RU2317166C1 - Section bending mill stand - Google Patents

Abstract

FIELD: plastic working of metals, possibly production of bent sections.

SUBSTANCE: stand includes mounted in chocks upper and lower calibrated rolls. Said chocks are arranged in housings having horizontal traverse bars, four guiding struts with diameter d and compression springs. Guiding struts pass through vertical openings of chocks. Compression springs are arranged in struts between upper chocks and horizontal traverse bars of housing. Guiding struts are provided with barrel like portion arranged symmetrically relative to horizontal axis of upper roll and having circular generatrix. Radius R of said generatrix is determined by expression R = 0.5(L + D) where L -distance between centers of chock cross sections along horizontal line. Maximum diameter D of barrel like portion of struts is determined by expression

Length of barrel like portion is equal to 1.2 d.

EFFECT: improved quality of bent sections.

2 dwg, 1 ex

Description

The invention relates to equipment for metal forming and can be used in mills for the production of high-quality bent profiles.

Such profiles of the most diverse cross sections (corner, channel, trough, C-shaped, etc.) are made on specialized roll forming mills containing forming stands. The cages consist of two beds, in which the upper and lower calibrated rolls are installed on pillows-supports, the upper of which is made with the possibility of vertical movement by a predetermined amount. The design of the molding stands of roll forming mills is described, for example, in the book by Y. S. Finkelshtein “Guide to rolling and pipe production”, M., “Metallurgy”, 1975, p. 247, Fig. 2.

The bed of each stand consists of two vertical posts connected from above by traverses on which pressure screws with a drive are installed to move the supports of the upper roll vertically.

Known working stand roll forming mill with two drive shafts on which the forming elements are mounted, and each pair of mating elements is equipped with an individual drive of their axial movement (see AS USSR No. 1022389 class. B21D 5/06, publ. In BI No. 17 , 1984). The disadvantage of this stand is the ability to roll out thickened sections along the length of the strip blank, for example, welds, which affects the quality of bent profiles.

The closest analogue to the claimed object is a stand roll forming mill according to US Pat. USA No. 3785191 class B21D 5/08, publ. 01/15/74.

This cage contains upper and lower calibrated rolls installed in pillows-supports located in the frames, and four cylindrical guide racks passing into the vertical holes of the pillows, and are characterized in that compression springs are installed on the racks between the upper pillows and the horizontal traverses of the frames, which allows the upper roll to rise up a certain distance when passing through the stand of a thickened portion of a strip blank formed in the stand.

A disadvantage of the known stand is the possibility of obtaining defective profiles if the workpiece has a wedge-shaped cross section.

Indeed, since the workpiece for forming high-quality profiles is obtained by longitudinal dissolution (cutting) of a relatively wide strip steel (with a width of 1.0 ... 2.5 m), the cross section of which has a lenticular shape (see, for example, book C. P. Efimenko and V. P. Sledneva “Roller of sheet rolling mills”, M., “Metallurgy”, 1980, p. 49 and fig. 42, p. 52 and fig. 45), then the narrow strips obtained from the edge (side ) sections of the original wide strip, have a wedge-shaped cross section. Given the value of the total (plus and minus) tolerance on the thickness of a wide strip of rolled products, with a longitudinal dissolution of which a narrower workpiece is obtained, it can be argued that for strips with a thickness of, for example, 8 mm (gauge roll forming mill 2 ÷ 8 × 100 ÷ 600), the thickness difference the edges of the billet for profiling reaches 0.9 ... 1.1 mm.

In this case, the thicker lateral edge of the moldable strip inevitably raises the upper roll (both of its pillows) by the indicated value. This is due to the fact that the difference in the diameters of the holes in the pillows and guides is very small (0.04 ... 0.06 mm) and the skew of the roll in the vertical plane practically does not occur. As a result of this, the bending radius “is not fulfilled” on the thinner edge of the formed strip in all mill stands (its value becomes larger than the permissible one), and the width of the bending side profile element (for example, the channel shelf) can go beyond the tolerance.

The technical task of the present invention is to improve the quality of mainly varietal bent profiles by improving their geometry.

- максимальный диаметр бочкообразного участка стоек, а длина указанного участка равна 1,2d.To solve this problem, in a stand of a roll-forming mill containing upper and lower calibrated rolls installed in pillows-supports placed in the frames, four cylindrical guide racks of diameter d passing into the vertical holes of the pillows and with compression springs on the racks located between the upper pillows and horizontal traverses of the bed, sections of the guide racks symmetrical with respect to the horizontal axis of the upper roll are barrel-shaped with a circular generatrix of a surface whose radius R = 0.5 (L + D), where L is the horizontal distance between the centers of the cross sections of the pillows,

- the maximum diameter of the barrel-shaped portion of the uprights, and the length of the specified portion is 1.2d.

The above mathematical relations are obtained from the condition that half of the difference in the values of Dd is the height of the segment in the transverse vertical section of the barrel-shaped section of the rack, having a length equal to 1.2d, and the radius of the circle, of which the segment is a part, is R. The validity of these relations is confirmed by experiments (see .below).

The design of the proposed stand is shown schematically in FIG. 1 (its upper part with pillows-supports of the upper roll is given), and in FIG. 2 - a barrel-shaped portion of the rack.

Pillows 2 are installed in the beds of the stand 1, in each of which two holes 3 are made for cylindrical guide racks 4 of diameter d (see FIG. 1). Between the pillows 2 and the horizontal traverse 5 of the stand on the uprights 4 are placed compression springs 6. The horizontal distance between the centers of the cross sections of the pillows is L.

причем разность диаметров отверстий в подушках и D должна обеспечить ходовую посадку стоек в отверстиях. Радиус R исходит из т.О, расположенной на середине расстояния между подушками (т.е. на оси yy и на горизонтальной оси верхнего вала 9).The barrel-shaped portion 7 of the strut 4 (see FIG. 2) has a length l and a maximum diameter D in the middle of this length. The radius of the circular generatrix 8 of section 7 is R = 0.5 (L + D), the length of this section is l = 1.2d, and the value

moreover, the difference between the diameters of the holes in the pillows and D should provide a running landing racks in the holes. The radius R proceeds from T.O. located in the middle of the distance between the pillows (i.e., on the yy axis and on the horizontal axis of the upper shaft 9).

The essence of the claimed technical solution lies in the possibility of creating a skew of the upper roll when passing through the caliber of the cage of the wedge-shaped strip (the roll, as it were, rotates around the vertical axis in a vertical plane), which ensures that its forming curves are in contact with the formed strip on both sides of the vertical yy. As a result of this, the radii of the bending points of the moldable section are obtained of the required size.

The device operates as follows.

When the wedge-shaped portion of the strip billet enters the caliber under the action of metal pressure on the roll from a thicker edge of the strip, the roll rotates around t.O., one of the pillows moves upward, compressing the spring, and the other pillow moves downward, "leaving" from the end of its spring (springs are freely placed on racks). This creates a wedge-shaped gap between the rolls corresponding to the actual cross section of the strip.

Moving the pillows up and down is accompanied by turning them in a vertical plane, and the surface of the holes in the pillows "run around" the barrel-shaped surface of the section 8 racks. The value of the length l of this section, which determines the height δ of the segment A _m B (see FIG. 2) for given values of R and d, is chosen so as to provide the necessary movement (and rotation) of the pillows at the maximum possible wedge-shaped formable strip. At the same time, a “margin” of the magnitude of the indicated displacement was made, taking into account the possible presence on the strip of dirt or particles of scale (with a hot-rolled billet), which increase the actual thickness of the molded billet.

An experimental verification of the proposed stand was carried out on a high-quality roll-forming mill 2 ÷ 8 × 100 ÷ 600 OJSC "Magnitogorsk Iron and Steel Works".

For this purpose, when profiling strips 4 ... 8 mm in the assortment of this mill, channel and trough profiles of various sizes were formed and the parameters of the claimed stand were varied, and a known device taken in the amount of the closest analogue was tested (see above).

The best results (yield of quality bent profiles within 99.4 ... 99.8%) were obtained with the implementation of the inventive device. Deviations from the optimal values of "l" and "D" (the value of R was taken only equal to 0.5 (L + D) to avoid jamming of the pillows during their movements) worsened the achieved indicators.

So, for l <1,2d, firstly, due to a decrease in the length of the contact surface of the pillow holes and barrel-shaped sections of the racks, their wear increased with increasing gaps, which led to longitudinal-transverse displacements of the pillows relative to the profile axis with a deterioration in the geometry of the finished profiles. Secondly, to keep the value of D unchanged (optimal, calculated by the above formula), it was necessary to increase the diameter d of the racks with an increase in the dimensions of the pillows and, accordingly, the costs. In addition, with a decrease in l, the possible skew angle of the shaft decreases (due to the stop of the upper rib of the upper pillow and the lower rib of the lower pillar when turning the pillows), which reduces the capabilities of the device.

For l> 1,2d and D = const, it is necessary to maintain the required angle of skew of the upper roll to reduce the value of d, which weakens the racks.

Since at R = const the values of l and D are interrelated, a decrease in D led to an inevitable decrease in l, and an increase in D led to an increase in l with the above negative consequences.

Verification of the device according to US Pat. US No. 3785191 (the closest analogue) gave an output of quality bent profiles of not more than 98.3%. Thus, the experiments confirmed the acceptability of the technical solution found to achieve the goal and its advantages over the known object.

According to technical and economic studies conducted at the Central Control Laboratory of OJSC MMK, the use of the inventive stand for the production of long bent sections at the plant will increase the yield of rolled products of grade I by at least 1 abs.% With a corresponding increase in profit from sales.

Concrete example

The stand of the roll forming mill has the structure shown in figures 1 and 2.

Stand parameters: R = 500 mm; d = 50 mm.

The maximum diameter of the barrel-shaped section of the racks:

т.е. δ=0,9 мм.

those. δ = 0.9 mm.

The value of L = 2 (R-0.5D) = 2 (500-51.8) = 896.4 mm.

Barrel height of racks:

или l=60=1,2×50=1,2d.

or l = 60 = 1.2 × 50 = 1.2d.

With the height of the upper pillows h = 250 mm, the maximum value of their rise (lowering):

that more possible maximum wedging strip workpiece, for example, section 8 × 600 ^mm2 (maximum mill for 2 ÷ 8 × 100 ÷ 600), equal to 1.25 mm if the preform is obtained by slitting a wide band 8 · 2000 mm normal accuracy rolling (see GOST 19903, table 3).

Claims (1)

A cage of a roll forming mill, mainly of high quality, containing upper and lower calibrated rolls installed in pillows placed in beds having horizontal traverses, four cylindrical guide racks of diameter d passing through the vertical holes of the pillows, and compression springs located on the racks between the upper pillows and horizontal traverses of the bed, characterized in that the guide racks are made with a barrel-shaped located symmetrically with respect to the horizontal axis of the upper roll area with a circular generatrix of the surface, the radius of which R is defined by the expression: R = 0.5 (L + D), where L is the horizontal distance between the centers of the cross sections of the pillows;

- the maximum diameter of the barrel-shaped portion of the uprights, and the length of the specified portion is 1.2d.

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