Method of near-net-shape forged molding of coupler knuckle of railway vehicle

Abstract

The present invention provides a method of near-net-shape forged molding of the coupler knuckle of the railway vehicle. The present invention solves the problems that the manufacturing the forged coupler knuckle is difficult, and the process is complex, etc. The method of the present invention includes the following steps: material preparation, heating, blank prefabrication, pre-forging, closed-die forging, quenched-tempered heat treatment using waste heat, finish machining, flaw detection, etc. With the closed-die forging technology, the near-net-shape molding of the coupler knuckle can be achieved. The energy and the material are saved. The contour shape and the size do not need to be machined. The use ratio of the material can reach more than 92%. Moreover, during the entire molding, the workpiece is in the three-dimensionally stressed state all the time. The product has a dense texture, a high toughness, a good fatigue resistance, and a long lifetime.

1 . A method of near-net-shape forged molding of a coupler knuckle of a railway vehicle, comprising the following steps:
 Step (a) material preparation;   Step (b) heating: heating a rough at 1150° C.±20° C.;   Step (c) blank prefabrication: positioning the heated rough on an 800-ton multi-directional forging apparatus for multi-directional forging to prefabricate the blank;   Step (d) blank pre-forging: closed-die forging the prefabricated blank in a pre-forging die on a 2000-ton multi-directional forging apparatus;   Step (e) near-net-shape forged molding: closed-die forging the pre-forged blank positioned in a multi-directional forging die on a 6000-ton multi-directional forging apparatus, so as to achieve near-net-shape molding;   Step (f) thermal treatment: performing a quenched-tempered heat treatment on the forged blank using waste heat;   Step (g) finish machining: processing a pinhole of the coupler knuckle using a numerical control machining machine; and   Step (h) flaw detection: performing a magnetic powder flaw detection on the finished product.   
     
     
         2 . The method of near-net-shape forged molding of the coupler knuckle of the railway vehicle according to  claim 1 , wherein in the Step (c)
 performing the blank prefabrication on the multi-directional forging apparatus;   moving a die in a vertical direction and a die in a horizontal direction in an interleaved manner;   manufacturing the heated rough into a prefabricated blank with a certain height and a certain thickness while removing an oxide skin on a surface of the rough.   
     
     
         3 . The method of near-net-shape forged molding of the coupler knuckle of the railway vehicle according to  claim 1 , wherein in the Step (d)
 positioning the prefabricated blank in the pre-forging die of the multi-directional forging apparatus;   dividing the pre-forging die into four portions including an upper portion, a lower portion, a left portion, and a right portion;   driving the upper portion and the lower portion of the die by a vertical oil cylinder of the multi-directional forging apparatus;   driving the left portion and the right portion of the die by a horizontal oil cylinder of the multi-directional forging apparatus;   controlling a movement and a moving distance of each portion of the die by a program;   after each portion of the die is assembled, stopping moving of each portion of the die; and   pre-forging the prefabricated blank into a certain shape and a certain size.   
     
     
         4 . The method of near-net-shape forged molding of the coupler knuckle of the railway vehicle according to  claim 1 , wherein in the Step (e)
 achieving the near-net-shape molding of the coupler knuckle by the multi-directional forging apparatus and the multi-directional forging die;   splitting the multi-directional forging die horizontally and vertically in a mixing manner;   after the pre-forged blank is positioned in the multi-directional forging die, at first, driving the left portion and the right portion of the die in a horizontal direction to start to move by the horizontal oil cylinder of the multi-directional forging apparatus;   extruding the pre-forged blank;   after the left portion and the right portion of the die are assembled, locking the die;   driving the upper portion of the die in the vertical direction to move downward rapidly by a main oil cylinder;   when the upper portion of the die is about to contact the blank, slowing down the main oil cylinder, and starting the closed-die forging, wherein a moving speed of the upper portion of the die is adjustable in a stepless manner and is controlled by the program;   during the entire forging, keeping a rate of deformation of the workpiece substantially the same all the way;   when a pressure of the main oil cylinder reaches a predetermined value, finishing the entire forging process;   returning the upper portion of the die rapidly while moving an upper ejection oil cylinder such that the workpiece is maintained without moving upward together with the upper portion of the die;   splitting and returning the left portion and the right portion of the die;   next, driving the lower portion of the die by a lower ejection oil cylinder to move upward to push out the workpiece; and   completing the near-net-shape forged molding.   
     
     
         5 . The method of near-net-shape forged molding of the coupler knuckle of the railway vehicle according to  claim 1 , wherein in the Step (e)
 providing the horizontal die of the multi-directional forging die with a built-in hydraulic cylinder and movable module;   during the closed-die forging, when the upper portion of the die moves downward to reach a certain position, controlling the built-in hydraulic cylinder by the program to start automatically to push the movable module, so as to achieve a partial molding of a pocket portion of the coupler knuckle workpiece;   while the upper portion of the die is returning rapidly, starting the built-in hydraulic cylinder to return, so as to drive the movable module to return; and   after the movable module returns to an original position, splitting and returning the left portion and the right portion of the die.   
     
     
         6 . The method of near-net-shape forged molding of the coupler knuckle of the railway vehicle according to  claim 1 , wherein in the Step (f)
 after the workpiece is molded, performing a quenched-tempered heat treatment using the waste heat;   after the near-net-shape forged molding of the workpiece is completed, measuring a temperature using an automatic temperature measuring system;   next, entering the workpiece into a soaking pit;   based on the comparison of the temperature measured by the automatic temperature measuring system and the quenching temperature, performing a heating-up treatment or a cooling-down treatment by the soaking pit on the workpiece automatically; and   monitoring and automatically controlling a time for the workpiece to stay in the soaking pit in real time by an accompanying automatic temperature measuring system.