Suggestions on Casting Large Steel Castings from Furan Resin Self-hardening Sand
1. Introduction and use of molding sand for steel castings
Surface sand: mainly use chromite sand as raw material, after adding liquid material for stirring, the sand used on the surface of the mold is called surface sand. The main function is high strength after hardening, good heat resistance, and has
certain thermal insulation. Due to the high cost of chrome ore, it is generally used in the parts that are in direct contact with molten steel; its thickness is controlled at 50mm-70mm during use; a relatively large amount of liquid material is added to ensure the hardening strength of its surface.
Back sand: mainly use silica sand as raw material. After adding liquid material for stirring, it is used behind the surface sand and in the filling space between the sand boxes. The main function is to fix and support, with a certain thermal insulation effect. The back sand has a high recovery rate and a relatively low cost; the back sand uses less liquid material than the face sand, and only needs a certain support strength.
2. Recycled sand
The surface sand and back sand after recovery are called regenerated chromite sand and regenerated silica sand, which are collectively referred to as regenerated sand. In the actual production process, most of the reclaimed sand is used, which is very stable for the quality of castings.
Qualitatively speaking, it is necessary to add a part of new sand to the regenerated sand to neutralize the performance and strength lost due to the separation process of the chromite sand. Generally, the amount of new sand added for regenerated silica sand is 5%, and the amount of new sand added to regenerated chrome ore is 5%. 20%. From the perspective of sustainable production, it also reduces cost waste, thus stabilizing the quality of molding sand and ensuring good quality casting products.
3. Sanzhuji suggested sand operation method
The molding sand is covered on the surface of the mold, and after hardening, the mold is taken out to form a usable sand core. There are strict requirements for the sand strength and surface quality of the semi-finished sand core. The part of the product is in direct contact with molten steel, and its strength and surface quality are strictly required. Only by operating in accordance with the process design requirements will the defects of sand sticking on the surface of the product castings be avoided as much as possible in the subsequent process.
3.1 Process requirements The thickness of the surface sand is guaranteed to be 50mm~70mm
3.2 The compactness of the surface sand is required to be above 88HR (use a dry hardness tester to measure the compactness of the molding sand)
3.3 The surface sand compaction operation mainly relies on the employees'''''''' hands to slap and compact during the process of surface sand flow; for the parts that cannot be reached by human hands, compaction tools are required for compaction.
3.4 In the process of quicksand, avoid the surface sand flowing directly against the surface of the mold, so as to prevent the process of quicksand from damaging the surface of the mold and causing the phenomenon of semi-finished sand sticking to the mold.
3.5 The surface sand flow process should be less flowing and more compact. Make sure that the part of the surface sand covering the surface of the mold has been tapped and tightened in place by hand or a tightening tool, to ensure that the strength of the semi-finished product meets the process requirements, avoid virtual pits or places that are not tightened in place, and prevent sand sticking in the subsequent sequence.
The above operation methods are formulated to control the surface quality of castings. The main purpose is to reduce the cost waste of subsequent casting repairs and ensure the delivery period. The most important thing in the molding process is the compaction of the sand core. At present, in the production process of large-scale steel castings, automatic compaction operations cannot be realized, and the operating skills of personnel will also directly affect the quality of the castings. Due to the difference in the structure and material of the castings, the above methods are common to general steel castings. However, for castings with complex structures and high alloys, the above operations cannot meet the requirements.
4. Sanzhuji''s anti-stick sand operation requirements for castings with complex structures and high alloys.
For castings made of high-alloy steel, due to their special material, more alloying elements are added, and the pouring temperature of high-alloy castings is higher than that of ordinary castings, so the surface of the castings that are boxed in the subsequent sequence will stick to sand. more serious.
4.1 For high alloy castings, increase the thickness of the surface sand in the use of molding sand, from the original 50mm~70mm to 100mm~200mm, to improve the high temperature resistance of the molding sand.
4.2 Increase the compaction process and place sand-blocking cold iron in some areas with the most serious sand sticking, so that it can quickly cool down and solidify to avoid sticking sand.
4.3 In the process of molding quicksand of high alloy products, place an air rope to accelerate the rapid discharge of combustible gas in the molding sand and quickly reduce the temperature of the molding sand.
4.4 For the parts that are easy to stick to the sand, increase the brushing times on the brushing requirements, so that the thickness of the coating is about 1mm~1.5mm, so as to improve the heat resistance of this area.
5. Sand sticking is a relatively well-controlled defect in the casting production process. In theory, each casting will have a more or less sticky sand phenomenon due to factors such as different structures and different heating. The ratio of the curing agent and the adjustment of the amount of new sand added, we have obtained a relatively stable molding sand, which can effectively control or reduce the sand sticking of the casting, thereby improving the appearance defects of the casting surface and reducing the subsequent cleaning. The workload indirectly improves the overall quality of the casting.
Qingdao Sanzhuji Equipment Manufacturing Co., Ltd. specializes in the production of Green Sand Molding Line,Self-hardening sand molding line,foundry machines,Sand molding machine,Sand casting equipment,sand mixer,GS high efficiency rotary mixer,Resin sand mixer,no-bake resin sand mixer,Jolt squeeze molding machine/Jolt-squeezing moulding machines,Multi- Piston Moulding Machine/Hydraulic multi-piston moulding machine,sand casting molding machine,sand reclamation equipment，foundry molding machine,flaskless moulding machine,shot blasting machine,dust collector,according to the amount of old sand recovered Carry out plan customization, and provide sand reclamation equipment installation, commissioning, and training. Welcome guests to visit the factory.
Surface sand: mainly use chromite sand as raw material, after adding liquid material for stirring, the sand used on the surface of the mold is called surface sand. The main function is high strength after hardening, good heat resistance, and has
certain thermal insulation. Due to the high cost of chrome ore, it is generally used in the parts that are in direct contact with molten steel; its thickness is controlled at 50mm-70mm during use; a relatively large amount of liquid material is added to ensure the hardening strength of its surface.
Back sand: mainly use silica sand as raw material. After adding liquid material for stirring, it is used behind the surface sand and in the filling space between the sand boxes. The main function is to fix and support, with a certain thermal insulation effect. The back sand has a high recovery rate and a relatively low cost; the back sand uses less liquid material than the face sand, and only needs a certain support strength.
2. Recycled sand
The surface sand and back sand after recovery are called regenerated chromite sand and regenerated silica sand, which are collectively referred to as regenerated sand. In the actual production process, most of the reclaimed sand is used, which is very stable for the quality of castings.
Qualitatively speaking, it is necessary to add a part of new sand to the regenerated sand to neutralize the performance and strength lost due to the separation process of the chromite sand. Generally, the amount of new sand added for regenerated silica sand is 5%, and the amount of new sand added to regenerated chrome ore is 5%. 20%. From the perspective of sustainable production, it also reduces cost waste, thus stabilizing the quality of molding sand and ensuring good quality casting products.
3. Sanzhuji suggested sand operation method
The molding sand is covered on the surface of the mold, and after hardening, the mold is taken out to form a usable sand core. There are strict requirements for the sand strength and surface quality of the semi-finished sand core. The part of the product is in direct contact with molten steel, and its strength and surface quality are strictly required. Only by operating in accordance with the process design requirements will the defects of sand sticking on the surface of the product castings be avoided as much as possible in the subsequent process.
3.1 Process requirements The thickness of the surface sand is guaranteed to be 50mm~70mm
3.2 The compactness of the surface sand is required to be above 88HR (use a dry hardness tester to measure the compactness of the molding sand)
3.3 The surface sand compaction operation mainly relies on the employees'''''''' hands to slap and compact during the process of surface sand flow; for the parts that cannot be reached by human hands, compaction tools are required for compaction.
3.4 In the process of quicksand, avoid the surface sand flowing directly against the surface of the mold, so as to prevent the process of quicksand from damaging the surface of the mold and causing the phenomenon of semi-finished sand sticking to the mold.
3.5 The surface sand flow process should be less flowing and more compact. Make sure that the part of the surface sand covering the surface of the mold has been tapped and tightened in place by hand or a tightening tool, to ensure that the strength of the semi-finished product meets the process requirements, avoid virtual pits or places that are not tightened in place, and prevent sand sticking in the subsequent sequence.
The above operation methods are formulated to control the surface quality of castings. The main purpose is to reduce the cost waste of subsequent casting repairs and ensure the delivery period. The most important thing in the molding process is the compaction of the sand core. At present, in the production process of large-scale steel castings, automatic compaction operations cannot be realized, and the operating skills of personnel will also directly affect the quality of the castings. Due to the difference in the structure and material of the castings, the above methods are common to general steel castings. However, for castings with complex structures and high alloys, the above operations cannot meet the requirements.
4. Sanzhuji''s anti-stick sand operation requirements for castings with complex structures and high alloys.
For castings made of high-alloy steel, due to their special material, more alloying elements are added, and the pouring temperature of high-alloy castings is higher than that of ordinary castings, so the surface of the castings that are boxed in the subsequent sequence will stick to sand. more serious.
4.1 For high alloy castings, increase the thickness of the surface sand in the use of molding sand, from the original 50mm~70mm to 100mm~200mm, to improve the high temperature resistance of the molding sand.
4.2 Increase the compaction process and place sand-blocking cold iron in some areas with the most serious sand sticking, so that it can quickly cool down and solidify to avoid sticking sand.
4.3 In the process of molding quicksand of high alloy products, place an air rope to accelerate the rapid discharge of combustible gas in the molding sand and quickly reduce the temperature of the molding sand.
4.4 For the parts that are easy to stick to the sand, increase the brushing times on the brushing requirements, so that the thickness of the coating is about 1mm~1.5mm, so as to improve the heat resistance of this area.
5. Sand sticking is a relatively well-controlled defect in the casting production process. In theory, each casting will have a more or less sticky sand phenomenon due to factors such as different structures and different heating. The ratio of the curing agent and the adjustment of the amount of new sand added, we have obtained a relatively stable molding sand, which can effectively control or reduce the sand sticking of the casting, thereby improving the appearance defects of the casting surface and reducing the subsequent cleaning. The workload indirectly improves the overall quality of the casting.
Qingdao Sanzhuji Equipment Manufacturing Co., Ltd. specializes in the production of Green Sand Molding Line,Self-hardening sand molding line,foundry machines,Sand molding machine,Sand casting equipment,sand mixer,GS high efficiency rotary mixer,Resin sand mixer,no-bake resin sand mixer,Jolt squeeze molding machine/Jolt-squeezing moulding machines,Multi- Piston Moulding Machine/Hydraulic multi-piston moulding machine,sand casting molding machine,sand reclamation equipment，foundry molding machine,flaskless moulding machine,shot blasting machine,dust collector,according to the amount of old sand recovered Carry out plan customization, and provide sand reclamation equipment installation, commissioning, and training. Welcome guests to visit the factory.
