WO2013020241A1

WO2013020241A1 - Production of tubes by continuous casting

Info

Publication number: WO2013020241A1
Application number: PCT/CL2012/000013
Authority: WO
Inventors: Arturo GAMBOA BRISSOS
Original assignee: Madeco S.A.
Priority date: 2011-08-10
Filing date: 2012-03-13
Publication date: 2013-02-14
Also published as: CL2011001935A1

Abstract

To date, in the copper-tube-manufacturing industry, three technologies have been successfully demonstrated in connection with the forming of a pre-tube that constitutes the base of the copper tube. One technology involves an extrusion of a solid component, known in casting jargon as a "billet", by means of a hydraulic oil press and using heat for this purpose, and after formation of the first press-extruded pre-tube the latter is processed using a Pilger, or pilgrim-step, cold-rolling mill, resulting in formation of the pre-tube. The second technology involves hot-deformation of a solid copper billet in a "piercing" rotary rolling mill and using heat for this purpose, resulting in the pre-tube. Lastly, there is a technology called "cast & rolls" technology, wherein a cast tube is obtained (the liquid copper contained in a furnace is solidified by means of a continuous, horizontal cooling system), which is continuously deformed in a planetary rolling mill (downstream of the casting system), from which emerges a dynamically recrystallized pre-tube. There are other methods for manufacturing pre-tubes, such as where the pre-tube is obtained directly from pressing without a rolling process, but such methods are of less significance. In this case, "former pre-tube" is the term given to the product obtained by means of the second technology described above, which pre-tube customarily has a diameter of around 60 mm and undergoes various processes in order for it to be given the ultimately required thickness and diameter. The invention set forth in the present description considers using an ascending vertical, continuous casting smelting and solidification technology, with a matrix, a positioning ring and a cooling device, which are specially calculated and designed to form pre-tubes continuously from a smelting furnace. The invention likewise considers that the graphite-designed matrix makes it possible to manufacture tubes with smaller diameters, using solidification of the material to produce tubes of different nominal diameter, which allows a substantial saving in the subsequent process for achieving the required diameters, permitting optimization of energy, of process steps, of material and of quality far above that which is currently known.

Description

TUBE PRODUCTION THROUGH CONTINUOUS COLADA

There are currently various manufacturing techniques in the pipe and pipe manufacturing industry. In the case of pipes, it usually exists by bending sheet metal and subsequent seam welding. This technique is usually used for pipes of larger diameters.

The second current way of making tubes is by means of a solid metal cylinder, usually called a banknote or billet (this technical term will be used in everything that remains of memory) to which a high temperature is applied and then exempted in a high press pressure or pierce and lengthen it by mechanical systems under two techniques known as "piercing" or "pilgrimage". These two current manufacturing techniques result in what is known in the industry as "pre tube" or for us pre old tube. This pre tube has a predetermined length for the size and weight of the billet. Currently in the industry the weight of the billet ranges from 75 to 400 kg which restricts the size of the pre tube. As indicated in the document "Mechanical Technology: Metrology and metal shaping processes without chip removal.", "Materials" Collection of the UJI, n ° 233.de Carlos Vila Pastor, Fernando Romero Subirón, Gracia M. Bruscas Bellido and Julio Serrano Mira.

Once the old pre-tube is formed, it goes through a series of drawing processes that basically consist in lengthening this tube and determining the thickness of its walls by passing through a metal die with a pepe inside it until the desired result is achieved as It is described later in Figure 5.

This means that the system consists of a dice that is a plate that has a hole in its center. The pipe is threaded through this hole, but a pipe is placed inside the pipe on the upper side of the plate. The pepa is a metal cylinder with a diameter slightly greater than the hole in the plate that, when pushed by the pipe, locks and allows the thickness of the wall to be reduced while passing through the die. This process is necessary exclusively because the initial tube (pre-old tube) leaves the process with a diameter greater than 60 mm which forces it to be reduced until reaching the desired commercial measures. It is important to note that each reduction cannot exceed 30% of the original dimension so it is necessary to pass the tube repeatedly through this process.

The material losses due to this process are of the order of 25-35% depending on the size of the tube, the greater the initial length of the old pre-tube, the smaller the losses, since these are mainly from three sources, the first source of loss Material is stippling. In order to reduce the size of the tube, the machine requires deforming the first 30 or 40 cm of tube in each pass to be able to pull it, which is then lost. The second source of loss is the ruptures of material, as the diameter of the tube decreases the tractions become more intense since the material accumulates them in each pass, if there is any imperfection in the tube this is cut and a loss occurs of material. Finally, the third source of loss is the final sizing of the product that will depend directly on the length of the old pre-tube or weight of the billet, the greater the weight, the less loss. This entire process is energy and material intensive, which results in excessive costs and significant losses that must be reprocessed. In addition to the above, the failures are dangerous for the exposed personnel since, being stressed, they can be projected out of the machinery, causing accidents of various considerations. Today the state of the art in the industry is the handling of billet or cylinders of the order of 400 kg. With three to four passes through wire drawing. If you want to reach smaller diameters for refrigeration, it is necessary, in addition to the above, to add passes through special equipment, more sensitive and usually through a more exhaustive quality control. The process of the present invention consists in completely changing the way in which the seamless tubes were manufactured to date. The process presented consists of melting in a smelting furnace in a temperature range between 80 ° C to 5000 ° C, specifically in the range between 500 ° C and 2000 ° C, specifically 1 160 ° C (similar to those provided for the manufacture of cables and solid bars of copper), a metallic and / or non-metallic material, more specifically a metal, a metal alloy, a composite metal, a metallo-ceramic alloy, ceramic or a polymer, preferably copper. Once the molten material is present, the molten material is passed through metastatic pressure through a system comprising a matrix placed by a ring of Pre-removed positioning, subsequently cooled by a cooler and the pre-tube removed with a continuous extractor. These elements are specially designed for the manufacture of tubes by means of a process called vertical continuous casting casting, in which the material is raised to form the almost finished tube (pre-tube). In this matrix there are perforations in its lower base and external surface that allow the laundry material to enter a continuous laminar flow, cooled by a perimeter mantle through a closed circuit with demineralized water, at a pressure in a range of between 2 to 10 Bar, specifically 4 to 6 Bar (cooler). The casting speed is based on a flow, specifically with a Reynolds of 1 (laminar flow) that allows to form concentric and continuous rings of solidified casting forming a tube at the exit of the system, with a speed of between 20 to 0.1 mt. minute, more specifically 1 mt the minute of tube produced, with a diameter and a thickness in the ranges of 1 to 50 cm and 1, 2 to 3.5 mm respectively, more specifically 3.8 cm and 2.5 mm. The material discharged continuously is rolled, the weights of the rolls (pre-tube) located in the range of 75 to 2000 kg. After obtaining this almost finished tube (pre-tube), it is cut in the cutter in the length that it is needed and is wound on reels between 60 to 100 inches, more specifically 213.36 cm (84 inches) in diameter. After this, the process continues with the roll going to the oven for initial crystallization, once the tube is softened or crystallized it is ready to go to the router or Skinner (this technical term will be used in everything that remains of memory) to reduce up to the requested diameter. Once this is done, the roll is cut back into the cutters and passed to a finishing oven if required, to finally be packed and sent to the cellars.

A second aspect that makes up the following invention is the system comprising an oven, the die, the positioning ring, the cooler and the extractor. The oven used is preferably one of continuous casting, more specifically of vertical continuous casting. This oven works by magnetic induction type omega channel, with a broad content capacity although more specifically 12 tons. Through static meta pressure, molten material is passed through the die. Outside the area of the molten material and centering the matrix is the positioning ring, which is removed to begin the process. In addition to the three previously mentioned parts, there is the cooler, which by recirculation of demineralized water cools the outlet of the pre tubes. Thirdly, another aspect comprising the present invention is a matrix and a positioning ring both of a temperature resistant material, which withstand hot deformation and high thermal conductivity, specifically constituted of graphite but not excluding other materials such as Composite materials, industrial diamond, ceramics, composite ceramics, alloys specially calculated and designed for this purpose.

This matrix comprises two parts, a cylinder-shaped body recessed in its external body and a conical body recessed in its interior with a cylindrical base with a wide range of dimensions, more specifically with a dimension between 42 mm to 60 mm for the first body in its external part and in its internal part of 38 to 40 mm. In the second part, for the conical internal body, the dimensions in its external part are between 30 to 33 mm.

Specifically, the matrix has a hollowed conical internal body, emptied along both parallel faces with a wide penetration depth for the upper plane, specifically between the range of 50 to 95 mm, while emptying along the axis in The lower flat face is in the range of 10 to 35 mm.

The matrix in its hollowed out external body and along its entire axis retains a relationship between the perforation of the upper plane of the hollowed conical internal body part and the hollowed out external body of between 5 to 50 mm. The matrix in its hollowed-out cylinder-shaped body in its external part and in the cross-section to the axis of symmetry has between 3 to 4 perforations with diameters between 2 to 5 mm, while for the hollowed conical internal body the same is repeated number of perforations, specifically 3 to 4 with diameters of 2 to 5 mm.

The matrix in its conical internal body hollowed in its cross section to the axis of symmetry in its upper parallel plane has in its central part a perforation of between 20 to 28 mm, specifically 25 mm, while for its lower plane transverse to the axis of symmetry It has a central perforation between 12 and 21 mm. The matrix in its cross section, between bodies in the form of an external recessed cylinder and a recessed conical body, has a ratio of angles between its perforations between 0 to 60 °.

The invention contemplates as one of its main characteristics the entrance of the material to the matrix, placing an entrance in the external part of the mantle and another in the internal part of the mantle. The balance of the material flow is directly related to the entry section of these through perforations specifically offset by 60 °.

The following table describes the superficial relationships that this design contemplates.

Matrix Design Table

positioning Figure 2 (3)

Equal to internal diameter Figure

Internal diameter 2 (1) outer mantle surface part of smaller diameter.

The matrix preparation process is achieved by machining pieces of graphite in a cylindrical shape while retaining the larger diameter of the base and performing internal perforations. The internal termination is done with mirror polishing (for which the internal dimensions must be finished).

After forming the cylinders described in Figure 2 in numbers 1 and 2, the external dimensions are terminated, leaving them with fine polishing.

The assembly of parts numbers 1 and 2 is produced by pressure at the base of both.

On the other hand, the positioning ring has a thickness range of between 3 to 20 mm, specifically 7 mm, retaining an internal diameter equal to that of the hollowed cylinder-shaped body and a variable external diameter.

The positioning ring is used independently of the matrix, it is located just at the moment of laying of the matrix within the cooling system. Once this process is finished, part number 3 of figure 2 is broken by lever. To specify this process, just before placing the matrix, the positioning ring is introduced through the parallel external plane, while the matrix and rings are positioned in the cooling system. The die is introduced into the cooling system to the limit defined by the positioning ring. Once the matrix is in its correct position, the positioning ring is split and removed from the place to free the matrix as indicated in Figure 7.

The development of this matrix and positioning ring solves, among other problems, all those related to vertical, transverse, branched cracks, reduction of inclusions in the external and internal surfaces and the trephilability of the tube in steps following. This being the first viable process of manufacturing pipes at an industrial level in the world.

For the resolution of the problems described above, CFD numerical solution techniques, experimental solidification techniques, design and real solidification tests and solidification metallurgical engineering were used.

Finally, the system also comprises a cooler and a continuous extractor, the first one has the purpose of rapidly cooling the generated pre-tube and the extractor has to remove that newly formed pre-tube from the solidification site of the pre-tube.

The advantages of this process are among others:

1. It does not limit the size of the lot to the size of the billet since it is of continuous casting which minimizes the use of energy, losses of material and maintains the quality.

2. It does not require a previous smelter for the manufacture of the cylinders since it has a smaller and proper smelter, this reduces energy consumption, significantly improves the emissions of a smelting process and increases safety by having fewer stages of heating the cylinder .

3. It improves the quality of the initial tube (pre tube), being a laundry and not a pressure process the tube has a lower residual tension which allows its structure to be better formed and with less deformation. In addition, unlike the experiences known so far in continuous manufacturing, it gives the tube a stability that allows all its processability.

4. It allows tubes of various sizes and in particular those of smaller diameter which implies a smaller termination process, this is extremely important for energy consumption and material losses, since less processing steps are required to reach the final product.

5. The power to start from smaller pre-tubes allows to reach smaller tube diameters with better safety and quality because the laundry has been exposed to less stress. 6. It allows to develop new forms and applications of tubes, being a liquid laundry allows to form practically any form of tube for the development of new applications hitherto unknown or possible.

7. Productivity, being a continuous system allows productivity several times better than currently known by the industry. This is mainly because the new matrix allows a workable quality and stability of the product that did not previously exist.

Brief description of figures. Description of figure 1

LONGITUDINAL AND HORIZONTAL CUTS OF THE MATRIX

(1) EXTERNAL DROPPED CYLINDER

(2) CONNECTED CONICAL BODY

(3) UPPER FLAT DROPPED CYLINDER

(4) BOTTOM PLANE UNDERWATER CYLINDER

(5) SUPERIOR FLAT CONICAL BODY

(6) BOTTOM FLAT CONCRETE BOWED

(7) POLISHED MIRROR

(8) CROSS CUTTING CROSS CUTTING

(9) CROSS CUTTING CROSS CUTTING

(10) CROSS CUTTING OF THE ASSEMBLY Description of Figure 2

LONGITUDINAL AND OPERATIONAL COURT OF THE MATRIX

(1) MATRIX HAND, EXTERNAL CONE (cylindrical unit with flat base)

(2) MANDRILE OF THE MATRIX, INTERNAL CONE (conical unit with flat base)

(3) POSITIONING RING (ring-shaped unit) (4) INTERNAL DRILLING

(5) EXTERNAL HAND METAL INCOME

(6) INTERNAL DRILLING

(7) INTERNAL HAND METAL INCOME In Figure 2 the matrix developed for this system is composed of graphite and consists of two pieces, one inside and one outside that uniform the output flow through a series of channels that are forming solidification rings of the pre tube at an approximate speed of 1 mt / min, which when cooled form the pre tube that comes out from the other end of these nozzles.

Description of figure 3

TUBE MANUFACTURING SCHEME IN THE STATE OF ART (1) PRESS PIPE EXTRUSION

(2) EXTRUSION OF PIPE BY PEREGRINE PASS

(3) PUNTEADORA

(4) DECAPAR

(5) BANK MAYOR 120

(6) MANCHES MINOR 100

(7) SAW CUT

(8) BANK MINOR 50

(9) ENDOREZADORA

(10) BULL BLOCK (ROLLER TREFILADOR)

(1 1) CUTTER

(14) OVEN

(15) PACKING

(16) WINERY In Figure 3 a flowchart of the old process known in the state of the art is described starting at point (1) or (2) according to whether the tube is extruded in the press or in a pilgrim's passage. This process generates what is called an old pre tube), basically it is a hollow cylindrical shape obtained from a metal filled cylinder. Once the Pre-tube the tip must be made in the process (3), so that then, with the following machinery, take and stretch the pre-tube to form a proper tube through the drawing process.

Once this is done, in step (4) proceed to behead. This process is an acid bath to the tube so that all the oxide inherent in the extrusion or piercing process can be removed. Finally, the tube passes to the bank, which is part of the drawing process, taking the tip to pass a bowl through a die, "lengthening" and reducing the diameter of the tube. (Figure 5) Depending on the diameter and length of the tube, it is directed to other smaller banks indicated in numbers (6) or (8). If the tube is too long for the bench, it must be cut by means of a saw indicated in point (7) and then straightened in the straightener (9) to draw again. Once the defined wall diameter and thickness is reached, it goes to the bull block indicated in point (10). These machines allow drawing in rolls so as to have a longer length. It must pass through a bank since the latter must reduce the diameters so that the bull block can operate. At the end of the passes through the bull block the tube passes to cutters (1 1) to cut the roll into tubes of the required length, then if it is necessary to soften the tube for certain applications it passes to the finishing oven (14) and then be packed in the packing area (15) and exit to the warehouses (16). Description of figure 4

TUBE MANUFACTURING SCHEME IN THE INVENTION

(1 1) CUTTER

(12) VERTICAL CONTINUOUS COLADA FOUNDING OVEN

(13) SPI NER

(14) OVEN

(15) PACKING (16) WINERY

Figure 4 describes the heart of the process of the technology protected here (12) in which an almost finished tube (pre-tube) of a measure close to that finally required is taken out. This pre tube is ready to go through a cutter (1 1) that this time reduces the diameter and cuts into lengths appropriate for the rest of the process. Once this is done, the roll goes to the oven for initial crystallization (14), once the tube is softened or crystallized, it is ready to go to the Skinner (13) to reduce to the requested diameter. Once this is done, the roll is cut in the cutters (1 1) and passed to a finishing oven if required (14) to finally be packed (15) and sent to the cellars (16).

Description of figure 5

TRADITIONAL TREATMENT SCHEME OF THE OLD PRE TUBE

(1) MATERIAL OR TUBE

(2) PEPA OR BULLET

(3) TREFILATION DATE This figure 5 describes the traditional treatment that receives an old pre-tube, it goes through a series of drawing processes that basically consist of lengthening this tube and determining the thickness of its walls by passing through a die metallic with a pepe inside to achieve the desired result as described in the figure. Description of figure 6

LONGITUDINAL AND HORIZONTAL CUTTING OF THE POSITIONING RING (1) TOP RING FLAT

(2) CROSS CUTTING OF THE RING Figure 6 presents 2 cuts of the positioning ring, this ring exerts its function extemporaneously, this means that once the matrix is to be introduced, the guide ring is used, then it breaks and the process begins.

Description of figure 7

INTEGRATED SYSTEM

(1) COOLING SYSTEM

(2) POSITIONING RING

(3) MATRIX

Figure 7 shows three integrated system parts, in dark black the positioning ring is seen which has been removed for the operation of the system.

Application examples

Comparative processes Normal process:

1.- As an example of the normal process known by the state of the art, we can take the manufacture of a standard pipe of nominal diameter ¾ for the construction industry. The flowchart of this process can be seen in Figure 3. In a normal manufacturing process the tube is initially extruded or obtained by some mechanical process as already mentioned above. Since the tube was heated and deformed, it is necessary, for handling, to clean it from any impurity or trace of rust. For this, a process called "pickling" is carried out, which consists of a chemical bath to remove these impurities. After cleaning the tube, the tip is manufactured so that it can be reduced, once this is done, it goes to the drawing banks, these are banks of approximately 30 to 40 meters in length where the tube is lengthened. If necessary, longer tubes should be cut in some intermediate reduction, as shown in the flowchart of the previously described figure. Once the initial reduction in the banks has been carried out and a standardized roll or of a diameter close to the desired one is produced, it goes on to a roll drawing process in machines called bull block or Skinner, these perform the same function as the banks but accept smaller diameters and Tubes longer than banks are not able to process. Once the desired diameter and thickness is reached, it is passed through an oven and then cut into the commercial lengths that are required as seen in the process of Figure 3. All these rolls do not weigh more than 300 kilos in the best of the industry .

Process of the invention: 1.- In the case of the continuous casting process, the tube is produced in a diameter close to the one finally desired, after producing about 12 tons of liquid copper in the continuous casting, by static meta pressure, It passes the material through the matrix, previously positioned with the positioning ring (it is eliminated when the process begins), with a laminar flow of a Reinols of 1. This hot pre-tube is cooled through distilled water in recirculation to a pressure of 4 to 6 bar, to finally deliver a copper tube at a speed of 1 meter per minute, with 3.8 cm in diameter and 2.5 mm thick in rolls of diameter of 84 inches (213.36 cm) that are cut at the desired weight (approximately 800 kg per roll) and passed through the oven for handling. Once this event has occurred, it is only necessary to go through the final reducing equipment and then cut the final product. Pickling, banks or more cuts than those of the work lot are not required, thus achieving, in a fraction of the time, the final product.

Claims

1. Process for the production of metallic and non-metallic tubes CHARACTERIZED because it comprises the following stages:

a) Blend in a continuous casting furnace a metal, a metal alloy, a composite metal, a metal-ceramic alloy, ceramic or a polymer.

b) use of a temperature-resistant matrix and positioning ring.

c) pass a metal or a metal alloy, a composite metal, a metal-ceramic alloy, ceramic or a liquid polymer through a matrix previously positioned with a positioning ring from the continuous casting and then cool the pre tube with the cooler.

d) cut the pre-tube according to the length that is required.

e) reduce the thickness of the pre-tube until it reaches the required diameter of the final dimensioned tube.

2. A process for the production of metallic and non-metallic tubes according to claim 1 CHARACTERIZED in that the continuous casting furnace operates at temperatures between 80 to 5000 ° C to melt metals, metal alloys, composite metals, metallo-ceramic alloys , ceramics or polymers.

3. A process for the production of metallic and non-metallic tubes according to claim 2 CHARACTERIZED in that the continuous casting furnace operates at temperatures between 500 and 2000 ° C, more specifically 1 160 ° C to melt copper.

4. A process for the production of metallic and non-metallic tubes according to claim 1 CHARACTERIZED in that the metastatic pressure of the metal alloy, composite metal, metallo-ceramic alloy, ceramic or polymer is carried out with an inlet laminar flow in the system with a Reinols equal to 1 and an output flow of the system comprising the pre-tube flow of 1 mt / min.

5. A process for the production of metallic and non-metallic tubes according to claim 1 CHARACTERIZED because at the exit of the pre-tube, it is cooled through the chiller by demineralized water in recirculation at a pressure of between 2 and 10 Bar.

6. A process for the production of metallic and non-metallic tubes according to claim 1 CHARACTERIZED in that it comprises the passage of the metal alloy, composite metal, metal-ceramic alloy, ceramic or polymer through a matrix previously positioned with a positioning ring .

7. A process for the production of metallic and non-metallic tubes according to claim 1 CHARACTERIZED because the manufactured pipes can be made of metal, a metal alloy, a composite metal, a metallo-ceramic alloy, ceramic or a polymer.

8. A process for the production of metallic and non-metallic pipes according to claim 7 CHARACTERIZED because the pipes manufactured are made of copper.

9. A system for the production of metallic and non-metallic tubes CHARACTERIZED because it comprises a continuous casting furnace, a die, a positioning ring and a cooler.

10. A system for the production of tubes according to claim 9 CHARACTERIZED in that the casting furnace, the die, the positioning ring and the cooler are made of thermo-resistant materials, such as graphite, composite materials, industrial diamond, ceramics, composite ceramics, alloys.

1 1. A CHARACTERIZED matrix because it comprises two parts, a recessed outer cylinder and a recessed conical body that fit together.

12. A die according to clause 1 1 CHARACTERIZED because the external recessed cylinder and the recessed conical body have perforations and an angle between them from 0 to 60 °.

13 A matrix according to clause 12 CHARACTERIZED because these perforations are between 3 and 4.

14. A matrix according to clause 1 1 CHARACTERIZED because it is wrapped by the cooler.

15. A CHARACTERIZED positioning ring because it positions the matrix and is then removed.

16. A positioning ring according to claim 15 CHARACTERIZED in that it comprises an internal diameter equal to that of the external body of the die.

17. A CHARACTERIZED cooler because it wraps the matrix and solidifies the pre tubes.

18. A cooler according to claim 17 CHARACTERIZED in that the pre-tubes are cooled by recirculation with demineralized water.