Calibration of rolls for rolling round profiles. Rolling and calibrating rolls to obtain products of round and square section How to roll a square from a circle yourself

1. The profile of the hole, images, adjacent streams of rolls in the working position and the gaps between them, serves to give a given shape and size to the section of the roll. Usually k. is formed by two, less often - by three and four rolls. The shape can be simple - rectangular, round, square, rhombus, oval, strip, hexagonal, lancet and shaped - corner, I-beam, channel, etc. By design, i.e. the position of the parting line, which is divided into open. and closed, according to the location on the rolls - open, closed, semi-closed. and diagonal. By appointment - crimping, exhaust, roughing, pre-finishing and finishing k. Osn. el-you k. - gap m-du rolls, outlet k., connector, collars, rounded, neutral. line. Types of k. are shown in fig. 2. Replaceable technological tool, fix on the work roll. 3. Scaleless measure, a tool for controlling the size, shape and relative position of the parts of the product by comparing the size of the product with k. according to the occurrence or degree of fit of their surfaces:
beam gauge - k. (1.) for rolling rough and finishing I-beams. Use b. to. direct closed, open, tilt, and univers. Usually two-roll are used, less often - universal. four-roll b. k. Naib, distribution. direct closures b. to. Open. b. used as cutting and roughing when rolling large I-beams. Tilt, b. to. I-beam profiles are rolled with a decrease. slopes inside. edges of shelves and large flange heights. To the uni. b. k. wide-shelf I-beams of large sizes and I-beams with parall are rolled. shelves. When rolling lightweight I-beams, a horizon is used, position. diagonal. b. To.;
drawing caliber - k. (1.) of a simple form to reduce the cross section and hood (1.) of the roll with a given alternation of two or one caliber of the same type. In a number of cases, in to. give the roll dimensions, at which the formation of a given profile begins. When rolling simple profiles, they are usually draft gauges. In quality-ve in. used rectangular, square, rhombic, oval, hexagonal. and other calibers. Depending on the rolling conditions and requirements, the section of the rolled c. to. are located in the definition. last, naming. exhaust caliber system;
diagonal caliber - closed to. (1.) with a diagonal. (different in height) located. connectors. D. to. usually cut into rolls with an inclination and are used for oblique calibration of I-beams, profiles and rails. Horizon, d. to. is used when rolling I-beams, profiles on continuous mills and Z-profiles. D. to. facilitates the exit of the roll from the rolls, but creates undesirable. side forces;
closed caliber - k. (1.), in which the parting line of the rolls is outside its contour. 3. k. are usually used for rolling shaped profiles; he, as a rule, has one vertex, an axis of symmetry;
Ribbed oval gauge
rhombic caliber - k. (1.) rhombic. config., embedded in the rolls along a small diagonal. Calculation, dimensions: C, \u003d 5K / 2sinp / 2, B - B - Sa, height taking into account rounding

Rhombic caliber
R, = R, -2K(1 + l/ek2) -1), a = R/R, = = tgp/2, / = (0.15-n0.20) R1, l, = (0.10 + 0.15) R " R \u003d 2 (R, 2 + R, 2) "2, in, \u003d 1.2 * 2.5 (Fig.). R. to. is used in the rhombus-rhombus and rhombus calibration system -square The angle at the top of the groove p varies from 90 to 130°, with an increase in the angle of increased drawing in the groove, averaging 1.2-1.3. -0.9;
Lancet square gauge
lancet square caliber - k. (1.) with the contour of a square with concave sides, cut into the rolls diagonally. Calculation, dimensions: Bk \u003d R, \u003d 1.41 C,; R = = (C,2 + 4D2)/8D; r \u003d (0.15 + 0.20) C,; B \u003d 5K - (2/3) 5. Area F \u003d C, (C, + (8/3) D), where D is the value of one-sided. convexity, C, - the side is inscribed, square (fig.). Max, side size c. c.c. C^ = C, + 2D. S. to. to. apply when necessary. transfer a large amount of metal to the finishing passes. At the same time, the output is preserved. roll temperature, because there are no sharp corners. S. to. to. - exhaust in the system of calibers oval-lancet square and sometimes pre-finishing for circles;
draft gauge - c. (1.), approx. section of the workpiece or roll to the configuration of the finished profile. Ch. to. shaped profiles in the course of rolling approach the finish k. The shape of the c. to. when rolling simple profiles is determined by the exhaust system of the k.
finishing gauge i-k. (1.) to give the roll a final profile, i.e. for the manufacture rental from the end transverse dimensions. sections. When constructing h. to. take into account thermal expansion. metal, uneven distribution of pred. temperatures in the roll, wear of calibers, profile correction, and other factors;
hex gauge - k. (1.) hex. contour, cut, into rolls along a large diagonal. Connector sh. to. is located on its sides. Dimensions w. k. exp. through vpi-

Hex gauge
dignity. circle diam. d: side C \u003d 0.577d, area -F \u003d 0.866d2, height R, \u003d 2 C (Fig.). Appl. it is clean in quality, caliber when rolling is six-tigran. steel and black. when rolling a hexagon. drill steel, when uniform and low reduction along the passes is required;

Square caliber
hexagonal caliber - k. (1.) hexagonal. contour, cut, into rolls along the minor axis; appl. in the exhaust system of calibers hexagon-square and as pre-clean. when rolling hexagonal profiles. Calculation, dimensions: 5D = 5K - I,; B \u003d 5K - S; ak = BJH, = 2.0+4.5; r \u003d r, \u003d (OD5 + 0.40) R,; Р = 2(Bf + 0.41R,) (Fig.). Predchistovoy sh. to. build as usual hexagonal, but for compensation. broadening of the metal and preventing. convexity of the side walls is clean. the hexagon bottom of the caliber is made with a convexity of 0.25-1.5 mm, depending on the size of the profile. Degree of filling sh. to. take 0.9;
l

box caliber
box caliber - k. (1.), images. trapez. cuts in rolls, for rolling pryamoug. and square, profiles. Estimated dimensions: 5d \u003d (0.95 + 1.00) V "; B \u003d Yad + (I, - S) tg (p; g \u003d (0.10h-0.15) I,; g, \u003d (0.8 + 1.0) / -, ok \u003d \u003d 4 / I , = 0.5 + 2.5; /> * 2(R, + B,) (Fig.) The depth of the cut, i.k., R, depends on the ratio of dimensions (R, / 00) of the profile specified in it. used mainly on blooming, swaging and continuous blanking mills, swaging, and blackening stands section mills and for the production of commercial blanks on rail and beam mills.
square gauge - k. (1.)
square, contour, cut into rolls along dia
chased. Depending on the requirements, rental profile
performed with rounded or sharp tops
us. Calculation, dimensions: Hk \u003d Bf \u003d 21/2 C I, \u003d
\u003d 21/2 C. - 0.83 g, B \u003d B-s; r \u003d (0.1 + 0.2) ^;
/-,= (0.10^0.15)I,; P \u003d 2-21 / 2I, (Fig.). K. to. -
finishing when rolling square pro
lei and exhaust in rhombus-square systems,
oval-square and hexagon-square. In black
new calibers perform significant
rounding of the vertices with a radius of r. The height and width of the c. c. are, respectively, 1.40 and 1.43 of its sides.
When rolling squares with sharp corners, the k.k. has an angle at the top of the example, but 91-92 °, taking into account
volume of thermal shrinkage of the profile; L""" ° t -""" """ and
control caliber - to. (1.), for small high-rise compression and control of the sizes otd. el-tov peal; used when rolling a number of shaped and complex profiles, for example, I-beams, for wheel rims, door hinges, etc. K. to. perform closed and semi-closed. Closed to. to. provides more accurate dimensions of rolled elements, but more often they work with semi-closed to. to. In a closed to. to., the flange is crimped only in height, and in a semi-closed - in height and thickness in the open part of the caliber;
round caliber - k. (1.) with a circle contour on the main part of the perimeter; finishing when rolling round steel and exhaust in the oval-circle system. K. to. all types have a release or collapse. When constructing a finishing k. to., they usually take an outlet of 10-30 ° or 20-50 °, depending on the diameter. rolling circle. Estimated dimensions: Bf \u003d rf / cozy, B " \u003d Yak-. Stgy, g, \u003d (0.08 + 0, lO) d, P \u003d \u003d tk / (fig.). Since they tend to roll round steel with minus, tolerance D on dia., then for finishing k. to., taking into account thermal expansion, they take d \u003d 1.013, where rfxon "~ Diam. circle in a cold state;
multi-roll caliber - k. (1.) with a contour formed by three or more rolls, the axes of which lie in the same plane. In m.k., the metal is crimped in the vertical-transverse direction. with advantage all-round compression, which allows you to deform low-plastic materials. M. to. high dimensional accuracy of the profiles, therefore they are widely used in the finishing stands of small-section and wire mills for rolling steel and non-ferrous. metals. Four-roll open and closed calibers are often used for mountains. and hol. rolling of high-precision shaped profiles;
swaging caliber - k. (1.) to reduce the cross section of the roll and obtain blanks for section mills. In quality about. to. on blooming, swaging and billet mills use box calibers. Deformation in about. k. is not always accompanied by creatures, an exhaust, as, for example, in the first passes on blooming. However, to Fr. to. sometimes partially or completely include calibers exhaust systems calibrations. Subsection, calibers for swaging and drawing depends on the purpose of the rolling mill, the system of calibers and a separate caliber;
oval caliber - k. (1.) of an oval or close to it contour, cut into rolls along a minor axis. O. to. used as a pre-finishing when rolling round profiles and exhaust in the system oval - rib oval, etc. Depending on the purpose of the caliber and size of the rolls, they use: 1. Single-radius about. to. (usual o.k.), app. as pre-finishing when rolling round steel. Their calculated dimensions (Fig.): R = R, + (1 + O/4; B = (R, - S) 1/2; r, = (0.10 + 0.40) ^; P = 2 [B* + + (4/3)R,2]1/2; when rolling large circles and in oval-circle and oval-oval systems; flat o.k., used in the same place as elliptical o.k. to-rykh B = OD, r = 0.5R, r = (0.2 + 0.4)R, O|t = 1.8 + 3.0, modified flat o.c., the contour of which is an image, a rectangle and lateral curvilinear triangles, taken as parabolic segments; trapezoidal (hexagonal) OK with straight outlines, used for good retention of the roll and alignment of the hoods
open caliber - k. (1.), parting line to-rogo within its contour; image, cuts in two or more rolls, cuts in one roll and a smooth barrel or smooth barrels. In simple o. to. connector image, approximately in the middle of the caliber and the side sections of the roll forming. shoulders of two rolls. In some shaped about. to. they form. stream walls in only one swath;
semi-closed caliber - shaped to. (1.) with the location of the connector on the side wall near the top of the stream; used as a control when rolling channels, strip bulbous, I-beam and other profiles. Compared to a closed control pass, it has a larger outlet and a shallow depth of cut in a closed stream, which weakens the roll less in diameter, allows you to compress the flanges of the rolls in thickness, increase the number of regrinds and the service life of the rolls;
pre-finishing caliber - k. (1.) for the penultimate. roll skips; to prepare the roll for forming. final profile. When rolling shaped
profiles in shape and / or size is very close to finishing, and when rolling simple profiles, it may differ. In quality-ve p. to. often used rib gauges when rolling strip profiles and control when rolling flange profiles;
split caliber - 1. K. (1.) with a crest in the middle part, for the original. for-world. from blanks of flanged rolled elements; for example, when rolling I-beams from a rectangular. blanks are formed sections of flanges and walls, and when rolling rails - sections under the sole and head. Use open and closed rivers. to. Closed r. to. carry out on rolls of big dia. for the manufacture large flanges. Open symmetrical. R. C. with blunt crests are often used for rolling beam blanks from slabs. 2. K. for the longitudinal separation of double peals;
Rib Gauge
rib caliber - k. (1.), cut, into rolls of large size; used, in particular, when rolling strip steel to control the width of the roll. Predchistovoy r. to. also forms the edges of the rolled products. When rolling strips with straight edges, the convexity of the bottom of the pre-finishing river. k.D = = 0.5-5-1.0 mm, roll gap< 1/3 высоты полосы и выпуск 0,05+0,10 (рис.);
T
ribbed oval caliber - k. (1.) oval contour, cut, into rolls along the major axis. Calculation, dimensions: R \u003d 0.25 / ^ (1 + + 1 / a2), B \u003d B- 2L, r \u003d \u003d rt \u003d (0.10 + 0.15) 5, ak \u003d 4 / R, \u003d 0 .75 * 0.85, P \u003d 2 (I, 2 + (4/3) g, T2 (Fig.). Used as an exhaust in the oval - rib oval system;

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Ministry of Education of the Republic of Belarus

Educational Institution Gomel State Technical University named after P.O. Sukhoi

Department: "Metallurgy and foundry"

Explanatory note

To the course project

course: "Theory and technology of rolling and drawing"

on the topic: "Development of calibration of rolling rolls for a round profile with a diameter of 5 mm"

Made by a student of group D-41

Rudova E.V.

Checked by Ph.D. assistant professor

Bobarikin Yu.L.

Gomel 2012

1. Introduction

2. The choice of finishing calibers and the calculation of the cross-sectional areas of the roll

3. Choice of drawing calibers and calculation of sections of roll

4. Determining the dimensions of calibers

5. Calculation of the rolling speed

6. Calculation temperature regime rolling

7. Determination of the coefficient of friction

8. Calculation of rolling force

9. Calculation of rolling moment and power

caliber section profile rolling rolls

1 . Introduction

The basis of section rolling production technologies is the plastic deformation of metal in various types calibers of rolling mill rolls.

Section profiles are rolled from a billet in several passes in the calibers of rolling rolls, which give the rolled metal the required shapes. For the production by rolling of a metal assortment of a simple and shaped profile (round, square, hexagonal, strip, angular, channel, tee, etc.), it is necessary to calculate the calibration of rolling rolls.

Calibration of rolls called the definition of forms of dimensions and the number of calibers measured on rolls to obtain a finished profile.

Roll gauge- this is the gap formed by cuts in the rolls or a stream in a vertical plane passing through the axes of the rolls.

Calibration should ensure rolling from a billet of the required profile of the required shape and dimensions within the accepted tolerances, as well as good quality rolled products, maximum rolling productivity, minimum wear and energy consumption spent on the operation of the rolling mill.

Profile rolling is initially carried out in drawing calibers designed only to reduce the cross-sectional area of ​​the rolled billet. With a decrease in the cross-sectional area of ​​the workpiece, the latter is stretched in length without approaching the cross-sectional shape of the strip to the required one, therefore these calibers are called exhaust. After passing through the drawing passes, the workpiece is rolled in the finishing passes. Finishing calibers are divided into pre-finishing and finishing calibers. In pre-finishing gauges (there may be several or one), with a further decrease in area, the configuration of the section approaches the given shape of the finished profile, and its individual elements are formed. In the finishing pass (it is always the same), the required shapes and size of the profile are finally formed, it is placed on the last rolling pass.

2. The choice of finishing calibers and the calculation of cross-sectional areaseny peal

Choice of quantitytva and forms of finishing calibers

The number and shape of the finishing gauges, i.e. finishing and pre-finishing gauges, depends on the shape of the finished or final profile and on the accepted finishing gauge calibration system.

For a round profile, the finishing gauges are the pre-finishing oval gauge and the finishing round gauge. After the pre-finishing oval pass, the roll of the oval profile passes through 90° tilting and enters the finishing round pass, where the round profile is finally formed (Figure 2.1). In this case, the shape of the pre-finishing oval caliber depends on the dimensions of the finishing profile. The figure shows a pre-finishing oval gauge for medium and small finishing profile sizes.

Rice. 2.1 Scheme of finishing calibers of a round profile

The turning of the roll can be carried out with the help of special turning wires between rolling stands for continuous mills or turning devices, between rolling passes for foundry mills. In addition, on continuous mills, the condition of turning by 90° can be carried out by alternating roll stands with horizontal and vertical arrangement of the axes of the rolls.

For rolling a round profile in the group of finishing calibers, a finishing round and pre-finishing oval calibers are used.

Determination of the dimensions of the final profile in the hot stateIresearch institutes

To increase the service life of the calibers, the calculation is made to obtain a profile with minus tolerances of its dimensions. In order to take into account the reduction in the dimensions of the profile rolled in the hot state during cooling, it is necessary to multiply the size of the profile in the cold state by the coefficient 1,01-1,015 .

Taking a minus tolerance for a round end profile, we find the size of the circle in the cold state:

Hot Finishing Wheel Size:

Determination of elongation coefficients in finishing calibers.

For finishing round caliber elongation coefficient where k is the number of finishing calibers, and also for the pre-finishing oval caliber, we determine according to the graph in fig. 2.2.

Fig. 2.2 The dependence of the elongation coefficients in the finishing circle, as well as in the pre-finishing oval, on the corresponding circle diameter .

Note: if a round profile with a diameter of less than 12 mm inclusive is rolled, then the elongation coefficients in the finishing and pre-finishing passes are determined according to practical recommendations for a specific profile. Taking into account the structural features of the rolling mill 150 BMZ, we take the average drawing equal to 1.25.

Determination of cross-sectional areas of profiles in finishing potsbrah.

The areas of profiles in finishing calibers are determined by the dependencies:

where is the cross-sectional area of ​​rolled products in the finishing caliber, determined by

according to the hot dimensions of the final profile; - cross-sectional area of ​​the roll in the last pre-finishing pass; - cross-sectional area of ​​the roll in the penultimate pre-finishing pass. Let us determine the cross-sectional area of ​​the strip in a finishing round pass:

The cross-sectional area of ​​the strip in the pre-finishing oval caliber is:

The cross-sectional area in the last draft pass and, accordingly, in the last pass of rolling of the drawing group of passes, is determined by the formula:

3. Choice of drawing calibers andcalculation of the cross-sectional areas of the roll

Selecting a drawing system

As a rule, drawing calibers are formed according to certain systems, which are determined by the alternating shape of the calibers of the same type.

Each draw gauge system is characterized by its pair of draw gauges, which determines the name of the draw gauge system.

Pair of drawing calibers- these are two successive calibers in which the workpiece from an equiaxed state in the first caliber approaches a non-equiaxed one, and in the second one again into an equiaxed one, but with a decrease in the cross-sectional area.

The following systems of drawing calibers are used: rectangular caliber system, rectangle-smooth barrel system, oval-square system, rhombus-square system, rhombus-rhombus system, square-square, universal system, combined system, oval-circle system, oval-ribbed oval system.

On small- and medium-section modern continuous rolling mills, systems are more often used: rhombus-square, oval-square, oval-circle and oval-ribbed oval.

These sizing systems ensure good quality of rolled products and a stable position of the roll in the calibers.

When rolling in drawing calibers, the roll is always tilted or rotated around its longitudinal axis at a certain angle (usually 45° or 90 °) at the transition of the roll between the stands from the first caliber of a pair of calibers to another caliber.

Turning can be replaced by alternating horizontal and vertical rolling stands, which provides a turning effect without turning the workpiece.

Turning the roll or alternating horizontal and vertical rolling stands or rolls is necessary to transfer the uneven state of the workpiece after the passage of the first caliber of a pair of drawing calibers into an equiaxed state in the second caliber of the pair.

One of the most promising sizing systems is the oval - ribbed oval system, which provides a stable rolling mode and good quality of rolled products.

In this system, in oval calibers, the workpiece goes into an unequal oval state with a large difference in the dimensions of the oval axes, and in ribbed oval calibers, into an equiaxed oval state with a small difference in the dimensions of the axes after deformation of the previous unequal oval along the major axis. Thus, the workpiece sequentially passes through the types of calibers: oval - ribbed oval - oval - ribbed oval, etc. until the required reduction in the section of the workpiece is obtained.

Determination of the average extract inarah drawing calibers and numbersrolling passes.

To determine the number of rolling passes n First, we determine the estimated number of pairs of drawing calibers:

where is the cross-sectional area of ​​the workpiece in the hot state;

Sectional area of ​​the workpiece in the last drawing pass.

Having determined the exact number of pairs of drawing calibers, then it is necessary to set the corrected value of the average drawing for a pair of drawing calibers

The number of rolling passes in drawing passes is:

The number of rolling passes for the entire rolling technology is:

Where To- the number of finishing calibers.

Here it is necessary to check whether the total number of rolling passes will exceed the number of rolling stands of the mill according to the inequality:

Where With- the number of rolling stands of the mill.

The cross-sectional area of ​​the workpiece in the hot state, taking into account the wide tolerance for the cross-sectional size, is determined by the nominal cross-sectional size:

For the oval system - rib oval. Accept.

The calculated number of pairs of drawing calibers is:

We accept the exact number of pairs of drawing calibers.

The corrected value of the average drawing for a pair of drawing calibers is equal to:

The number of rolling passes in drawing passes according to (3.3) is:

The number of rolling passes is:

Let us check condition (3.4): .

The results of the distribution of rolling passes and types of calibers by mill stands are entered in Table 3.1.

Definition of hoods for pairs of hoods.

The extract of each pair of calibers is determined by the dependence:

where is the change in the value

When making changes in the values ​​of extracts for each pair of calibers, it is necessary to take into account the equality 0 of the algebraic sum of all changes, i.e. condition must be met:

Let us determine the extracts for each pair of calibers, taking into account their redistribution, so that the initial pairs of calibers would have big values hoods, and the latter are smaller.

We will make changes for each pair of calibers according to expression (3.5), remembering that the algebraic sum of these changes should be equal to 0:

Determination of hoods by rolling passes in the hood systemandcalibers

Let's define hoods for edge ovals with the known formula:

Extracts for ovals are determined by the formula:

Using formulas (3.7) and (3.8), we determine the numerical values ​​of drawings for all passes of rolling along drawing passes:

For j= 7(14;13)

All hood values ​​for drawing and finishing calibers are entered in Table 3.1.

Determination of the cross-sectional areas of the roll in drawing calibers.

Let us determine the cross-sectional areas of the roll after each rolling pass according to the formula:

where is the cross-sectional area of ​​the roll;

The area of ​​the rolled section following in the course of rolling;

Extraction in the next caliber in the course of rolling.

By condition, after the last, i.e. 26th, pass, the cross-sectional area of ​​the roll should be equal to 28.35 . Thus, for.

The cross-sectional area of ​​the workpiece before the first pass is equal to the cross-sectional area of ​​the original workpiece. This value must be obtained from the product. However, due to the accumulation of rounding errors in the calculations, in order to accurately obtain the value, it is necessary to correct the extrusion value in the first pass:

The obtained values ​​of the cross-sectional areas of the roll for all rolling passes are entered in Table 3.1.

Table 3.1 Calibration table

		Type of caliber		Cross-sectional area F,
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		oval
		Rib oval
		Prefinishing oval
		Finish round

4. Determining the dimensions of calibers

The scheme for constructing a finishing round K-th caliber is shown in Fig. 4.1. The diagram shows following sizes: - diameter or height of the caliber, equal to the hot dimension of the diameter of the final profile round bars; - inter-roll gap; - caliber release angle; - caliber width.

Fig. 4.1 Scheme of a round caliber

The value of the inter-roll gap is determined by the formula:

The width of the gauge and the width of the strip will be equal to the diameter of the gauge.

Values ​​and select the following:

The scheme for constructing a pre-finishing oval (K-1) - th caliber of rolling an oval strip intended for subsequent rolling in a finishing round caliber of a round profile with a diameter of not more than 80 mm is shown in fig. 4.2. Let's make calculations of all necessary sizes:

Fig. 4.2 Scheme of the oval caliber

The height of the caliber is equal to the height of the strip, which is determined by the formula:

where is the cold diameter of the rolled finishing round profile;

Coefficient that takes into account the broadening of the oval strip in the finishing round caliber.

The blunting of the strip is determined by the formula:

Rice. 4.3 Dependence of the coefficient on the width of the ribbed oval strip preceding the ribbed oval gauge

The bandwidth is determined by the formula:

where is the cross-sectional area of ​​the oval strip after the passage of the pre-finishing oval caliber. The outline radius of the pre-finishing oval gauge is determined by the formula:

We assign the value of the inter-roll gap:

The gauge width is determined by the formula:

We determine the fill factor of the caliber:

The value must be within the limits.

The main dimensions of the finishing and pre-finishing calibers are entered in Table 4.1.

Construction of drawing calibers.

For the system of drawing calibers oval - ribbed oval, first we build all ribbed oval calibers according to the scheme of Fig. 4.4 and the calculation below. When rolling a square profile, the last one in the course of rolling is an equiaxed square caliber, and at the same time it is a pre-finishing square caliber. In our case, the initial profile of the rolled billet is square, so for convenient gripping of the billet, we build the first equiaxed pass along the rolling course according to the scheme of Fig. 4.4. Then we build all oval calibers according to the scheme of Fig. 4.2. and the calculation below.

Rice. 4.4. Diagram of a ribbed oval gauge

For all ribbed oval gauges, i.e. for all - x calibers, the dimensions of the caliber are determined in the following sequence.

Calculation example for caliber 26.

Width of rib oval strip

where is the cross-sectional area of ​​the rib oval strip.

Rib oval strip height

The gauge width is

where is the filling factor of the caliber, equal to 0,92…0,99 , pre-accept.

Gauge outline radius

The bluntness of the strip is:

The height of the roll gap is determined from the range, where is the diameter of the rolls of the corresponding rolling stand.

In this case, the condition

Similarly, we carry out the calculation for all other - x calibers. We enter all the main dimensions of ribbed oval calibers in table 4.1.

For all non-equiaxed calibers (Fig. 4.2.), Dimensions are determined against the rolling stroke.

For each -th non-equiaxed oval caliber, the dimensions are determined in the following sequence.

First, we determine the broadening in the equiaxed ribbed oval groove following the given caliber in the course of rolling according to the formula:

where is the broadening determined from the graph in Fig. 4.6. depending on the width of the considered rib oval strip;

The diameter of the stand rolls for a given equiaxed pass.

Fig.4.6. Dependence of the value of the broadening of the oval strip in the ribbed oval caliber on the width of the ribbed oval strip during rolling in rolls.

The height of the oval strip is:

The height of the caliber is equal to the height of the strip, i.e. .

The bluntness of the oval strip is equal to:

where is the coefficient determined from the graph in Fig. 4.3.

Preliminary value for the width of the oval strip:

where is the cross-sectional area of ​​the strip after the passage of the considered caliber.

The value of the average absolute reduction of the metal in the considered oval caliber is (for):

where is the width of the rhombic oval strip in the previous caliber under consideration.

The rolling radius of the roll is equal to:

where is the diameter of the rolls of the considered stand.

The average height of the strip at the exit to the considered caliber is equal to:

The broadening of the metal in an oval caliber is determined by the formula:

The width of the oval strip is:

The radius of the outline of the caliber is determined by the formula:

The preliminary value of the inter-roll gap will be assigned from the range, subject to the condition.

Gauge fill factor:

After that, we check the condition of normal filling of the caliber with metal.

Let's make a calculation for the 3rd non-equiaxed oval caliber according to the above formulas.

Similarly, we carry out the calculation for all the rest - calibers. The main dimensions of all intermediate oval calibers are entered in Table. 4.1.

Table 4.1. the depth of cut of the caliber is determined by the formula:

Table 4.1 Calibration table,

No. of rolling pass	Strip height	The width of the line	Caliber Height	Gauge width	Roll gap	Insertion depth

5. Calculation of the rolling speed

We determine and enter in table 5.1 all the values ​​of the rolling diameters of the rolls. In this case, for oval gauges, we define through the radii determined by the formula (4.31). For all other calibers, the rolling diameters of the rolls are determined by the formula:

where is the diameter of the barrel of rolls of the corresponding caliber;

The cross-sectional area of ​​the strip at the outlet of the corresponding caliber;

The width of the strip at the exit from the caliber.

We will carry out the calculation for 2 calibers.

Then we determine the number of revolutions per minute of the rolls in the last stand in the course of rolling according to the formula:

where is the rolling speed at the exit from the last stand, which is determined by

mill working conditions, 8 0 m/s;

Rolling roll diameter n-oh cage, mm.

where is the sectional area of ​​the strip after the passage n th stand, i.e. final rental, .

To ensure some strip tension between the stands, the calibration constant for each rolling pass must be slightly reduced as you move from the first pass to the next. Therefore, the calibration constant for the penultimate pass is:

By analogy against the rolling stroke, we determine the calibration constant for all rolling passes, i.e.

The speed of rotation of the rolls for each pass is determined by the formula:

All values ​​are entered in table 5.1.

The strip speed after each rolling pass is determined by the formula:

where in and in.

All values ​​are entered in table 5.1.

Similarly, we carry out the calculation for all other calibers, and enter all the results of the calculations in Table 5.1.

Table 5.1. Calibration table

Rolling pass	rolling diameter of rolls,	Calibration constant,	Roll speed,	lane speed,

6. Tempera calculationtour mode rolling

The task of calculating the temperature regime of rolling is to determine the temperature of the initial heating of the billet before rolling and to determine the temperature of the roll after each rolling pass.

Fine wire rolling mill 320 has the temperature of the billet at the outlet of the furnace in front of the first rolling stand 107 0 . When rolling in a 20-stand group and a wire block, the temperature of the rolled product at the outlet of this block is 1010…1070 . The heating temperature of the billet for rolling a square profile of steel 45, taking into account the table. 6.1. and technological capabilities of the mill furnace 320 take equal 12 50 , and at the exit from the 20th stand, the temperature of the rolled products is taken equal to 107 0 .

The temperature of the roll for the rolling passes is taken equal to the average, i.e.

7. Determination of the coefficient of friction

The coefficient of friction during hot rolling of metals can be determined by the formula for each rolling pass:

where is a coefficient depending on the material of the rolls; for cast-iron rolls, for steel-;

Coefficient depending on the carbon content in the rolled metal and determined from Table. 7.1. (m / s 2130 p. 60).

The coefficient depending on the rolling speed or on the linear speed of rotation of the rolls and determined from Table. 7.2. (m / s 2130 p. 60).

Similarly, using formula (7.1), we calculate the friction coefficient for each rolling pass, enter all the necessary data and calculation results in Table 7.1

Table 7.1

No. of rolling pass

8. Calculation of rolling force

Determination of the contact area of ​​the metal with the roll.

The contact area of ​​the rolled metal with the roll i-th caliber is determined by the formula:

where and are the width and height of the strip at the exit to the caliber;

and - width and height of the strip at the exit from the caliber;

The coefficient of influence of the shape of the caliber, determined by tab. 8.1. (m / s 2130 p. 60). - the radius of the roll along the bottom of the caliber.

The radius of the roll along the bottom of the caliber is determined by the formula:

where is the diameter of the roll barrel; and - height and inter-roll clearance of the caliber. Let's calculate the first pass:

All values ​​are calculated in the same way and entered in the table. 8.1.

Determination of the stress state coefficient of the deformation zone.

The stress state coefficient of the deformation zone during strip rolling for each rolling pass is determined by the formula:

where is a coefficient that takes into account the effect on the stress state of the width of the deformation zone;

Coefficient taking into account the influence of the focus height;

Coefficient taking into account the effect of rolling in the pass.

The coefficient is determined by the following relationship

The coefficient is determined by the dependence

where - caliber shape factor for non-shaped calibers (square, rhombus, oval, circle, hexagon, etc.);

Gauge shape factor for shaped gauges.

Let's calculate the first pass:

Determination of resistance to plastic deformation.

The plastic deformation resistance of the rolled metal for each rolling pass is determined in the following sequence.

Determine the degree of deformation

Then we determine the strain rate

where is the rolling speed in mm/s, we take from the table. 5.1.

define by the formula:

Let's calculate the first pass:

All values ​​are entered in the table. 8.1.

Determination of average pressure and rolling force.

The average rolling pressure for each rolling pass is:

Rolling force for each pass

Let's calculate the first pass:

All values ​​and are entered in table 8.1

Table 8.1. Calibration table

Rolling pass number	metal temperature,	Friction coefficient, f	contact area,	Stress factor states,

Continued Table 8.1.

Rolling pass number	Plastic deformation resistance	Average rolling pressure,	Rolling force, P, kN	rolling moment	Power pro- rollers N, kW

9. Raseven torque and rolling power

The moment of rolling is determined by the formula:

Similarly, we determine the moment of inertia for each rolling pass, we enter all the results of the calculation in the table.

Determination of rolling power

The rolling power is determined by the formula:

Calculation example for the first rolling pass:

Similarly, we determine the power for each pass, we enter all the results of the calculation in table 8.1.

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Article Index
Rolled steel production: classification of rolling machines, technological processes of rolling
Pipe mills and special purpose mills
Classification of rolling mills according to the number and arrangement of rolls
Blooms and slabs production
The main features of the technological process of rolling on blooming
Production of blanks on billet mills
Long products production
Calibration of rolls for rolling square profiles
Calibration of rolls for rolling of round profiles
Peculiarities of roll calibration for angle steel rolling
Production of rolled products at medium section mills
Production, rails, beams, channels
Raw material for rolling rails, beams and channels
Arrangement and location of equipment for rail and beam mills
Technological process of rail rolling
Rail quality control
Rolling of I-beams
Characteristics of the equipment and its location on the universal beam mill
Wire rod production
Continuous wire mill 250 MMK
Machine for continuous casting and rolling of steel rod
Strip and tape production
Rolling of hot-rolled strips and sheets
Raw material and its heating
plate rolling process technology
Production of two-layer sheets
Cold rolling of sheets
Production of special types of rolled products
Production of periodic profiles
Finned tube production
All Pages

Calibration of rolls for rolling of round profiles

GOST 2590-71 provides for the production of round steel with a diameter of 5 to 250 mm.

The rolling of this profile, depending on the steel grade and dimensions, is carried out in different ways (Fig. 2.7 ).

Figure 2.7. WaysI -X round steel rolling:

I - oval, rhombus or hexagon;II . IV. V- smooth barrel or boxcaliber;III - decagonal or box calibers; VI- square or hexagonal gauges; VP - circle, etc.; VIII- lancet caliber, smooth barrel or box caliber; IX, X- oval, etc.

Ways 1 And 2 differ in options for obtaining a pre-finishing square (the square is precisely fixed diagonally and it is possible to adjust the height). Method 2 is universal, as it allows obtaining a number of adjacent sizes of round steel (Fig. 2). Method 3 is that the prefinishing oval can be replaced with a decagon. This method is used for rolling large circles. Method 4 is similar to method 2 and differs from it only in the shape of the rib gauge. The absence of sidewalls in this caliber contributes to better descaling. Because this way allows wide adjustment of the dimensions of the strip coming out of the rib gauge, it is also called universal gauge. Methods 5 and 6 differ from the rest in higher hoods and greater stability of the ovals in the wiring. However, such calibers require precise adjustment of the mill, since with a small excess of metal, they overflow and form burrs. Methods 7-10 are based on the use of an oval-circle sizing system

A comparison of possible methods for producing round steel shows that methods 1-3 make it possible in most cases to roll the entire range of round steel. Rolling of quality steel should be carried out according to methods 7-10. Method 9, as it were, is intermediate between the oval-circle and oval-oval systems, it is most convenient in terms of regulating and adjusting the camp, as well as preventing sunsets.

In all considered methods of rolling round steel, the shape of the finishing and pre-finishing passes remains almost unchanged, which contributes to the establishment of general patterns of metal behavior in these passes for all cases of rolling.

Drawing2.8 Example of sizing round steel according to method 2

The construction of a finishing gauge for round steel is carried out as follows.

Determine the estimated diameter of the caliber (for a hot profile when rolling to minus) dG = (1,011-1,015)dX is the tolerance part +0.01 dX where 0.01 dX- increase in diameter for the above reasons: dX = (d 1 + d 2 )/2 – diameter of a round profile in a cold state. Then

dG = (1,011-1,015) (d 1 + d 2 )/2

Where d 1 And d 2 – maximum and minimum allowable diameter values.

Pre-finishing gauges for a circle are designed taking into account the accuracy required for the finished profile. The more the shape of the oval approaches the shape of a circle, the more accurately the finished round profile is obtained. Theoretically, the most suitable profile shape to obtain the correct circle is an ellipse. However, such a profile is rather difficult to hold at the entrance to the finishing round gauge, so it is used relatively rarely.

The flat ovals hold the wires well and, in addition, provide large swages. With small reductions of the oval, the possibility of size fluctuations in a round gauge is very small. However, the opposite phenomenon is true only for the case when a large oval and a large hood are used.

For round profiles of medium and large sizes, the ovals, outlined by one radius, turn out to be too elongated along the major axis and, as a result, do not provide a reliable grip of the strip by the rolls. The use of sharp ovals, in addition to not providing an accurate circle, adversely affects the stability of the round gauge, especially in the output stand of the mill. The need for frequent replacement of rolls sharply reduces the productivity of the mill, and the rapid development of calibers leads to the appearance of second grades, and sometimes marriage.

The study of the causes and mechanism of the development of calibers showed that the sharp edges of the oval, which cool faster than the rest of the strip, have a significant resistance to deformation. These edges, entering the caliber of the finishing stand rolls, act on the bottom of the caliber as an abrasive. Rigid edges at the tops of the oval form hollows at the bottom of the gauge, which lead to the formation of protrusions on the strip along its entire length. Therefore, for round profiles with a diameter of 50-80 mm and more, a more accurate profile execution is achieved by using two or three radius ovals. They have approximately the same thickness as an oval outlined by one radius, but due to the use of additional small radii of curvature, the width of the oval decreases.

Such ovals are flat enough to hold them in wires and provide a secure grip, and a more rounded contour of the oval, approaching the shape of an ellipse in its shape, creates favorable conditions for uniform deformation in width. .bands in round gauge.

The assortment of round and square profiles is very wide due to the wide variety of its use. Products with a square section (made of steel) are rolled with a side of a square from 6 to 200 mm or more, of a round section - from 5 to 300 mm in diameter. Dimensions (diameters) from 5 to 9 mm correspond to rolling wire, on wire mills (rolled wire); the interval of their sizes through 0.5 mm. Product sizes from 8 to 380 mm are rolled on small section mills with an interval of 1 and 2 mm; from 38 to 100 mm - on medium section mills with an interval of 2-5 mm and from 80 to 200 mm - on large section mills with an interval of 5 mm. Larger sizes of products are rolled on a rail and beam mill.

The most convenient for rolling a round profile are oval gauges (Further "caliber" - "K.";), alternating with square ones according to the system square-oval-square (Fig. 3.11, a) or by system square - rhombus - square (Fig. 3.11, b); in both cases square gauges in rolls are located on the edge. Such a distribution and alternation of k. contributes to a better compression and study of all layers of metal.

When rolling products with a circular cross section with a diameter of 5 to 20 mm, the K system, alternating, square - oval (Fig. 3.11, a). Rolled round with a diameter of more than 20 mm is carried out in calibers, alternating according to the system square-rhombus (Fig. 3.11, b). In both systems, the last three K. are common:

• prefinishing square;
• prefinishing oval;
• clean circle.

Since rolling is carried out in a hot state, to obtain products of the required diameter (which is measured cold) the dimensions of the finishing gauge should be corrected for shrinkage.

Due to the large cooling effect of the rolls in the vertical direction, the temperature shrinkage of the vertical diameter is less than that of the horizontal one. Correction of the dimensions of the finishing K. is provided if the vertical diameter of the caliber is taken d in \u003d 1.01 d x, and the horizontal d g \u003d 1.02 d x.

The gap between the rolls, depending on the diameter of the roller, is taken in the range from 1 to 5 mm; the radius of rounding of the corners of the rolls near the gap r is 0.1d x (Fig. 3.11, e).

Rolling of products of square section is carried out in calibers, alternating system rhombus-square (Fig. 3.11, c). This system is often used for rolling square profiles larger than 12 mm. Calibration begins with the determination of the dimensions of the finishing K., taking into account the unequal temperature shrinkage in the vertical and horizontal directions. To do this, the angle at the top of the finishing gauge is taken equal to 90 ° 30 "or 181/360 rad (Fig. 3.11, e).

Then the vertical diagonal of the finishing K. d in \u003d 1.41 C mountains, and the horizontal d g \u003d 1.42 C mountains, where C mountains is the side of the square in the heated state, equal to 1.013 C n. The profile that came out of such a K., when solidified, will have an exact square shape. The corners of a fine square K. are not rounded. The gap between the rolls is assumed to be from 1.5 to 3.0 mm.

The essence of the invention: the finishing gauge is symmetrical with respect to the horizontal plane of the parting, and each part of the gauge is formed by three arcs of a circle of the same radius, while the central arc is limited by an angle of 26 - 32 °, and the centers of the side arcs are shifted beyond the axis of symmetry of the streams by 0.007 - 0.08 of the radius arcs. 1 ill.

The invention relates to the processing of metals by pressure and is intended for use primarily in ferrous metallurgy, as well as in mechanical engineering. The aim of the invention is to simplify the setting of the caliber and increase the yield. The drawing schematically shows a finishing gauge for rolling round steel. The proposed finishing gauge for rolling round steel contains two streams 1 and 2, symmetrical about the horizontal axis X and vertical axis Y. Each of these streams has three sections 3,4 and 5, formed by arcs AB, BC, CD, A "B" , B"C" and C"D" of the same radius R. The central arcs BC and B"C" are limited by an angle of 26-32 o and are outlined by a radius R from the point of intersection of the X and Y axes of the caliber. Lateral arcs AB, A"B" and CD, C"D" are also outlined with a radius R, but from centers shifted beyond the vertical axis of symmetry Y of the caliber in the direction opposite to these arcs. The arcs AB and CD are outlined from the centers O 2 and O 1, and the arcs A "B" and C "D from the centers O 3 and O 4. The displacement of the centers behind the vertical axis of symmetry Y is equal to half the tolerance field for the finished profile. The gauge is equipped releases (built with a "collapse") 6. They are built according to well-known methods, drawing from points A, D and A "D", tangent to the arcs A 1 AB, CDD 1 and A 1 A "B", C "D" D 1. The upper and lower strands are installed with a gap 7 of size S. During the operation of the rolling mill, before rolling in a new finishing pass, the gap S is set such that the height of the pass corresponds to the minimum allowable value of the size of the circle diameter. After that, rolling is carried out. as the caliber grooves wear out, it is adjusted. In this case, the criterion is the "ovality" of the profile. Rolling is carried out in the caliber until it wears out in width, corresponding to the maximum allowable size of the diameter of the circle along the width of the caliber (X axis). After that, they proceed to rolling in a new caliber. as a result of increased wear of the strands in sections 4 and 5, the limiting value of the diameter of the finished profile in the corresponding sections is obtained almost simultaneously with the corresponding dimensions along the X axis. arcs 1 beyond the limits specified in the claims, the positive effect of its use is reduced, this can be seen from the table, which presents the results of rolling a circle of 1600 mm. As the experimental rolling data showed, as a result of using the proposed finishing pass for rolling round steel, metal removal from the finishing pass increased by 38%; the yield of second grades decreased by 60%. The claimed finish pass for rolling round steel is of undoubted interest to National economy, as it will reduce metal consumption: significantly increase labor productivity by at least 12% by reducing the time for transshipment.

Claim

FINISHING GAUGE FOR ROLLING ROUND STEEL, formed by two streams symmetrical with respect to the horizontal plane of the parting, limited by arcs of circles, characterized in that, in order to simplify the setting of the caliber and increase the yield of good, each of the streams is formed by three arcs of the same radius, while the centers of the side arcs are displaced for the vertical axis of symmetry of the streams by 0.007 0.08 of this radius, and the central arc is limited by an angle of 26 32 o .

DRAWINGS

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