TECHNICAL FIELD

The present invention relates to the field of near-net-shaping and additive manufacturing of special-shaped steel pipe for large-scale connecting pipes used in nuclear power, and in particular, to an inner cavity near-net-shaping device for micro cast-rolling additive manufacturing of large-scale special-shaped pipe.

BACKGROUND

Large-scale special-shaped connecting pipes for nuclear power are mainly used in nuclear power generators. They have special materials, irregular inner holes and irregular shapes and complex shapes, and because they need to withstand high temperature and high pressure steam under working conditions, they have strict requirements on microstructure and internal defects. Currently, they mainly rely on forging process to produce. The forging process has a long production process and a complex process, requiring large-scale forging equipment and flaw detection devices, so the production cost of large-scale connecting pipes remains high.

Large-scale steel pipes with irregular shapes are often used in industrial production. Due to their special shapes and large volume, compared to the common regular shape steel pipes in daily life that are manufactured by casting and rolling and other long process methods, they can be produced by welding when the shapes are regular and the wall thicknesses are small. With the development of science and technology, a more advanced near-net-shaping manufacturing method such as additive manufacturing has emerged, which can greatly shorten the manufacturing process and reduce intermediate links. At the same time, it can effectively control internal organization and defects, and can significantly reduce product production costs. For the manufacture of large irregular steel pipes, corresponding manufacturing equipment must be designed.

The irregular shape of the inner cavity of the special-shaped connecting pipe for nuclear power, and how to keep the position of the processed part fixed during the processing, make the processing by the conventional method technically limited, and an inner cavity forming device needs to be designed.

SUMMARY

In view of the problems existing in the prior art, the present invention provides an inner cavity near-net-shaping device for micro cast-rolling additive manufacturing of large-scale special-shaped pipe, which mainly solves the problem of maintaining the position of the workpiece fixed during processing, adapts to the manufacture of more large-scale irregular steel pipes, improves versatility, reduces production cycle, and improves efficiency.

The present invention provides an inner cavity near-net-shaping device for micro cast-rolling additive manufacturing of large-scale special-shaped pipe, and the device includes a main transmission assembly, an inner cavity near-net-shaping assembly and a main feed assembly. The main transmission assembly comprises a servo motor, a servo motor base, a main transmission coupling, a first main shaft bearing seat, a second main shaft bearing seat, a first main shaft lower slider, a second main shaft lower slider, a first bearing end cover, a second bearing end cover, a third bearing end cover, a fourth bearing end cover, a first main shaft bearing, a second main shaft bearing and a hexagon head bolt. The main feed assembly comprises a main guide, a ball screw, a stepping motor, a stepping motor seat, a coupling, a main feed ball screw nut, a first ball screw nut, a second ball screw nut, a ball screw bearing seat, a ball screw bearing, a first ball screw bearing end cover and a second ball screw bearing end cover. The inner cavity near-net-shaping assembly comprises an inner cavity mold, an expansion cylinder and an expansion push rod, the expansion cylinder is provided with a gap in a direction of a thin wall thickness thereof, an inner cavity surface of the expansion cylinder is evenly distributed along a circumferential direction thereof with the inner wedge-shaped slider, and the expansion push rod comprises a first shaft section, a second shaft section, an outer wedge-shaped slider and a third shaft section, an outer surface of the second shaft section of the expansion push rod is evenly distributed along a circumferential direction thereof with an outer wedge-shaped slider, a slope surface of the inner wedge-shaped slider is connected to a slope surface of the outer wedge-shaped slider, and the first shaft section of the expansion push rod passes through an inner diameter of the second bearing end cover, an inner diameter of the first main shaft bearing and an inner diameter of the first bearing end cover respectively and is connected to a second end of the main transmission coupling, and the third shaft section of the expansion push rod passes through an inner diameter of the third bearing end cover and an inner diameter of the fourth bearing end cover respectively and is connected to an inner diameter of the second main shaft bearing.

Compared with the prior art, the present invention has the advantages as follows.

First, by replacing the inner cavity mold of the inner cavity near-net-shaping assembly, near-net-shaping of the inner cavity of various types of connecting pipes for nuclear power can be achieved, and the expansion function can be realized through the movement of the feed structure. The process is relatively simple, and is easy to operate. At the same time, it reduces the labor intensity of workers, intermediate manufacturing links and the time to redesign new equipment, improves work efficiency, shortens the processing cycle, and can effectively control internal organization and defects, which has great practical application value.

Second, the structure is simple, easy to disassemble and assemble, can be used multiple times. Each part is replaceable, and has the characteristics of wide use, reduced production cost, stable performance, easy installation and implementation.

