Scope of use of construction machinery castings


Release time:

2022-06-17

Engineering machinery casting product is a large casting, which needs heat treatment to improve the self-use performance and the internal quality of cast iron castings. Metal heat treatment is an important process in mechanical manufacturing. Heat treatment generally does not change the shape and overall chemical composition of the workpiece, but changes the microstructure of the workpiece or changes the chemical composition of the workpiece surface, thus giving the workpiece performance. Characterized by the internal quality of the workpiece.

Engineering machinery casting product is a large casting, which needs heat treatment to improve the self-use performance and the internal quality of cast iron castings. Metal heat treatment is an important process in mechanical manufacturing. Heat treatment generally does not change the shape and overall chemical composition of the workpiece, but changes the microstructure of the workpiece or changes the chemical composition of the workpiece surface, thus giving the workpiece performance. Characterized by the internal quality of the workpiece.

工程机械铸件

In order to provide the required mechanical, physical and chemical properties of metal workpieces, the heat treatment process is often the same in addition to the reasonable selection of materials and various molding processes. Steel is a widely used material in the machinery industry. The microstructure of steel is complex and can be controlled by heat treatment. Therefore, the heat treatment of steel is the main content of metal heat treatment. In addition, aluminum, copper, magnesium, titanium and their alloys can be heat treated to change the mechanical, physical and chemical properties, to obtain a variety of performance.

The overall heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at an appropriate rate to change the overall mechanical properties. The overall heat treatment of steel generally has four basic processes, such as annealing and purification.

The material of the construction machinery casting is fine gray cast iron, which is equipped with 45% steel when melted, which improves the rigidity of the mechanical casting. There are also customer requirements for the production of ductile iron. The rigidity of ductile iron is better than that of gray cast iron, but the damping effect is very different than that of gray cast iron, and the casting cost is much higher than that of gray cast iron. Therefore, ductile iron is not suitable for the main components of the machine tool, and is more suitable for machine tool table castings.

Benefits of using gray cast iron as construction machinery castings:

1. Gray iron casting machine casting cost is low, gray cast iron casting performance is good, easy to cast a variety of complex structure of the body.

2. Cast iron material has good shock absorption performance, which helps to prevent vibration and reduce noise during machine operation.

3. Compared with steel, the tensile strength of cast iron is lower, but the compressive strength is close to that of steel. Most machine tool beds do not require high tensile strength and can meet performance requirements.

4. The mechanical bed castings cast with gray iron material have good lubrication performance. Because the micropores of the atomic structure of gray iron can hold more lubricating oil, and the carbon contained in it has a self-lubricating effect.

5. Cast iron is easier to rust and corrode than steel, so it is easy to maintain the accuracy of the machine tool guide. The dimensional stability of machine tool castings is good, and the machine tool body cannot be deformed, which helps to maintain the accuracy of machine tool castings for a long time.

Inspection rules for construction machinery castings.

1. If the order contract requires magnetic particle inspection, penetration inspection, ultrasonic inspection, radiographic inspection, respectively, in accordance with GB/T 9444, GB/T 9443, GB/T 7233, GB/T 5677 or contract requirements for inspection.

2. The casting producer shall provide the chemical composition and mechanical performance test report to the demand side at the same time, which is indispensable, and attach the certificate of conformity of the casting to this standard.

3. In order to ensure that the casting conforms to the provisions of this standard or the contract, the casting producer shall provide the necessary convenience to the demander's inspector, but the inspection of the demander shall not affect the normal production of the casting producer.

4. If the demand side finds that the casting has harmful defects during the acceptance, if it thinks that it needs to be returned, it shall notify the casting producer within 30 days of the defect and negotiate a settlement.

5. The demand side objects to the casting material. The sample of the material shall be kept for 30 days from the date of sending the test report, during which time the casting producer may request a review.

6. When the demander makes a rejection decision based on the experimental report, it shall notify the casting producer within 30 days of receiving the report.

7. Each melting furnace of steel shall be subjected to a tensile test, and its mechanical properties shall conform to the provisions of Table 3. If not suitable, that casting and testing.

The block can be re-heat treated and repeatedly tested, but the number of times of unnecessary re-heat treatment cannot exceed two times (except tempering).

8. Test specimens shall be cast by casting and other furnaces and poured in accordance with GB/T 11352.

9. The test block should be heat treated in the production furnace according to the furnace such as the casting or the same process.

10. If necessary, samples may be cut from the casting after heat treatment according to the casting producer.

11. The shape and size of the sample shall be in accordance with GB/T 6397, and the test method shall be in accordance with GB/T 228.

12. If processing finds machining defects or casting defects, a replacement sample rework test is required.

13. Castings need to be tested in accordance with the provisions of GB/T13927. The shell test can be carried out before delivery by the casting producer or after processing by the demander, but the casting producer needs to be responsible for the quality of the shell test castings.