| 摘要 |
A method of producing profiled sections for the manufacture of vehicle door hinges, involving hot rolling of billets with rectangular cross-section in a series of passes, characterized in that a steel billet is heated to a temperature of 1,150 degrees C to 1,220 degrees C and is rolled in seven successive passes with cross-section reduction, where in the first pass both longer surfaces are deformed so that the outline of the cross-section is formed in the most part, symmetrically with respect to the axis, by two parallel straight lines, of which one within the edges passes through radially in the direction of increase in the thickness of the cross-section, while the other within the edges passes through at first radially in the direction of reduction in the thickness of the cross-section and then radially in the direction of increase in the thickness of the cross-section, whereas in the second pass the profiled section is rotated by an angle of 180 degrees and the outline of one surface is retained from the first pass by re-using the profile of the central cylinder used in the first pass, while the other surface within the edges of the profiled section is given a convex shape, with a simultaneous increase in the transition radii, where in the first pass an average reduction of 27 percent is used and in the second pass the average reduction is 35 percent, while the transverse dimension increases in these passes by 1.5 percent to 4 percent on average, after which in subsequent passes the thickness of the flat part of the profiled section is gradually reduced, while retaining the approximate proportions of reduction to increase in transverse dimension, as in previous [à]<IMAGE>
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