clean, and ensure the stable lifting of the core. The size of the core bone shall be determined according to the position in the core.
2） . core making
Sand core must have enough concession, so as not to affect the shrinkage and crack of the casting. For this reason, the thickness of the surface sand should be controlled when the core is built, and enough air holes should be left in the middle with loose material (foam, dry slag, coke, sawdust, dry sand, etc.).
It is not allowed to hit the edge of the core box, the wall of the core box and the protruding part of the core box when the Toon sand is used. The Toon sand must be tight. The groove and narrow ditch under the live block are not easy to be toon solid. First, the Toon sand shall be tightened by hand.
When the refractory brick is used as the gate or tie bar in the core box, the joint shall be blocked and the surrounding area shall be tightened.
Place the outer chill according to the requirements of process and casting, the distance between the outer chill shall be less than the length of the chill, and the outer chill on both sides of the rib plate shall be arranged crosswise.
On the surface of Toon sand, the position of lying platform or wedge should be accurate.
The core board must be paved with a layer of sand and a layer of newspaper when the working face is downward.
3） . core repair
When removing the core box, the block must be used to knock on the core box to prevent damage to the core box.
After disassembling the core box, carefully check the position of the movable block and the external cold iron. If there is any deviation, it should be corrected and the core box should be aligned in time.
The compactness of each part of the sand core shall be checked carefully, and the damaged and soft parts shall be repaired.
Fillet and cut reinforcement according to process requirements.
The lifting lug and vent hole shall be dug out for the sand core, and the core number shall be marked.
Check the size according to the process drawing, especially check whether the sand core is enlarged, skewed and deformed.
The paint shall be brushed evenly with a thickness of more than 0.5mm.
During the assembly of the two half sand cores, the shape and size of the sand cores shall be ensured, the air holes shall be unblocked, the joints shall be closely matched, the joints shall be firmly connected, the gap fortresses shall be strictly plastered, and the paint shall be applied before drying.
After drying, the sand core which has been placed for too long must be dried again. After drying, the strength of the sand shall be checked, and the sand without strength can not be used.