RU2812165C1 - Piercer roll - Google Patents

Abstract

FIELD: milling.

SUBSTANCE: piercer roll. The roll contains a guide section, input and output cones. On the guide section there is a protrusion in the form of a radial ridge. Using mathematical relationships, the guide section of length L₁ and the angle of the guide section generatrix with the rolling axis were calculated α₁.

EFFECT: stable grip of the workpiece by the rollers of the piercer roll is ensured, its centering along the rolling axis at the moment of gripping the workpiece by the rolls and a reduction in the thickness difference of the pipe workpiece during rolling by rolls.

4 cl, 2 tbl, 3 dwg

Description

The invention relates to pipe rolling production, in particular to the working tools of cross-helical rolling piercing mills, used in the production of sleeves for pipe production.

A known roller for a piercing mill (RF patent No. 2220796, B21B 27/02, B21B 19/04, publ. 01/10/2004), which has a section for connection to the drive, two support journals for bearings, a working section consisting of inlet and outlet cones , and a working section that serves to center the liner at the exit from the deformation zone, located in a cantilever on the output side of the roll.

The disadvantage of the roll is that deviation from the rolling axis can occur not only at the exit from the deformation zone, but also at the entrance, resulting in wear and/or inaccurate adjustment of the input side of the piercing mill equipment, which leads to curvature of the workpiece and end flow of metal , in this case, the mandrel nose and the mandrel enter the workpiece with a deviation from its center, which contributes to the difference in thickness of the sleeve and the finished pipe.

A known roll for screw rolling of pipes (AS USSR No. 973200 V21V 27/02, V21V 19/04, publ. 11/15/1982), adopted as a prototype, which contains inlet and outlet cones and has a protrusion that is made on part of the surface the input cone of the roll and has a profile along the axis of the roll, limited by a second-order curve conjugate with the generatrix of the input cone.

The disadvantage of the roll is that the protrusion made on the surface of the roll input cone forms an eccentricity; upon contact with the rolls, the workpiece deviates from the rolling axis, its grip by the rolls worsens and the workpiece axis shifts relative to the rolling axis, which leads to variations in thickness and the formation of internal defects. The helical cavity formed by the protrusion of the roll on the surface of the workpiece can lead to metal rolling during the piercing process.

The technical objective of the invention is to develop a design for a piercing mill roll that ensures centering of the workpiece along the rolling axis at the moment of gripping by the rolls by increasing the retracting forces during gripping.

The technical result consists in ensuring stable grip of the workpiece by the rollers by creating additional contact at the inlet section, which reduces the difference in thickness and the formation of defects on the inner surface of the sleeve.

This technical result is achieved due to the fact that the piercing mill roll contains input and output cones and a protrusion. According to the invention, on the input side of the roll there is a guide section of length L ₁ , calculated by the formula:

Where - outer diameter of the workpiece being stitched, mm;

- coefficient taking into account the geometric parameters of the technological tool,

the angle of its generatrix with the rolling axis is

Where - coefficient taking into account the rolling angle of the piercing mill rolls,

ρ - rolling angle of piercing mill rolls, degrees,

in this case, the protrusion is located on the guide section and is made in the form of a radial ridge.

In a particular case, the radius ridge is made with radius R and height H, calculated using the following formulas:

Where - coefficient taking into account the type of workpiece,

- coefficient taking into account the settings of the piercing mill.

In a particular case, the guide section of the roll is made cylindrical.

In a particular case, the guide section of the roll is made conical.

The implementation of a guide section on the input side of the roll with a length L ₁ , calculated by formula (1), limits the degree of freedom of the specified workpiece and ensures a smoother feeding of the workpiece into the rolls. The angle of the guide section generatrix with the rolling axis is which ensures, when turning and installing the rolls into the mill, the parallelism of the generatrix of the guide section of the rolling axis and the maximum area of contact with the workpiece. The location of the radius ridge on the guide section ensures stable gripping of the workpiece by the rolls due to increased retracting forces during gripping and additional contact at the input section and centering it along the rolling axis at the moment the workpiece is captured by the rolls, due to which the variation in thickness of the liner is reduced and the quality of the resulting liners is improved.

It is preferable to make a radius ridge of radius R and height H, calculated according to formulas (3) and (4), to obtain the maximum possible limitation of the degree of freedom of the workpiece and ensure smooth and unhindered feeding of the workpiece into the rolls of the piercing mill.

The selection of coefficients taking into account the geometric parameters of the technological tool _k1 , the rolling angle of the piercing mill rolls k, the type of workpiece _k2 and the settings of the piercing mill _k3 , was carried out experimentally by repeated measurements of the resulting sleeve when rolling workpieces of various assortments, taking into account curvature, actual diameter, state of the outer surface of the workpiece and with various parameters of the piercing mill settings.

During the period of initial capture of the workpiece by rolls and contact of the workpiece with the radius ridges, the peak load on the piercing mill drives decreases, which ensures a more gentle operating mode of the equipment, and, as a result, a decrease in the likelihood of breakdowns.

The proposed calibration of the rolls has a positive effect on the implementation of secondary gripping of workpieces due to additional contact with the radius ridges on the guide section of the rolls, which allows reducing the number of deformation cycles before the workpiece meets the mandrel, increasing the accuracy of geometric parameters and the quality of the sleeves.

The present invention is illustrated graphically, where in Fig. 1 schematically shows a longitudinal section of a piercing mill roll; FIG. 2 shows view A of FIG. 1, in fig. 3 - location of the rolls of the proposed design before filling the deformation zone with metal.

The roller 1 contains on the input side a guide section 2, on which a radius ridge 3 is made, a working section consisting of an input 4 and an output 5 cones. The guide section 2 is made of length L ₁ , calculated by formula (1), the angle of the guide section 2 with the rolling axis is α ₁ , calculated by formula (2). The radial ridge 3 is preferably made with a radius R and a height H, the values of which are calculated using formulas (3) and (4), respectively.

The guide section 2 can be made cylindrical for barrel-shaped rolls or conical for mushroom-shaped and cup-shaped rolls.

The proposed piercing mill roll works as follows. Rolls 1 are installed in the mill in such a way that the generatrix of the guide section 2 is parallel to the rolling axis.

The workpiece 6, included in the rolls 1 of the piercing mill, passes through a guide section 2 of length L ₁ located along the piercing from the end of the barrel of the roll 1, the generatrix of which, when the rolls are installed in the mill, is parallel to the rolling axis. In this case, the generatrix of the guide section 2 makes an angle α ₁ with the rolling axis.

The workpiece 6 is centered on the radius ridges 3 of the rolls 1 of the piercing mill, located at the same distance from the rolling axis, which is half the diameter of the heated workpiece, and then enters the input cone 4 of the roll with a length of L ₂ with a generatrix angle α ₂ for primary capture before the mandrel 7. Radius ridges 3 made on the rollers hold the workpiece 6 exactly along the rolling axis, ensuring stable grip and centering of the workpiece along the rolling axis at the moment of gripping by the rolls without opening the internal cavity.

It is the implementation of the roll with a guide section of length L ₁ , calculated according to formula (1), the generatrix of which makes an angle α ₁ with the rolling axis, and a radius ridge, mainly with parameters calculated according to formulas (3) and (4), that ensures stable grip of the workpiece by increasing the retracting forces during gripping and additional contact at the inlet section of the rolls and centering it along the rolling axis at the moment of gripping by the rolls, which reduces the variation in thickness and curvature of the rolled sleeve and the formation of defects on its inner surface.

The proposed piercing mill roller was tested in the production of seamless pipes with a diameter of 168÷273 mm, obtained from a continuously cast billet (hereinafter referred to as a continuous cast billet) with a diameter of 290 mm (Table 1), and with a diameter of 325 mm, obtained from a continuous cast billet with a diameter of 360 mm (Table 2) . To compare the results on metal loss (defects, second grade and defect cutting) and liner curvature, we used the indicators of products obtained using the current technology.

The use of the proposed roll design made it possible to ensure stable gripping of the workpiece by the rollers of the piercing mill due to increased retracting forces during gripping and additional contact at the inlet section of the rolls, centering the workpiece along the rolling axis at the moment of gripping by the rolls and reducing the level of metal losses during pipe production due to the main types of defects, including including:

- for the defect “internal rolling film” when rolling pipes from continuous-cast mill:

with a diameter of 290 mm - from 0.32 to 0.22%,

with a diameter of 360 mm - from 0.89 to 0.45%,

- in the production of pipes with a diameter of 325 mm, reduce the deviation in wall thickness from the permissible value from 0.61 to 0.35%.

In addition, the number of defects has been reduced, as well as technological waste at the first stage.

The use of the proposed roll of the piercing mill of cross-helical rolling will ensure stable grip of the workpiece by the rolls of the piercing mill, centering it along the rolling axis at the moment of gripping by the rolls and reduce the variation in thickness of the sleeve, deviations in wall thickness from the permissible value, the curvature of the rolled sleeve and the formation of defects on its inner surface .

Claims (15)

1. A piercing mill roll containing input and output cones and a protrusion, characterized in that on the input side of the roll there is a guide section of length L1, calculated by the formula: Where - outer diameter of the workpiece being stitched, mm; - coefficient taking into account the geometric parameters of the technological tool, the angle of its generatrix with the rolling axis is Where - coefficient taking into account the rolling angle of the piercing mill rolls, ρ - rolling angle of piercing mill rolls, degrees, in this case, the protrusion is located on the guide section and is made in the form of a radial ridge. 2. Roll according to claim 1, characterized in that the radius ridge is made of radius R and height H, calculated according to the following formulas: Where - coefficient taking into account the type of workpiece, - coefficient taking into account the settings of the piercing mill. 3. Roll according to claim 1 or 2, characterized in that the guide section of the roll is made cylindrical. 4. Roll according to claim 1 or 2, characterized in that the guide section of the roll is made conical.

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