RU2038884C1 - Method of preparing strips for rolling different-thickness trough-like cross section shapes - Google Patents

Abstract

FIELD: rolling processes. SUBSTANCE: method comprises steps of providing an inlet portion at a front end of a strip by cross shaping of that portion according to a shaped grooved pass of rolling rolls. A length of the portion, had been shaped by such way, is determined by relation, formulated according to conditions of reliable biting of the shaped end portion of the strip by lateral walls of the grooved pass. Upon making shapes of hard-to-deform materials the inlet portion is being softened along a length of a part, had been shaped, and a part, respective to a zone out-of contact deformation at a process of preparing the strip for rolling. EFFECT: simplified preparation process. 1 cl, 3 dwg

Description

 The invention relates to the processing of metals by pressure and can be used at engineering and metalworking enterprises to prepare strips for rolling precise thin-walled trough-shaped profiles with different thicknesses of cross-sectional elements.

 A known method of manufacturing bent profiles from hardly deformed sheet alloys for two technological transitions in the cold state. To carry out the shaping of strip blanks at their inlet end, a tapering section is performed.

 However, this method is limited in its technological capabilities, i.e., it does not allow to obtain profiles with a variable thickness of cross-sectional elements during one technological transition from high-strength materials, for example, from titanium alloy VT 20.

 The technical problem solved by the invention is the expansion of the technological capabilities of the process of manufacturing profiles.

При этом для изготовления профилей из высокопрочных сплавов заходный участок заготовки создают с предварительным разупрочнением передней части полос на длине L_п l_о + l_в, где D_макс ^в максимальный диаметр охватывающего верхнего ролика;
D_{раб.макс} ^в максимальный рабочий диаметр охватывающего верхнего ролика;
H_л расстояние от оси охватывающего ролика до линии, проходящей через проекции на вертикальную плоскость точек пересечения окружностей, образованных максимальным рабочим диаметром охватывающего ролика и максимальным рабочим диаметром охватываемого ролика;
l_в длина зоны внеконтактной деформации в процессе подготовки полосы для прокатки.The problem is achieved in that in the method of preparing the strips for rolling shaped trough-shaped profiles, including creating a lead-in section on the strip, the lead-in section is formed in the transverse direction in accordance with the shaped gauge of the rolling rollers, and the length of this section is determined taking into account a reliable grip from the ratio
l _o ≥

Moreover, for the manufacture of profiles from high-strength alloys with lead-in portion of the blank creates a preliminary softening front of stripes on the length L _{f of the} l + l _a, where D _max ⁱⁿ the maximum diameter of the upper covering roller;
D _slave.max ^{in the} maximum working diameter of the covering upper roller;
H _{l is the} distance from the axis of the enclosing roller to the line passing through the projections onto the vertical plane of the intersection points of the circles formed by the maximum working diameter of the covering roller and the maximum working diameter of the covered roller;
l _{in the} length of the zone of non-contact deformation during the preparation of the strip for rolling.

 The essence of the invention lies in the fact that to expand the technological capabilities of the process of manufacturing profiles, in particular for the implementation of shaping in rollers in one technological transition from a strip blank, reliable capture of the strip by forming rollers is necessary. This requires a significant narrowing of the entry section of the workpiece, which leads to its large elongation. However, then a significant part of the metal (inlet section) goes to waste. In addition, in the manufacture of profiles from high-strength alloys, heating the main part of the workpiece and its elongated end of variable cross section over a long length by known methods of electric contact heating is a technically difficult task. It is impossible to direct the unstressed lead-in portion of the workpiece into the rollers, as this can lead to its destruction or damage to the rollers themselves. Therefore, the lead-in section is formed in the transverse direction in accordance with the shaped gauge of the rolling rollers, and when manufacturing profiles from high-strength alloys, the front end of the workpiece is preheated to the temperature of plastic deformation. Also, the electrical contact heating of the workpiece with a lead-in section is greatly simplified, since the tapering part of a variable section is excluded.

 Such a technical solution allows us to solve the problem, provided that high-quality profiles are obtained.

 Figure 1 shows the original strip blank with a molded lead-in section; in FIG. 2 diagram for determining the length of the lead-in section; figure 3 forming rollers to obtain trough-like profiles.

 Profile rolling can be carried out from strips cut from a sheet or tape supplied by metallurgical enterprises. On the front parts of the strips to ensure capture by rolling rollers, a lead-in section is formed in a stamp (Fig. 1) for hard-to-deform alloys, having previously weakened the lead-in section to the temperature of plastic deformation, for example, by electric contact heating.

(1) где D_макс ^в, D_{раб.макс} ^в максимальный и минимальный рабочие диаметры верхнего охватывающего ролика (фиг.1).The length l _{o the} lead-in section is determined from the geometric relationships of the forming rollers and the conditions for a free approach and the capture of the shaped lead-in section by the inclined elements of the forming rollers from the following ratio:
l _o ≥ (ab)

(1) where D _max ⁱⁿ , D _slave.max ^{in the} maximum and minimum working diameters of the upper female roller ( _figure 1).

The segment N _l is the distance from the axis of the enclosing roller to the projection on the vertical axis of point "b", which is selected from the condition of capture of the lead-in section by inclined elements of the forming rollers experimentally. It coincides with the projection onto the vertical plane of the intersection point of the circles formed by the maximum working diameter of the female roller and the maximum working diameter of the male roller (figure 2).

The error of the values obtained by the formula (1) does not exceed 5%
For the manufacture of profiles from high-strength alloys, for example, from VT20 titanium alloy, the length of the softened part is determined by the formula L _p ≥ l _o + l _in , (2) where l _{is the} length of the zone of non-contact deformation.

 An example of calculating the length of the entry area and the length of the softened zone.

Initial data: D _slave.max ⁱⁿ 355 mm; D _max ^at 386 mm; D 350 mm; D _slave.max ⁿ 362: 8 mm; γ _p 83 ^o ; h _o 2 mm; in _d 12 mm.

Bringing the calculation according to the formulas [1 and 2] get
l _about 44.3 mm; L _p ≥ 128.5 mm.

 The implementation of this method can be carried out using a heating installation and a stamp, as well as a modernized rolling mill DUO-350 for the process of strip billets by rolling with electric contact heating. The proposed method was tested on this equipment.

The parameters of the initial billet and the molded lead-in section are as follows: thickness of the initial billet 2.0 mm, width 56 mm, length 2000 mm, material VT20 titanium alloy (δ -10% σ _at 930-1080 MPa); the length of the shaped-deformed lead-in section is 45 mm, obtained in a stamp with preliminary softening, electrical contact heating of a section 130 mm long. After fabrication Pan sections (legs) has the following dimensions: thickness at the flange profile base (legs) of 1.5 mm, thickness 1.3 mm inclined walls, the thickness profile of the shelf at the top of 1.7 mm, a wall angle of inclination ^of the shelves 83, the outer radius at the top of the profile is 3.5 mm, the inner 2 mm, the outer radius at the base of the profile is 0.7 mm, the inner 2 mm, the width of the legs is 13 mm, the width of the top of the profile is 12.1 mm, the height of the profile is 12 mm and its width is 41 mm .

 Using the proposed method allows to increase labor productivity by reducing the number of technological transitions, eliminating the time required for transshipment of the mill, reducing the number of technological equipment for manufacturing profiles, saving material profiles, since the inlet section does not go into waste, reduce the amount of finishing work by eliminating intermediate workpieces transitions.

Claims (2)

1. METHOD FOR PREPARING STRIPS FOR ROLLING DIFFERENT THREADS IN SECTION OF SHAPE PROFILES, including creating a run-in section on the strip, characterized in that the run-in strip section is formed in accordance with the shaped gauge of the rolling rollers in the transverse direction, and the length l _about this section is selected taking into account the reliable grip from the relation

where D $\genfrac{}{}{0ex}{}{\text{in}}{\text{m}}$ _ax maximum diameter of the female upper roller;
D $\genfrac{}{}{0ex}{}{\text{in}}{\text{R}}$ _ab.max maximum working diameter of the covering upper roller;
H _{l is the} distance from the axis of the enclosing roller to the line passing through the projections onto the vertical plane of the points of intersection of the circles formed by the maximum working diameter of the covering roller and the maximum working diameter of the covered roller. 2. The method according to claim 1, characterized in that in the manufacture of profiles of high-strength alloys, the lead-in section of the workpiece is created with preliminary softening of the front of the strip along the length
L _n > l _o + l _in ,
where l _{is the} length of the zone of non-contact deformation during the preparation of the strip for rolling.

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