SU1484403A1 - Method of manufacturing thin-wall roll-formed sections - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular, to the technology for producing thin-walled bent profiles in rolls of a roll forming mill. The purpose of the invention is to improve the quality of the profiles by preventing the longitudinal bending of the ends of the profile and the helical twisting. In the manufacture of thin-walled profiles in each transition, one of the main axes of inertia of the section of the profile is aligned with the plane passing through the contact point of the circumferences of the main roll diameters of the bending mill perpendicular to the plane passing through these circles. The method allows to ensure the accuracy of the geometric dimensions of the profile along the entire length. 2 ill., 2 tab.

Description

The invention relates to the processing of metals by pressure, in particular to the production technology of thin-walled bent profiles in rolls of a roll forming mill.

The aim of the invention is to improve the quality of the profiles by preventing the longitudinal bends of the front and rear ends of the profile.

FIG. 1 shows a symmetrical corner profile, a cross section, and the position of the principal central axes of inertia; in fig. 2 - unequal-shelf channel, cross section and position of the main central axes of inertia.

In the manufacture of thin-walled bent profiles 1 and 2, one of the main axes of inertia of section 3

or 4 are aligned with the plane passing through the point of contact of the circumferences of the main diameters of the rolls of the roll forming mill perpendicular to the plane passing through the said circles to ensure equal axial deformations and stresses in the section section and uniform distribution of the profile inset into the upper and lower rolls relative to their main diameters

The profiling modes are determined as follows.

For symmetric profiles, the total displacement of the profile edge in the i-th junction A is determined by the formula

A 0,5A (1 - cos-c-),

$

00 4b

About 00

where A is the total horizontal

edge displacement of the bendable element in the last transition, mm;

N is the number of transitions necessary for bending a single element; i is the sequence number of the transition.

For certain total displacements A, calculate the hem angles a; on all transitions.

Draw a sketch of the projected transition.

Split the cross-section of the cap in the projected transition to rectangular elements of width b and b2 and thickness s.

Choose an arbitrary system of rectangular coordinates x, y so that the coordinate y is parallel to the axis of symmetry.

Coordinate mustache of center of gravity C of cross section (coordinate xc is known because the profile is symmetric) is determined by the formula

2; s; yc

CS Јb; S,

The main inertia axes V and U are drawn through the center of gravity C, and the coordinate V coincides with the axis of symmetry of the profile.

Through the center of gravity C, the horizontal axis AA is carried out, which coincides with one of the main axes of inertia U in such a way as to ensure the minimal insertion of the profile into the work rolls. The AA axis determines the position of the profile in the rolls of the roll forming mill relative to the main diameters of Vosn. o ° m

For asymmetrical profiles, angles

The hemmes I) - ,, X. by transitions are determined, depending on the type of profile, by known recommendations and by known nomograms.

Draw a sketch of the projected

transition.

Split the cross-section of the workpiece in the projected transition to rectangular elements of width b, b2, b3, ..., thickness s,

Choose an arbitrary system of rectangular coordinates x, y.

The coordinates xc and at the center of the body weight of the cross section C of the workpiece are determined by the formulas

 b; S; xc; b, s,

CSS

Lb-S tyc, Zb; S, through the center of the sheet C, the rectangular coordinates are carried, parallel to the coordinates xy.

Determine the moments of inertia for the coordinates X0y0 by the formulas

Y

+ B2- F,

gdz d is the distance from the x &coordinate; Y, Y, o + d .F,

where B is the distance from the y coordinate to the y coordinate;

 V +

where F is the profile section area; Y (T is the central moment of inertia of the cross section about the axis yn;

YXO is the central moment of inertia of the cross section relative to the xB axis;

Yu0y0 is the central moment of inertia of the cross section relative to the xy axis, 0.

Determine the position of the main central axes of inertia U and V relative to the coordinate system x0 and y0 according to the formula 7

35

tg2a

TY, e-YXe)

j 2

2Yaot0

V v

 Yx0

0

0 where a is the angle of inclination of the main axes of inertia V and U relative to the coordinate system x0 and EO.

Through the center of gravity C, a horizontal axis of the BB, which coincides with one of the main axes of inertia, is carried out in such a way as to ensure the minimal insertion of the profile into the work rolls.

The BB axis determines the position of the profile in the rolls of the roll forming mill relative to the guilty diameters of the upper and lower wapks and DOCH. c,.

For example, the profiling mode of a 30x30x2 symmetric angle made of steel 08 KP, determined by the proposed method, is given in Table 1.

Profiling mode of unequal 45x30x15x2 channel steel

Transitions

1 2 3 4 5 6 7 8 9

8 18 26 34 40 45 45 47 45

2 3 10 20 30 35 40 47 45

table 2

3.52

7.43

9.15

10.85

14.27

14.43

14.53

14.51

15.00

The angle of inclination of the main axes of the inertness a, hail

AND

6

15 22 30

40 45 45 47

45

four

/

four

/ g

Vs

B1

#L l

te. /

# ig.2

Claims (1)

A method of manufacturing thin-walled bent profiles, including multi-junction bending of profile elements in rolls, in which at each transition a profile is obtained with equal moments of bending resistance of the section parts relative to the vertical axis passing through the center of gravity of the profile section, characterized in that, in order to improve the quality of the profiles by preventing longitudinal bends of the front and rear ends of the profile, in each transition the profile is placed so that one of the main central axes of inertia is combined with the plane bore passing through the contact point of the circles of the main diameters of the upper and lower rolls perpendicular to the plane passing through the said circles.