SU1715464A1 - Tube cold rolling mill - Google Patents

Abstract

This invention relates to pipe production. The purpose of the invention is to increase the geometric accuracy of the pipes and the service life of the mill. In the cold tube rolling mill, working stand 1 is mounted on supports 2 in guides 4 of frame 3, having an upper opening for removing the stand. The gaps between the supports and the rails in the vertical plane are 0.008-0.012, and in the horizontal plane they are 0.0036-0.0044 for the diameter of the roll gauge. As a result, the stand distortion and jamming of the stand are eliminated, the geometrical accuracy of the pipes and the service life of the mill are increased. 1 il.

Description

The invention relates to pipe production and can be used on periodic cold rolling mills.

The purpose of the invention is to increase the geometric accuracy of the pipes and the service life of the mill.

The drawing shows the proposed mill cold rolling tubes, cross-section.

The cold rolling mill tube contains a working stand 1 with supporting rollers 2 mounted on it, moving in frame 3 along supporting rails 4 attached to it. The stand in the frame is installed (and removed from it) vertically down (and up). In stand 1, calibration rolls 5 are mounted. Cage 1 and guide beds 3 are equipped with 6 friction contact plates. From below, stand 1 has additional idler rollers 7, which are freely rotatably mounted on 2 shafts common with rollers, and base 3 above rollers 7 has removable rigid guides (friction plates) 8, and the axis of each roller 7 is coaxially continuing the axis of their roller 2. The mill also contains as a drive mechanisms for moving the stand, feeding and turning the workpiece and the mandrel, the front and intermediate cartridges (not shown).

The location of stand 1 in frame 3 is governed by the following gaps between the supports of the stand and the bed guides:

the clearance L in the vertical plane between the roller 7 and the lower edge of the rail 8 of the bed 3, while

D (0.008-0.012) 0; (1)

cl

Ј

J

a two-sided clearance D in the horizontal plane, equal to the sum of the one-sided clearances DG1 and Ag2 between the working stand 1 and the guide frame 3 (between the plates 6),

DgЈ Dm + D g2 (0.0036-0.0044) 0 (2) where D is the diameter of the caliber.

When selecting the exorbitant values of the regulated gaps (in the vertical and horizontal planes) lower than their lower limit (respectively, less than 0.008 D and 0.0036 D), the service life of the HPT mill (and, consequently, its performance also for repair and restoration) is sharply reduced due to intense wear of the guide and deflection of the support axes of the rollers, which simultaneously causes a displacement of the rolling axis from the mill axis, and hence the deterioration of the geometric accuracy of the pipes and the occurrence of scrap. |

When choosing extreme values of regulated gaps (in the vertical and horizontal planes) larger than their upper limit (respectively more than 0.012 D and 0.0044 D) increases and goes beyond the limits of the permitted freedom of play in the stand of the stand and unpredictable and unacceptable distortions and increased deviations occur from the straightness of movement, and the rolling axes - from the mill axis, which increases the waviness and curvature of rolled pipes beyond the allowable limits by 1.5-2.2 times, which increases the loss of metal in the marriage, reduces the yield of uktsii forces and for contraction marriage dramatically reduce pitch and linear displacement of the metal during rolling, as well as their dependent mill productivity.

Installation of values of gaps in vertical (A) and in horizontal (Agx Ag1 + Ag2 - - to) PLANES

respectively, between elements 7 and 8 and between elements 6 are carried out as follows.

First, the required pipe sizes are selected from the gauge, and for them, the corresponding value of the diameter D of the gauge, according to which, taking into account the average (optimal) values of the coefficients, respectively, 0.010 and 0.0040, the values of Аi and Art are calculated using mathematical expressions (1) and (2) respectively.

In a stopped mill, i.e. when the drive is off, the calculated values

D. Ai and Ari Ar2 - - set

between the corresponding elements of the camp,

The mill is ready for pipe rolling, for working with regulated guaranteed gaps in the vertical and horizontal planes between the bed guides and stand supports.

Example. The guaranteed guaranteed clearances between the cage and the bed (in the zone of their contact) were tested in the production of bearing tubes made of steel ShKh 15 in the HPT mill with a distribution-feeding mechanism of a reducer type and with a double-roll working stand of a closed type installed in the frame and removed her upright. The movement supports of the cage were made in the direction of the main rollers with a working diameter of 250 mm moving along the support rails of the bed. On the same axis with the main rollers, there are freely additional rolling bearings with a diameter of also 250 mm, which are contact points with a guide bar (in the frame) that limits the vertical movement of the stand. When testing, we used calibrated rolls with half disk caliber with a diameter of D 434 mm. The size of the technological gap between the calibrated rolls was 1.0 mm.

The values of the proposed gaps calculated from expressions (1) and (2) were: Дь (0.008-0.012) D 3.47 .- .. 5.2; Dsr 0,010 D 4,34 mm; Fgg (0.0036-0.0044) D 1.56-1.91 mm; A-Ј cf. 0.0400 1.74 mm.

The tests were carried out by rolling along the route 76x10- 43.0x7.5 mm in the number of double cages per minute, equal to 60, with a metal stretching ratio of 2.35 and with feeding the metal into calibers per rolling cycle, equal to 14-17 mm.

The invention makes it possible to increase the geometrical accuracy of the pipes with respect to straightness by reducing the waviness of the pipes by 1.2-1.5 times and reducing the curvature by 1.5-2.0 times. At the same time, an increase in the mill service life is also achieved by a factor of 7–8 due to an increase in the durability of the main parts of the support assembly of the working stand and a decrease in the wear of the guide frame under the working stand. In addition, the possibility arises of increasing the feed and linear displacement of the metal per rolling cycle by 1.8-1.22 times without reducing the geometric accuracy of the pipes, which makes it possible to increase the efficiency of the mill using a corresponding increase in its productivity (by 1.18-1.22 times).

Optimal results were achieved when testing the average values of Dsr and Aggsr gaps from their proposed

limits.

Thus, tests conducted by the invention have revealed the feasibility of using in the production of cold-rolled pipes at HPT mills technological gaps regulated on a technological basis not only between calibrated rollers, but also between the working stand and bed guides under it.

Claims (1)

Claims: Cold tube rolling mill comprising a frame with guides and upper opening and a working stand with vertical removal from the frame and with calibrated rollers, mounted in guides on supports with regulated gaps between the supports and guides in the vertical and horizontal planes, characterized in that, in order to improve the geometrical accuracy of the pipes and the service life of the mill, the gaps in the vertical plane are 0.008-0.012, and in the horizontal plane 0.0036-0.0044 of diameter libra. w-h