SU1558530A1 - Method of bending profiles of angular section - Google Patents

Abstract

The invention relates to the processing of metals by pressure and can be used in aircraft manufacturing, the shipbuilding industry and other areas of mechanical engineering. The purpose of the invention is to improve the quality when bending corner profiles with a shelf outwards. When bending the profiles, one end of the workpiece 1 is fixed with the help of a clamping device 2 on the bending mandrel 3, and the other end in the clamping cartridge 4 of the stretching hydraulic cylinder. After preliminary axial stretching, profile 1 is bent-wrapped with bending mandrel 3 stretched. In the flexible zone, the thickness of the flange lying in the plane of bending is compressed using a pair of rollers 5 and the wall is perpendicular to the plane of bending. using the sizing roller 6 whose axis is inclined to the plane of bending at a predetermined angle α, which is calculated by the formula TGΑ = (ε -ε _{n c)} / a, where c - wall thickness

в - wall height

ε _p - the relative elongation of the outer fibers of the shelf

ε _c is the relative elongation of the fibers of the end portion of the wall after bending with axial stretching. The quality of the resulting products is improved by reducing the twist. 7 il.

Description

JV JV 00 JV

with

fae. 7

The invention relates to the processing of metals by pressure, in particular, to methods for bending profiles on a mandrel.

The purpose of the invention is to improve the quality of profiles when bending with a shelf to the outside.

FIG. 1 shows the arrangement of the outer fibers of the shelf, end and root

parts of the wall when bending corner profiles shelf outside; in fig. 2 is a section A-A in FIG. one; in fig. 3 and 4 - distribution of deformations and stresses in the tangential direction, respectively, along the height of the wall; in fig. 5 - additional elongation of the fibers of the wall due to its uneven compression; in fig. 6 — distribution of the resulting deformations and stresses in the tangential direction; : ia FIG. 7 - process diagram

When bending profiles of angular section with axial stretching of the shelf to the outside, according to a known method, its width across the width in the bending zone is variable in width. This leads to a greater elongation of the fibers of the shelf relative to the fibers of the wall, which makes it possible to compensate for the springing, but due to the uneven distribution of deformations in the tangential direction along the height of the wall (the fibers that are closest to the shelf, Fig. 3), the tensile stresses are redistributed in the tangential direction (Fig. 4), since the more elongated as a result of the compression of the flange of the fiber perceives a smaller part of the axial tension force. The stress diagram is unbalanced with respect to the center of gravity of the cross section, which results in a twist after the load is removed. With uniform compression along the wall height, perpendicular to the plane of the bend, uniform elongation of its fibers occurs, i.e., the stress pattern remains unbalanced with respect to the center of the cross-section of the cross section.

If we perform a non-uniform height reduction of the wall, perpendicular to the plane of the bend, with a maximum value at the edge equal to е „-еc (where гп is the relative elongation of the outer fibers of the shelf, 8С is the relative elongation of the end portion of the wall after bending with axial stretching) linearly down to zero at the root, this leads to a similar additional elongation of its fibers, since the broadening is almost absent and the problem can be considered as flat. Since the elongation of the fibers over the entire height of the wall is equal to e, then the stresses are evenly distributed, i.e. there will not be a moment of internal forces relative to the center of gravity and, therefore, no twisting after removing the load.

0 5 0

Q 5

five

The method was tested on an experimental setup, made according to the scheme of a profile-bending machine, equipped with a finishing device in the form of a rotary beam with a pressure cylinder and a calibrating roller, as well as a pair of rollers designed to be cut through the thickness of the shelf lying in the plane of the bend.

In the diagram (Fig. 7) of the technological process under consideration, one end of the blank 1 is fixed with the help of a clamping device 2 on the bending mandrel 3, and the other end in the clamping cartridge 4 of the stretching hydraulic cylinder. After preliminary axial stretching, a bend is wrapped around the profile with stretching along a bending mandrel 3. In the bending zone, the thickness of the flange lying in the plane of bending is compressed using a pair of rollers 5, and the wall is perpendicular to the plane of bending. using a calibration roller 6, the axis of which is inclined to the plane of bending at a given angle a, which can be calculated by the formula

tga (e.n-Ec) c / b,

where c is the wall thickness;

b - wall height.

Corner section profiles 15X15X XI, 5 mm from D16T were used as initial blanks. When bending with a shelf outward on a radius of 300 mm with an axial tensile force of 4 kN, a clamping force of 1.5 kN and a tilt angle of the axis of rotation of the calibrating roller to the bend plane, 3 °, with a maximum reduction in thickness of 3.5%, zero springback and twist values after the load is removed. When bending without rolling the wall, the twist amount is 2.5-3 °.

Experimental studies show that using the proposed method can significantly improve the quality of the parts produced by reducing the twist.

Claims (1)

Invention Formula The method of bending angular section profiles consists in bending the workpiece along the mandrel with application of axial tension to the workpiece and uneven radial reduction in thickness in the zone of wall bending, perpendicular to the plane of bending, with a maximum value of en-ec, decreasing to zero, where en is relative elongation of stick fibers, ec - relative elongation of fibers at the wall edge, characterized in that, in order to improve quality when bending profiles with a shelf outside, maximum compression is performed at the wall edge with decreasing to zero along the line this law. -I 1 Fi.T  ////////// Л Aa External KorneVa beams shelf part with tenck /, but Wall, Late & a part of the wall. FIG. 2 m FagL & tf in.