Nuclear island evaporator sleeve part hole forming method

Abstract

The invention discloses a nuclear island evaporator sleeve part hole forming method. The nuclear island evaporator sleeve part hole forming method comprises the steps of (1), steel ingot heating; (2),forging stock blanking; (3), forging stock upsetting and pulling; (4), primary punching; (5), secondary punching, specifically, a demoulding expanding agent is filled into the inner cavity of a punching head, and the demoulding expanding agent makes contact with the high temperature forging part hole bottom to be expanded to push the punching head out of a hole; (6), three-time punching, specifically, the demoulding expanding agent is filled into the inner cavity of the punching head again, and the punching head is pushed out after expanding; (7), four-time punching, specifically, the demoulding expanding agent is further filled into the inner cavity of the punching head, and the punching head is pushed out after expanding; (8), hole trimming; (9), heat treating after forging. The demoulding expanding agent comprises the ingredients of, in percentage by mass, 8-12% of tung oil, 20-25% of saw powder, 10-15% of graphite, 3-5% of water and the balance blind coal, and the filling amount of the demoulding expanding agent at a time is 200-500g. By means of the nuclear island evaporator sleeve part hole forming method, longhole punching performed on nuclear forging parts is realized, andthe nuclear island evaporator sleeve part hole forming method has the advantages that the demoulding speed is fast, the tissue of the forging parts is uniform and dense, and the material utilizationrate is high.

Description

technical field [0001] The invention relates to the technical field of forging holes for large-scale structural parts used in nuclear power, and in particular to a deep-hole stamping method for forging parts such as an upper head, a lower head, a tube plate, a cylinder body, and a connecting pipe of a nuclear island evaporator. Background technique [0002] The nuclear power nuclear island steam generator is one of the three major equipments in the island. It is the boundary of the primary circuit and the secondary circuit of the pressurized water reactor nuclear power plant. It transfers the heat generated by the reactor to the secondary side of the steam generator. , After the secondary steam-water separator is dried, it drives the turbogenerator to generate electricity. Therefore, the connection between the nuclear power steam generator and the reactor pressure vessel not only directly affects the power and efficiency of the power plant, but also plays a role in blocking ...

AI Technical Summary

Problems solved by technology

However, during the stamping process of the deep hole of the kit forging, due to the large friction between the punch rod and the hole wall of the blank, coupled with the tightening force of the hole wall on the punch rod and the resistance at the end of the punch, the punch after punching It cannot be pulled out from the blank, so it is difficult to realize the deep hole processing through the stamping forming process for the deep hole of the steam generator kit forging. Hole cutting, but this processing method has many shortcomings: First, the material utilization rate is low, and the chips generated during the machining process of the hole become waste and are difficult to reuse, resulting in a great waste of high-quality alloy materials

Second, the cutting process cannot change the structure of the material around the hole wall, which is not conducive to enhancing the temperature and pressure resistance of the parts. Since nuclear power forgings are large thick cake solid forgings, it is difficult to heat through and compact. There are differences in the thermodynamic and dynamic conditions of the layer and the core. There are defects such as segregation, porosity, and shrinkage cavity inside the billet, and the deep hole is often located in the center of the billet where cracks and coarse grains are the most serious. It is difficult to guarantee the axis of the tube hole during cutting. To the consistency of mechanical properties

Third, the machining process is complicated and the production efficiency is low. Because the long diameter of the deep hole is relatively large, it needs to be drilled and then bored to the predetermined size during processing. Therefore, the workpiece needs to be transferred in multiple processes, the production cycle is long, and the efficiency Low