1、 Purpose
Strengthen the inspection and control of the quality of the molding process, improve the operation quality of the molding process, and improve the surface finish and dimensional accuracy of the sand casting .
2、 Scope of application
This document is applicable to the preparation of molding and core making in each process of resin sand production in casting workshop. Quality control of production.
3、 Preparation for production
1. The operator shall be familiar with the casting process of the produced castings, and prepare cold iron, riser and special molding sand according to the process requirements. The team leader and package team technician are responsible for this work.
2. The resin and curing agent for production can only be used after passing the incoming inspection: in case of failure, deterioration and other phenomena, it shall be stopped.
3. Resin sand recycled sand shall be checked for sand temperature and micro powder content, 1-2 times a day, and once a week as appropriate. It can only be used after passing the inspection. The molding sand tester shall be responsible for this work and fill the test results in the corresponding quality records; In case of any abnormality, the technical team and sand preparation team shall be notified in time.
4. The continuous sand mixer shall be operated by a specially assigned person. Before startup, it shall be checked that the required sand amount, resin amount and curing dose shall be sufficient, and the air pressure shall be normal.
5. The operator shall check whether the continuous sand mixer operates normally.
① Turn on the power supply and use the manual button to return the resin and curing agent pipeline once. Purge the air in the pipe.
② During automatic feeding, the number of revolutions of resin pump and curing agent pump shall be adjusted according to the process requirements: generally, the tensile strength of resin sand for medium and small parts shall be controlled above 0.5MPa, and the tensile strength of resin sand for large castings shall be controlled above 0.7MPa. The manipulator is responsible for adjusting the dosage, and the molding sand tester is responsible for performance testing.
6. Check whether the pattern and core box are complete and intact, and whether the casting words are complete and clear.
7. The opening of the sand box shall be cleaned without adhesive, sand, iron sheet, etc.
4、 Molding and core making
1. Before sand filling, the bottom plate, formwork and core box shall be placed stably and leveled, the surface of the pattern and the inner cavity of the core box shall be wiped clean, and the release agent shall be applied as required.
2. When the shape of non formwork shape is heavy, iron wire or iron hook shall be used to fasten the shape on the box belt to avoid falling off when turning over the box.
3. During sand filling, the deep groove of the pattern or core box, under the boss and the parts with weak strength shall be compacted first. Iron nails or iron wires shall be embedded for reinforcement when necessary, but the nails and iron wires shall not expose the sand mold surface: during sand compaction, the pouring riser, cold iron and movable block shall not be displaced. Scrape the sand filling surface after sand filling.
4. When the iron core needs to be placed in the sand core and suspended sand, the sand consumption of the core iron shall be uniform and appropriate, generally not less than 20mm. In special cases, it shall be implemented according to the special process documents.
5. The sand core to be pierced with air holes shall be pierced with air holes as required within the available time. The complex sand core can be wound with nylon air eye rope on the core iron. The position of cold iron shall be correct, and the surface of cold iron shall be smooth and free of rust, water and oil.
6. On the premise of ensuring the thickness of the core, most of the core can be filled with waste sand blocks or other fillers to reduce the consumption of resin sand and improve air permeability.
7. The mold pulling and core pulling shall be completed within the demoulding time, and shall not be too early or too late.
8. The pattern and core box shall be loosened slightly and evenly when the core is pulled out from the formwork (non formwork modeling). During loosening, it is not allowed to directly knock the pattern and core box with iron, brick and other hard objects, but shall be padded with wood blocks or rubber, or knocked with a wooden hammer.
9. When the small core box is reversed, a backing plate shall be used. When the large core box is reversed, the core bone shall be fixed on the back of the core box with iron wire.
10. After the pattern and sand core are pulled out, the damaged and crisp parts of the mold and core can be repaired with newly mixed sand; If the block is broken and the broken part is intact, it can be bonded with bonding paste. The repaired and bonded part shall be of good quality, and the sand mold and sand core shall be scrapped.
11. After the sand mold and sand core are cleaned, the paint shall be brushed evenly and smoothly without accumulation and sagging. A certain layer thickness shall be ensured (0.2-0.5mm for iron castings and 1.0-2.5mm for steel castings). After the quick drying paint is brushed, it shall be ignited immediately.
12. For castings with traceability requirements, the team leader shall be responsible for replacing the casting date words, and the technical team leader of the packaging team shall be responsible for replacing the nodular iron test block words.
5、 Closed box
1. The lower profile shall be laid flat before closing the box, preferably on the loose sand ground with lion airway.
2. The sand mold and sand core shall be cleaned before core lowering, and the untested sand mold and sand core cannot be used.
3. When closing the box, if the sand core has moisture regain, it shall be baked on the surface with a blowtorch. If the moisture regain is serious, it shall be scrapped.
4. After the core is lowered, check whether its position is correct. If necessary, use the special lower core chuck for inspection. The shape and important parts shall be inspected before being packed.
5. After closing the box, install the fastening card, and then pull out the box pin. Cover the pouring riser with hard paper or iron sheet. When the pressure iron pressure box is used, the pressure iron shall be greater than 2 times of the box lifting force, and the pressure iron shall not cover the airway of the sand mold. After the box is closed, the clearly filled "box closing pouring identification card" shall be placed.
6. The core shall be poured within 24 hours after the box is closed, which shall not exceed 48 hours at most. The core exceeding the storage time shall be unpacked, dried and inspected again.
7. The production of key castings shall be organized according to special operation instructions, and the above contents can be used for reference.
6、 Production summary
1. For the production of key castings, the technical team is responsible for convening the production technology preparation meeting attended by technicians, team leaders and operators, and formulating operation instructions.
2. For castings produced in batches, the technical team is responsible for using statistical technology to analyze the causes of production defects and customize corrective measures. The team is responsible for implementation. The technical team shall track the improvement and prepare operation instructions.
3. The casting production operation instructions prepared by the technical team shall be stored in the workshop technical archives after verification.
The technician of workshop package team is responsible for the above work, and the technical team leader is responsible for inspection.
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