Integral die-forging method for frogs

Abstract

The invention discloses an integral die-forging method for frogs. The integral die-forging method comprises the steps of cogging, pre-forging and finish-forging, wherein during the cogging, original blanks heated to reach an initial forging temperature are pre-allocated in the axial direction through cross wedge rolling to obtain blanks; during the pre-forging, the blanks heated to reach the initial forging temperature are prefabricated through die-forging to obtain prefabricated blanks; and during the finish-forging, the prefabricated blanks heated to reach the initial forging temperature areforged through the die-forging to obtain the frogs. According to the method disclosed by the invention, formation is realized in the manner of cross wedge rolling cogging, die-forging pre-forging anddie-forging finish-forging, and after the cross wedge rolling cogging and the die-forging pre-forging, the form of the mass distribution of the prefabricated blanks is gradually converted to the formsimilar to the finish-forged pieces, of a plurality of the prefabricated blanks at the two ends and a few of the prefabricated blanks at the middle in the axial direction, and a plurality of the prefabricated blanks at the two sides and a few of the prefabricated blanks at the middle in the section direction, from the uniform-section form of the original round-rod-shaped blanks; the tendency of slip of the blanks due to instability during the pre-forging is reduced through the matching of the columnar characteristic of the blanks and the guide characteristic of the pre-forged die cavities; and the integral die-forging method is high in axial machining accuracy and material utilization rate, stable in process, and capable of realizing integral die-forging for the frogs under a low tonnage.

Description

technical field [0001] The invention relates to the technical field of forging, in particular to an integral die forging method for a frog. Background technique [0002] Long-shaft forgings with variable cross-section usually have the characteristics of large aspect ratio, complex shape in the middle and both ends. In practical applications, long-shaft forgings with variable cross-section usually need to bear alternating loads such as compression, tension, and bending. The quality puts forward higher requirements. In particular, super-long variable-section long-shaft forgings such as frog parts used on railways can reach more than 6 meters in length, and the cross-sectional shape along the axial direction changes complicatedly. At present, casting processes are generally used in mass production. [0003] However, with the continuous improvement of national requirements for the quality of heavy-duty railway lines, the performance of cast frogs can no longer fully meet the re...

AI Technical Summary

Problems solved by technology

[0006] If the free forging + machining process line is used, at least ten sets of lower anvils are required, which greatly prolongs the processing time and increases the number of heating times. At the same time, because precise forming cannot be achieved, additional dressing and additional processing allowance are required. The utilization rate is lower than 50%, and the blanking is at least 3 tons; and a large amount of dressing at the center of the fork will eventually be removed by subsequent machining, and subsequent machining will cut off the metal streamline formed by free forging, thus reducing the overall performance of the forging , and this part bears the severe impact of the wheel, which has high performance requirements, and the excessive cutting amount of machining may make the final frog forging not meet the requirements; in addition, the frog is more sensitive to the axial precision, and the axial precision in the free forging process It is difficult to control the amount of elongation in the direction, and the process stability is not high, which will eventually lead to a high scrap rate

[0007] If this type of frog is formed by die forging, the following problems will be introduced: the final forming tonnage is huge, and the mold clamping force is about 100,000 tons. The height of the inner filling is very large, and it is difficult to fill the shape at the root of the fork heel of the wing rail (that is, both ends of the forging), the winglet on the outer edge of the wing rail, and the ear plate rib. It is very sensitive, and the tonnage of subsequent die forging steps will increase significantly due to precision reasons

like image 3 and Figure 4 As shown, the section characteristics of this type of frog are mainly "U"-shaped and "П"-shaped surrounding sections, the filling height is high and the quality is mainly distributed on both sides along the section direction, which makes the blank width much smaller than the cavity width , plus its own length of 6 meters, it is very difficult to position the billet in the die cavity. The middle section of the billet is in a semi-suspended state during most of the stroke during the die forging process. The distribution will be affected, and in severe cases, the side thrust generated by the huge forging tonnage may even break the mold

In the die forging process, there is currently no positioning method for this type of forging blank, and it is difficult to achieve it under large-tonnage die forging by using double-action presses and other methods

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