Make a metal cone. How to make a development - a pattern for a cone or truncated cone of given dimensions

Instead of the word “pattern,” “reamer” is sometimes used, but this term is ambiguous: for example, a reamer is a tool for increasing the diameter of a hole, and in electronic technology there is the concept of a reamer. Therefore, although I am obliged to use the words “cone development” so that search engines can find this article using them, I will use the word “pattern”.

Creating a pattern for a cone is a simple matter. Let's consider two cases: for full cone and for truncated. On the picture (click to enlarge) Sketches of such cones and their patterns are shown. (I should immediately note that we will only talk about straight cones with a round base. We will consider cones with an oval base and inclined cones in the following articles).

1. Full cone

Designations:

Pattern parameters are calculated using the formulas:
;
;
Where .

2. Truncated cone

Designations:

Formulas for calculating pattern parameters:
;
;
;
Where .
Note that these formulas are also suitable for a full cone if we substitute .

Sometimes when constructing a cone, the value of the angle at its vertex (or at the imaginary vertex, if the cone is truncated) is fundamental. The simplest example is when you need one cone to fit tightly into another. Let's denote this angle with a letter (see picture).
In this case, we can use it instead of one of three input values: , or . Why "together O", not "together e"? Because to construct a cone, three parameters are enough, and the value of the fourth is calculated through the values of the other three. Why exactly three, and not two or four, is a question beyond the scope of this article. A mysterious voice tells me that this is somehow connected with the three-dimensionality of the “cone” object. (Compare with the two initial parameters of the two-dimensional “circle segment” object, from which we calculated all its other parameters in the article.)

Below are the formulas by which the fourth parameter of the cone is determined when three are given.

4. Pattern construction methods

Calculate the values on a calculator and construct a pattern on paper (or directly on metal) using a compass, ruler and protractor.
Enter formulas and source data into spreadsheet(for example, Microsoft Excel). Use the obtained result to construct a pattern using graphic editor(for example CorelDRAW).
use my program, which will draw on the screen and print a pattern for a cone with the given parameters. This pattern can be saved as a vector file and imported into CorelDRAW.

5. Not parallel bases

As for truncated cones, the Cones program currently creates patterns for cones that have only parallel bases.
For those who are looking for a way to create a truncated cone pattern with no parallel bases, here is a link provided by one of the site visitors:
A truncated cone with non-parallel bases.

Sometimes a task arises - to make a protective umbrella for an exhaust or chimney, an exhaust deflector for ventilation, etc. But before you start manufacturing, you need to make a pattern (or development) for the material. There are all sorts of programs on the Internet for calculating such sweeps. However, the problem is so easy to solve that you can calculate it faster using a calculator (on a computer) than searching, downloading and dealing with these programs.

Let's start with simple option- scan simple cone. The easiest way to explain the principle of pattern calculation is with an example.

Let's say we need to make a cone with a diameter of D cm and a height of H centimeters. It is absolutely clear that the blank will be a circle with a cut out segment. Two parameters are known - diameter and height. Using the Pythagorean theorem, we calculate the diameter of the workpiece circle (do not confuse it with the radius ready cone). Half the diameter (radius) and height form right triangle. That's why:

So now we know the radius of the workpiece and can cut a circle.

Let's calculate the angle of the sector that needs to be cut from the circle. We reason in the following way: The diameter of the workpiece is 2R, which means the circumference is equal to Pi * 2 * R - i.e. 6.28*R. Let's denote it L. The circle is complete, i.e. 360 degrees. And the circumference of the finished cone is equal to Pi*D. Let's denote it Lm. It is, naturally, less than the circumference of the workpiece. We need to cut a segment with an arc length equal to the difference of these lengths. Let's apply the ratio rule. If 360 degrees gives us full circle workpiece, then the desired angle should give the circumference of the finished cone.

From the ratio formula we obtain the size of the angle X. And the cut sector is found by subtracting 360 - X.

From a round blank with radius R, you need to cut a sector with an angle (360-X). Don't forget to leave a small strip of material for overlap (if the cone attachment will overlap). After connecting the sides of the cut sector, we obtain a cone of a given size.

For example: We need a cone for an exhaust pipe hood with a height (H) of 100 mm and a diameter (D) of 250 mm. Using the Pythagorean formula, we obtain the radius of the workpiece - 160 mm. And the circumference of the workpiece is correspondingly 160 x 6.28 = 1005 mm. At the same time, the circumference of the cone we need is 250 x 3.14 = 785 mm.

Then we find that the angle ratio will be: 785 / 1005 x 360 = 281 degrees. Accordingly, you need to cut out a sector of 360 – 281 = 79 degrees.

Calculation of the pattern blank for a truncated cone.

Such a part is sometimes needed in the manufacture of adapters from one diameter to another or for Volpert-Grigorovich or Khanzhenkov deflectors. They are used to improve draft in a chimney or ventilation pipe.

The task is a little complicated by the fact that we do not know the height of the entire cone, but only its truncated part. In general, there are three initial numbers: the height of the truncated cone H, the diameter of the lower hole (base) D, and the diameter of the upper hole Dm (at the cross section of the full cone). But we will resort to the same simple mathematical constructions based on the Pythagorean theorem and similarity.

In fact, it is obvious that the value (D-Dm)/2 (half the difference in diameters) will relate to the height of the truncated cone H in the same way as the radius of the base to the height of the entire cone, as if it were not truncated. We find the total height (P) from this ratio.

(D – Dm)/ 2H = D/2P

Hence P = D x H / (D-Dm).

Now knowing the total height of the cone, we can reduce the solution to the previous problem. Calculate the development of the workpiece as if for a full cone, and then “subtract” from it the development of its upper, unnecessary part. And we can directly calculate the radii of the workpiece.

We obtain by the Pythagorean theorem larger radius blanks - Rz. This Square root from the sum of the squares of the heights P and D/2.

The smaller radius Rm is the square root of the sum of the squares (P-H) and Dm/2.

The circumference of our workpiece is 2 x Pi x Rz, or 6.28 x Rz. And the circumference of the base of the cone is Pi x D, or 3.14 x D. The ratio of their lengths will give the ratio of the angles of the sectors, if we assume that full angle in the workpiece – 360 degrees.

Those. X / 360 = 3.14 x D / 6.28 x Rz

Hence X = 180 x D / Rz (This is the angle that must be left to get the circumference of the base). And you need to cut accordingly 360 - X.

For example: We need to make a truncated cone with a height of 250 mm, a base diameter of 300 mm, and a top hole diameter of 200 mm.

Find the height of the full cone P: 300 x 250 / (300 – 200) = 600 mm

Using the Pythagorean point, we find the outer radius of the workpiece Rz: Square root of (300/2)^2 + 6002 = 618.5 mm

Using the same theorem, we find the smaller radius Rm: Square root of (600 – 250)^2 + (200/2)^2 = 364 mm.

We determine the sector angle of our workpiece: 180 x 300 / 618.5 = 87.3 degrees.

On the material we draw an arc with a radius of 618.5 mm, then from the same center - an arc with a radius of 364 mm. The angle of the arc can have approximately 90-100 degrees of opening. We draw radii with an opening angle of 87.3 degrees. Our preparation is ready. Don't forget to allow an allowance for joining the edges if they are overlapped.

A typical technological cycle for manufacturing shells from sheet metal includes the following steps:

1) Incoming control, editing, cleaning the sheet.
2) Marking and cutting workpieces.
3) Processing of edges for welds.
4) Assembly of blanks.
5) Welding of sheet blanks.
6) Rolling (stamping) of shells.
7) Welding longitudinal seams.
8) Calibration.
9) Control.

Punching thick-walled sheets

The following animation shows the rolling process. By doing this with the entire supplier, you save both time and transportation costs. The machine is particularly precise and is mainly used for punching thick-walled cones. The machine is installed once and is therefore particularly suitable for small and medium-sized series with a constant radius. These materials can also be bent into cylinders or cones in one of our production facilities. For example, thin and thick walled tapers, concentric and eccentric tapers, gearboxes from square to round shape, column plates and arc segments.

If necessary, additional operations are also performed:

1) Beading of shells (Fig. 3). Internal ridges are used for installing supports, partitions, and gratings. External ridges - to give rigidity to the shell.
2) Beading the ends inward (for installation of bottoms and cooling jackets) or outward for mounting slip-on flanges (Fig. 4); flanging holes in the shells (Fig. 5).
3) Grinding with abrasive wheels or belts (Fig. 6).

For example, we cut sheet metal dampers from brushed metal plate with the weld edges applied directly. After bending, the longitudinal and circular seams are glued and welded. Welding is carried out in accordance with quality standards. Non-destructive testing of the material is carried out upon request.

Rolling and stamping of sheet metal in ferrous and non-ferrous alloys Production of housings, housing parts and cylinders Also for special forms, Concentric and eccentric cones, gearboxes, column linings and arc segments. Volumes: from 1 to 150 mm thick up to a maximum width of 500 mm. . Cones are transition elements or transition bodies between two tubular hollow bodies. They have the shape of a truncated cone, and the diameters of the two ends are different sizes. Thus, cones serve, for example, to connect two pipes with different radii.

The waviness of sheet blanks can cause a loss of stability of the machine shell, so the blanks must be straightened before rolling.

In the absence of the necessary equipment in small-scale or single-piece production, it is necessary to reject the unsuitable sheet at the stage of incoming inspection.

Also in industry, cones and transition parts no longer need to be thought through. The material, size and shape to be used in the manufacture of cones and transition elements always depend on their subsequent use. Preparing the cones can be done in a variety of ways. One possibility is to pump the material to achieve the desired shape. Another possibility is to produce edges with continuous curves to ensure appropriate degree rounding. Subsequently, the end edges of the cones are joined together by welding or stitching.

Sheet straightening is carried out on multi-roll machines (Fig. 7). The pitch between the rollers and the number of rollers are determined depending on the thickness of the sheet (Table 1).

Sheet blanks are cleaned using several methods:

3) Cleaning with metal rotating brushes.
4) Thermal cleaning is carried out by gas-flame heating with a burner mounted on roller supports. When heated to 150 degrees, scale is separated and rust is peeled off, which is then cleaned off with metal brushes.
5) Chemical degreasing by hand rubbing or spraying with a solvent, or in baths. After chemical degreasing, rinsing with water and drying should be carried out.

We have already released the following cones for our clients

Transition elements can also be manufactured in a square design. We are also active in the production of wear parts. For example, we produce cones and funnel-shaped transition elements for cement factories, gas stations or gravel work.

One type of cones and transition elements are funnels, which serve to fill vessels with narrow openings. In this case, liquids such as water or even fine-grained materials such as sand, gravel or granules are placed at the wide mouth of the funnel and then flow into the vessel through a thinner outlet. We can also produce funnel wear plates.

Marking of blanks on a sheet is done with chalk or a scriber using a universal measuring tool. When cutting on CNC portal gas cutting machines, markings are not required.
Workpieces are cut using guillotine shears with inclined/straight knives, disk shears or thermal methods (oxygen, arc, plasma or laser cutting). The first method is the most productive, but there are limitations on the possible thickness of the sheet.
The edges of workpieces for welding are processed on edge planers, edge milling machines, thermal cutting or manual methods in single production (grinders, files, pneumatic hammers). The shape of the edges depends on the requirements of regulatory documentation for the manufacture of vessels and apparatus and can be of several types (Fig. 9).
Rolling (bending) of sheets is carried out on two-roll machines (for thicknesses no more than 5 mm) and three-roll rolls. By moving the upper roll on three-roll symmetrical machines, the bending radius (shell diameter) is adjusted. The sheet is rolled several times (Fig. 10). After this, the ends of the shell are bent.

We produce cones and transition pieces in a limitless variety of shapes: from round to rectangular, oval, concentric, eccentric, symmetrical or asymmetrical - if necessary, also with side and neck or folded several parts. Our many years of know-how, innovative strength and solution-oriented thinking are key factors in this field, who are specialists in the field of cones and transition elements. We provide you with accurate solutions!

Cones are used, among other things, and are often shaped like a truncated cone, with the diameters of the two ends being different sizes. Cones are often also called cones, funnels, connecting cones, reducers or reducers. In their shape they are always concentric or eccentric and rounded at both ends. In the case of a transition element, special shape cones, ends may differ. The transition piece is therefore ideally suited as a connecting element between, for example, two tubes or hollow bodies with different radii.

From a flat sheet to a round shell:

Rollers with an asymmetrical arrangement of rolls (Fig. 11) produce almost complete bending of the shell.
The most modern are four-roll machines (Fig. 12), which perform rolling and hemming of edges in one cycle.
The bending radius of the shells is checked using templates. Possible defects in rolling of cylindrical shells are shown in Fig. 14.

Cones and transition elements in every strength and material quality

In addition to the cones and transitional parts, we also produce sinks and accessories of any kind. Components that cannot be transported in one piece due to their size, we produce, as far as technically possible, in a number of segments that can be assembled on site to obtain the finished product.

High precision and reliability in forming technology - just in time

In production we pay great attention outstanding quality and precision. There are many reasons why you might want to make a metal foil cone. Metal cones serve to block chimneys, up to certain types fire on outdoors and during barbecues, and sometimes for decorative purposes. Folding sheet metal is easier than you might expect, so don't be intimidated by the process. Enter it completely, but with caution, of course.

Also ways to get the desired shape there are different ones.

Bending of conical shells is done in several ways:

1) By installing at an angle the middle roll for symmetrical three-roll machines and the side roll for asymmetrical three-roll and four-roll rollers (Fig. 15).
2) Flexible midline sequentially in different areas (Fig. 16) on rollers. First, the edges are hemmed, then the middle of the workpiece is bent in each section with reinstallations. This method leads to increased wear and tear on the equipment.
3) Bending of shells on rollers with replaceable conical rolls. This method is justified in serial and mass production.
4) Rollerless method for sheets up to 20 mm thick. In Fig. 17 shows the folding method. The edges 3 and 4 of the workpiece are fixed in supports 2 and 5, brought together, and the supports are simultaneously rotated in different directions. Next, the edges of the conical shell are joined using tacks and removed from the machine.
5) The most productive method is to manufacture conical shells in dies (Fig. 18).
Before welding parts of the shells, they are pre-fixed to prevent deformation of the elements and ensure welding gaps. Aligning the edges is usually done with clamps and assembly rings for thin sheets (Fig. 19). Two clamps are installed on one shell at the ends.

The cylindricity of the shells is ensured by special devices with jacks that push the part apart. When assembling dimensional parts, tie strips and wedge connections are used (Fig. 20).

Manufacturing of a working cone to order

The pencil will draw a circle, and the small indentation that the compass left where it was supported should be marked. 2 Cut the circle using special metal foil scissors. Wear gloves so that the edges of the metal are very sharp. 3 Cut the circle in half. Using the support point of your compass as a guide and to end point, cut a straight line there starting from both ends. You will now have a circle of metal foil with a slit that starts at one side and goes all the way to the center. 4 Overlap one side of the cut over the other. Starting at the gap, press the sheet pieces one on top of the other. At the same time, you will see that the circle begins to shrink and form a cone. Stop when necessary, depending on how deep you want it. 5 Tape on each side of the overlay. This will prevent the metal from moving and get rid of rough edges. Your metal blade taper is now complete. Wear gloves whenever you handle a metal blade to avoid cutting your hands. Metal blade Scissors for metal blade Compass with pencil Duct tape Gloves. The establishment of certain uniform rules finds its rationale in the need to guarantee, in relation to all professions subject to certification, the objectives required by certificates of professionalism.

Video of bending a cone shell

When assembling the shells, roller stands (Fig. 22) and tilters are used. Welding of circumferential and longitudinal seams of shells is carried out manually, mechanized or using welding robots.
To eliminate residual stresses in the welds, the shells are subjected to heat treatment in shaft furnaces.
After welding, the shell is calibrated on rollers - rolling it in several passes.
During the final inspection of manufactured shells, their geometric dimensions, absence of deformations and surface defects of the part are checked.

A certificate of professionalism has been established corresponding to the occupation of industrial boiler, professional family of heavy industry and metal structures, which will have an official character and validity throughout the country.

Certificate of Professionalism. Accreditation of the training contract. Only transitional position. Adaptation to the national curriculum and professional plan implementation. The Minister of Labor and Social Affairs is hereby authorized to make such regulations as may be necessary for the implementation of this Royal Decree.

More details about production individual species shells, read in the sections “Ventilation”, “Drainage” and “For metal bending”.

Rolling of shells is the most important technological process, without which it is impossible to even imagine the production of cylindrical parts. Let's take a closer look at its features, technology and the tool used.

This Royal Decree comes into force the day after its publication in the Official Gazette. In Madrid on January 24. Minister of Labor and Social Affairs. Professional profile professions. For construction various elements uses cutting and forming machines, as well as electric welding equipment, and also organizes working equipment to obtain products in conditions of safety and the required quality characteristics. Build metal structures.

Construct sets of cylindrical channels. Competency 1: assembly of metal structures. Competency 2: Construction of cylindrical pipeline sets. Competency 3: Constructing cones and bunkers. Observation of hot forming does not exceed the limit temperature molecular structure material.

1 Terminology and essence of rolling

First of all, you need to understand a little basic concepts. Rolling is the processing of a metal workpiece by pressure, as a result of which its shape uniformly changes along its entire length. This is an integral stage in the production of many parts. Such an operation is carried out special tool– rolling. After such processing, finished parts or blanks are obtained, which are sent for stamping.

Not parallel bases

Unit of competency 4: creating deposits. Practical content: 690 hours. Theoretical composition: 220 hours. Cutting metals with arc plasma and manual oxygen fuel. Welding of sheets and profiles with coated electrodes. Semi-automatic welding for boiling.

Interpretation of plans for metal structures. Construction of metal structure elements. Boiler tracking and development. Construction of cylindrical pipes from sheet metal. Construction of cones and bunkers. Cutting metals with plasma arc and manual oxygen fuel.

The shell is a conical or cylindrical structural element. It can be made in the form of a rim, a ring, a short pipe or a drum. These elements are used in the manufacture of boilers, various reservoirs, tanks, as well as in other metal structures. For the manufacture of shells, non-ferrous, ferrous metals and their alloys are used.

Overall objective of the module: To apply methods and manual skills to perform cutting operations on carbon steel plates, profiles and pipes with oxygen-containing processes and ferrous and non-ferrous materials with a plasma arc under conditions of quality and safety.

Methods for producing conical surfaces on a lathe

Safety and hygiene: Oxidation, protection and risks. Safety and hygiene: arc plasma, protection and risks. Characteristics of the equipment and auxiliary elements that make up the installation of manual oxygen cutting and manual arc plasma cutting.

2 Technology and characteristics of defects

Depending on the geometric dimensions of the part and the strength characteristics of the metal, rolling is carried out with or without bending the sheet. These parameters are also taken into account when choosing equipment. Shells are manufactured in the following sizes: thickness ranges from 3 to 100 mm, element length is 30–3100 mm, and their outer diameter ranges from 20 to 280 cm. During such deformation, the stresses in the metal reach their maximum values.

Defects in the processing of conical surfaces and measures to prevent them

Oxygen defects: causes and corrections. Torch flame temperature. Gases used in oxygen fuel, characteristics. Gas pressure and flow. Heating and cutting pumps. Straight, circular, chamfer and hole drilling methods. Plasma state of gases: ionization.

From a flat sheet to a round shell

Plasma gases: argon, hydrogen, nitrogen, air. Electrodes and electrode holders for plasma arc: diameters, lengths, types. Plasma arc: transmitted and not transmitted. The main variables of the plasma cutting process are: Energy used: High frequency. Gases used: gas dissociation. Flow and pressure of gases. Defectology of plasma cutting.

This operation consists of two stages - bending and direct rolling.. The difference between the latter is the movement of bending along the entire perimeter of the workpiece. In this case, the metal is first subjected to elastic and then plastic deformation. As the bending radius decreases, the forces will increase, and all due to an increase in the layer of metal taking part in drawing.

Install manual oxygen equipment: acetylene and oxygen bottles. Hoses and safety valves. Oxygen and acetylene monoorifiers. Install a manual arc plasma cutter. Electric rectifier. Hoses and pressure gauges-flow meter. Torch and nozzles, electrode, bush and horse. Compressed air compressor with constant pressure.

Operating hand-held oxygen equipment, turning it on and off. Direct flame in carbon steel plates with carriage and pulse. Oxidation from sheet to chip and manually. Circular fumigation and drilling in sheet metal with carriage and pulse.

After rolling the shells in the metal, there may be internal stresses, which exist in three types. Zones appear between individual section zones and parts of the part. They are the most dangerous because they contribute to the occurrence various defects such as warping and cracking. They depend on the temperature gradient that occurs between in different parts parts during temperature exposure.

Stresses of the second kind, or, as they are also called, structural, can be observed among grains and within them. Arises similar phenomenon due to unequal linear expansion coefficients. In addition, it contributes to the appearance of stresses of the second kind and the formation of new phases various volumes. Stresses of the third kind arise within the volume of several cells crystal lattice.

All these stresses have a different nature of formation, with the same consequences - distortion of the crystal lattice and the occurrence of elastic deformations.

Problems can be eliminated using heat treatment, since heating and cooling changes the nature of these phenomena. For example, when the temperature rises, the surface layers expand, but the unheated core prevents this from happening. As a result, compressive stresses arise. During cooling, all processes occur in reverse order. The surface layers have a lower temperature, in contrast to the deeper ones, and are subject to tensile stresses. After final cooling, the temperature is equalized throughout the entire volume of the metal, but this does not mean at all that these phenomena will be eliminated. Some stresses may still remain in the part; they are called residual.

How else is heat treatment, such as tempering, useful? Those who are characterized by a structurally stressed state are especially in need of it. As the temperature increases, the material becomes more plastic. As the temperature increases, the operation itself must also take longer. This relieves stress to a greater extent.

3 What will cope with the rolling of shells?

Rolling of cylindrical elements is only possible using machines. Manual bending of shells is unacceptable. Also, in order to obtain a high-quality part, it is necessary to strictly adhere to the shell rolling technology.

For the production of these structural elements in production, three-roll rollers are very popular. They can be either manual or have a mechanical or electric drive. The most common arrangement of rolls is in the form of a triangle: one at the top and two at the bottom. Depending on the required parameters of the finished shell, the diameters of the rolls vary. They also differ in the rolling length; it can be either 340 or 2000 mm.

Naturally, it is much easier to work with electrical equipment, but its cost is also an order of magnitude higher, so if your plans do not include the constant production of shells, then there is no point in purchasing such expensive machines. There are also devices with one floating roller. In this case, the rolling will be relative to this element, which serves as a mandrel to obtain shells of a given diameter. Main disadvantage such machines - the need to constantly reconfigure and change the working tool if you need to get a part of a different size.

A typical technological cycle for manufacturing shells from sheet metal includes the following steps:

1) Incoming control, editing, sheet cleaning.
2) Marking and cutting workpieces.
3) Processing of edges for welds.
4) Assembly of blanks.
5) Welding of sheet blanks.
6) Rolling (stamping) of shells.
7) Welding longitudinal seams.
8) Calibration.
9) Control.

If necessary, additional operations are also performed:

The waviness of sheet blanks can cause a loss of stability of the machine shell, so the blanks must be straightened before rolling.

With absence necessary equipment in conditions of small-scale or single production, it is necessary to reject unsuitable sheets at the stage of incoming inspection.

Sheet straightening is carried out on multi-roll machines (Fig. 7). The pitch between the rollers and the number of rollers are determined depending on the thickness of the sheet (Table 1).

Sheet blanks are cleaned using several methods:

1) Sandblasting with a jet of compressed air containing particles of abrasive sand. After dry sandblasting, it is necessary to remove dust from the surface. Instead of sand, it is possible to use fine steel or cast iron shots (shot blasting).
2) Shot blasting in continuous shot blasting machines. This method is very productive and effective, however, it is not applicable for thin-sheet workpieces, since they warp during processing (the sheet thickness must be at least 5 mm). Shot blasting allows you to remove both heavy contaminants (scale) and traces of grease and oils.

3) Cleaning with metal rotating brushes.
4) Thermal cleaning is carried out by gas-flame heating with a burner mounted on roller supports. When heated to 150 degrees, scale is separated and rust is peeled off, which is then cleaned off with metal brushes.
5) Chemical degreasing by hand rubbing or spraying with a solvent, or in baths. After chemical degreasing, rinsing with water and drying should be carried out.

Based on the actual dimensions of the sheet, the nature of its edge (edged or unedged), the width of the rollers, allowances for edge processing and welding gaps, cutting is carried out - a graphical representation of the most rational (low-waste) option for cutting the sheet (Fig. 8). In this case, an individual cutting option for one or several parts of the same type is possible; mixed - taking into account other parts necessary for the manufacture of a specific unit or product; group - for a batch of products, in this case large parts are cut out first, then smaller ones. The cutting coefficient is defined as the ratio of the net weight of the part to the consumption rate for the part, taking into account cutting. The higher this coefficient, the more economical the cutting.

The blanks are marked on the sheet with chalk or a scriber using a universal measuring tool. When cutting on CNC portal gas cutting machines, markings are not required.
Workpieces are cut using guillotine shears with inclined/straight knives, disk shears or thermal methods (oxygen, arc, plasma or laser cutting). The first method is the most productive, but there are limitations on the possible thickness of the sheet.
The edges of workpieces for welding are processed on edge planers, edge milling machines, thermal cutting or manual methods in single production (grinders, files, pneumatic hammers). The shape of the edges depends on the requirements of regulatory documentation for the manufacture of vessels and apparatus and can be of several types (Fig. 9).
Rolling (bending) of sheets is carried out on two-roll machines (for thicknesses no more than 5 mm) and three-roll rolls. By moving the upper roll on three-roll symmetrical machines, the bending radius (shell diameter) is adjusted. The sheet is rolled several times (Fig. 10). After this, the ends of the shell are bent.

From a flat sheet to a round shell:

Also, the methods for obtaining the desired shape are different.

Bending of conical shells is done in several ways:

1) By installing at an angle the middle roll for symmetrical three-roll machines and the side roll for asymmetrical three-roll and four-roll rollers (Fig. 15).
2) Flexible along the center line sequentially in different areas (Fig. 16) on rollers. First, the edges are hemmed, then the middle of the workpiece is bent in each section with reinstallations. This method leads to increased wear and tear on the equipment.
3) Bending of shells on rollers with replaceable conical rolls. This method is justified in serial and mass production.
4) Rollerless method for sheets up to 20 mm thick. In Fig. 17 shows the folding method. The edges 3 and 4 of the workpiece are fixed in supports 2 and 5, brought together, and the supports are simultaneously rotated in different directions. Next, the edges of the conical shell are joined using tacks and removed from the machine.
5) The most productive method is to manufacture conical shells in dies (Fig. 18).
Before welding parts of the shells, they are pre-fixed to prevent deformation of the elements and ensure welding gaps. Aligning the edges is usually done with clamps and assembly rings for thin sheets (Fig. 19). Two clamps are installed on one shell at the ends.
The cylindricity of the shells is ensured by special devices with jacks that push the part apart. When assembling dimensional parts, tie strips and wedge connections are used (Fig. 20).

Video of bending a cone shell

After assembly, the welding gap is checked and tack welding is performed (Fig. 21). The parameters of the tacks are given in Table 2. Lead-in and lead-out strips are used to ensure a high-quality weld at the ends of the shell.

When assembling the shells, roller stands (Fig. 22) and tilters are used. Welding of circumferential and longitudinal seams of shells is carried out manually, mechanized or using welding robots.
To eliminate residual stresses in the welds, the shells are subjected to heat treatment in shaft furnaces.
After welding, the shell is calibrated on rollers - rolling it in several passes.
During the final inspection of manufactured shells, their geometric dimensions, absence of deformations and surface defects of the part are checked.

For more information about the manufacture of individual types of shells, read the sections “Ventilation”, “Drainage” and “For metal bending”.