Die forging process and special die for final stage blade of large half-RPM (Revolution per Minute) nuclear turbine

Abstract

The invention provides a die forging process for a final stage blade of a large half-RPM (Revolution per Minute) nuclear turbine. The die forging of only single forging die is required to ensure the die forging forming of a blade forge piece, so that the manufacturing cost of the blade is reduced, the die forging cycle is shortened, and the processing efficiency is improved; moreover, the correction times inside the die of the blade forge piece is effectively reduced, and the production capacity of forging is increased. The invention has the technical scheme comprising the following steps of: upsetting a bar by using an oil press, stretching the bar in radial direction to prepare a blank, and forging the stretched blank in a forging die for forming; then, thermally cutting off the flashing fins for the die forging, and thermally correcting for the die forging; and finally, thermally treating. The process is characterized in that the radial stretching for preparing the blank adopts an electro-hydraulic hammer to carry out free forging and stretching to prepare the blank, and the blank is optimized into the structure with most circular cross sections and partial flat square cross sections. The invention also provides a special die which comprises an upper die and a lower die, wherein the four corner endss of the upper die are provided with guide pillars, and the lower die is correspondingly provided with guide sleeves. The special die is characterized in that the outer sides of the die cavities of the upper die and the lower die are side upright wall structures which are mutually overlapped, and the guide pillars and the guide sleeves are respectively arranged on the side upright wall structures of the upper die and the lower die.

Description

technical field [0001] The invention relates to the technical field of thermal processing, in particular to a die forging process and a special die for the last-stage long blades of a large half-speed nuclear power steam turbine. Background technique [0002] At present, the foreign large-scale half-speed nuclear power steam turbine last-stage long blade die forging process is to use a hydraulic press or a flat forging machine to head the bar, and then radially forge the forging machine to make a billet, then pre-forge and final forge to shape, and use the mold after the final heat treatment. Inner room temperature and pressure maintenance correction. The disadvantage is that the cross-sectional shape of the blank after being drawn by the radial forging machine is circular. Due to the influence of the cross-sectional shape of the blade, its forging must go through pre-forging and final forging, which requires the manufacture of pre-forging dies and final forging dies. Two s...

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Problems solved by technology

The disadvantage is that the cross-sectional shape of the blank after being drawn by the radial forging machine is circular. Due to the influence of the cross-sectional shape of the blade, its forging must go through pre-forging and final forging, which requires the manufacture of pre-forging dies and final forging dies. Two sets of forging dies, and general blade production dies have the characteristics of small batches and multiple varieties, and the mold cost accounts for a relatively high proportion of the total manufacturing cost, so the mold cost is high, and the manufacturing cost of the blade is high; and because the blank cross section is relatively single The shape of the wide-cho

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