DE112008003085T5 - Method for producing seamless steel tubes with a large diameter - Google Patents

Abstract

A method for producing large diameter seamless steel tubes, comprising heating a solid cylindrical blank, applying a glass based lubricant thereon to the die and sequentially punching the blank in a die in a vertical hydraulic extruder in a cycle by means of a die Press mandrel with preliminary (pre) pressing of the blank and pressing of the tube by a direct method with discharge of the metal under the action of a press die with a press die through a die down, separating the tube obtained from the press residue and removing the tube from the die, characterized that the lubricant contains graphite in a volume ratio to the glass of (1: 4) to (1: 5), the preforming of the blank is carried out with the aid of the press mandrel and the blank punching is carried out with a tensile coefficient of at least 1.4, wherein Punching process of Rohli ng is supported on a continuous support and the ram continuously increases with increasing height of the blank ...

Description

The Invention relates to the field of metalworking by forming, in particular the technology of manufacturing seamless steel tubes.

The most efficient manufacturing process for seamless steel tubes large diameter are methods that are on the application based on the method of hot pressing (extrusion). Compared to other known methods (forging and machining, drilling and pulling) this process ensures a higher Accuracy of the dimensions and shape of the pipes, the possibility of Production of pipes of great length, of pipes made of medium and high alloy steels, of bimetallic tubes, including those with a plated inner layer Stainless steel; a higher process performance and less metal waste.

As state of the art for the present invention, a technological process for the production of steel tubes with a diameter up to 1200 mm on vertical hydraulic extruder presses with a force of 30,000 Mp and 35,000 Mp from the company "Cameron" ( Avery D. How, "Cameron vertically extrudes seamless pipe", Metal Progress 1977, Vol. 3, No. 2, pp. 52-57 ) serve. Further state of the art is the production of pipes with a diameter up to 1400 mm on a vertical extruder press with a force of 45 000 Mp according to a later project, which was developed in the period 1980-1990 in the USSR ( VS Starikov et al., "Tekhnologiya i instrument dlya proizvodstva stalnykh trub bolshogo diametra metodom pressovanija"["Method and tool for the production of large-diameter steel tubes by pressing"], Kuznetchnoshtampovotchnoe proizvodstvo, 1988, No. 10, pp. 14-17 ).

The Production of pipes by means of the known methods mentioned is characterized by a direct pressing process, in which the Pipe emerges upwards and with the help of a cutter from the press residue is separated. During the pressing process remains the while pressing at the table the press ram immobile the recording with the die moves from top to bottom towards him becomes. In contrast to the technology realized with the presses of the company "Cameron" and which provides for the use of a graphite based lubricant, can press on a press with 45 000 Mp with a highly effective lubricant On a glass basis, the higher quality the surface of the obtained pipes and an increase ensures the service life of the pressing tool. this will achieved by a newly developed construction of a pressing tool with a free (not attached to the punch) pressure washer (SU Inventor's Certificate No. 1274889, "Tool for pressing Tubes ").

Of the biggest disadvantage of the mentioned technical analogues insists on the necessity of using hollow blanks the extruder press. This disadvantage leads to the need the insertion of an additional extensive Equipment (a forging press or a punch press) for the provision of such blanks in the construction of the tube press plant. This leads to a significant increase in the cost of creation the plant and its subsequent operation.

As the closest prior art relating to the present invention, the method of producing seamless steel pipes according to RU Patent No. 2166394 to watch. The most important advantage of this method over the aforementioned analogs is that it allows the use of massive blanks. This is achieved by performing the punching of the blank directly on the extruder press, the punching operation being combined with the subsequent tube pressing operation in one working cycle of the press. Thus, a combined punching and pressing operation is performed.

The Method according to the closest prior art comprises the steps heating the blank, applying a (technological) glass lubricant on blank and tool and successively on a vertical hydraulic Extruder press performed blank punching with help a pressing needle (a mandrel) with preceding (pre) pressing the Blanks in a receptacle with the help of a punch and pressing by a direct method, with the tube passing through the die emerges down, with the help of the movable ram and a free (not attached to the latter) pressure washer, wherein recording and die are stationary, as well as separating the obtained tube from the press rest by cutting off with a at the Press specially provided device.

at the production of pipes of the normal, most widespread Assortment ensures the procedure according to the Nearest prior art, a significant reduction the investment required for the establishment of pipe production, of labor and operating costs (energy costs, tooling costs, and maintenance costs, etc.) in pipe manufacturing an increase in the proportion of products produced by hot pressing Pipes on the total volume of production of seamless steel pipes and creates favorable conditions for the construction of metallurgical mini-operations and for the organization own pipe production in the prefabrication departments of Engineering companies.

however perform some of the essential features of the procedure of the closest prior art in the case of special seamless steel tubes with large diameter (400-500 mm and larger, up to 1400 mm), u. a. in pipes with greater wall thickness (up to 100 mm), with serious disadvantages in the manufacture of such pipes with this method.

So is used for the production of pipes by the method of the closest Prior art requires an extruder press, in addition to the main drive for pressing the pipe through the working stroke the press stamp another quite powerful independent Drive for the execution of the working stroke of the Dorns when punching the starting blank has and also with an elaborate. Device for separating the pipe from Press rest is provided. All of this increases proportions and weight of the press, thus increasing their manufacturing costs. In this circumstance lies the main drawback of the closest-state procedure the technique in the case of its application for the production of large-caliber Pipes. At this point it must be noted that even a press with a force of 45 000 Mp used for the production of pipes a diameter up to 1400 mm from hollow blanks is determined according to a the above-mentioned analog method and no powerful Punching system and no separator has, yet already Dimensions of 31.1 × 14.9 × 52.7 m (length × width × height) has. The entire pressing plant reaches a weight of 20,000 tonnes. Further disadvantages of the method according to the closest State of the art with regard to the production of pipes with large diameter consist in the need of separating of the tube from the press rest directly in the press and the punching of the Blanks under supports on the press die. this leads to extending the duration of the production cycle of the Tube in the press and to an enlargement of the Amount of metal waste ("slug") received when the spike pierces the bottom of the perforated blank. It should be remembered that when making a pipe with a diameter of 1400 mm and a wall thickness of 100 mm a press with 45 000 Mp the weight of the original Hollow blanks reached 18 tons.

Regarding these disadvantages of the method to the nearest The state of the art is especially to be considered that the construction of a tube press plant for the production of hot-pressed Large diameter pipes and the operation of such Plant with particularly high financial expenditure and material expenditure connected is. Therefore, the ratios are in terms of profitability and competitiveness of a built pipe production of particular, primary importance.

The The main object of the present invention is to provide a method of making large diameter seamless steel tubes, based on the summary of the operations of punching the Blank and pressing the tube in one cycle of the extruder press, a reduction of investment in the establishment of Pressing plant and the running costs during their operation, thanks to a simplification of the construction, a reduction of the Dimensions and weight of the press, an increase the productivity of the tube pressing process and a reduction the amount of metal waste when punching and pressing. Thus, with the help of the invention, the most serious disadvantages of all known analogous methods and the closest state overcome the technology.

The said object is achieved in that the inventive Process for the production of seamless steel pipes big Diameter heating a solid cylindrical blank, the application of a (technological) lubricant based on glass on this and on the pressing tool and successively in a vertical hydraulic Extruder press performed in a work cycle punching of the blank in a receptacle with the aid of a press mandrel with preceding (pre) pressing of the blank and pressing the tube by a direct method with leakage of the metal under the action of a ram with Press disc through a die down, as well as separating the obtained Pipe from the press residue and remove the pipe from the die. there contains the (technological) lubricant graphite in one Volume ratio to glass from (1: 4) to (1: 5). The pre-pressing of the blank is done with the help of the press mandrel, and the punching of the Blank is carried out with a tensile coefficient not less than 1.4. During the punching process, the blank is supported on a continuous Pad off, and the punch moves with increase in height of the blank continuously upward. For punching and The pressing is done using a pressure washer, which is fixed to the press die is appropriate. The removal of the tube from the die takes place after transferring the die to a position for removal of the Product by relocating the tube with the press rest after above, wherein the separation of the press residue outside the Press is performed.

• • Dadurch, dass das Schmiermittel Graphit enthält, der sehr gute Antifriktionseigenschaften besitzt, wird die Bewegung des gepressten Rohrs durch die Matrize beim Entfernen und das Herausdrücken des Pressrestes aus der Aufnahme erleichtert und der Gefahr des „Festfahrens” des Pressstempels mit der an ihm befestigten Pressscheibe in der Aufnahme bei seinem Rückhub nach Herausdrücken des Rohrs vorgebeugt.
• • Das Lochen des Rohlings mit einem höheren Verformungsgrad erlaubt es, das (Vor)Pressen des Rohlings in der Aufnahme vor der Lochung nicht mit dem Pressstempel, sondern mit dem Dorn vorzunehmen, und verringert (wegen der geringeren Wanddicke des gelochten Rohlings) den Verformungsgrad, der noch beim darauffolgenden Pressen erforderlich ist, und somit auch die Nennkraft des Hauptantriebs der Presse. All dies erlaubt es, sowohl das Lochen als auch das Pressen durch diesen einen Antrieb vorzunehmen, und die Notwendigkeit eines unabhängigen leistungsstarken Antriebs für den Dorn entfällt.
• • Das Abstützen des Rohlings auf einer einstückigen Auflage (und nicht auf der einen inneren Arbeitskanal aufweisenden Matrize) während des Lochens ermöglicht eine Verringerung der Dicke des ungelocht bleibenden Bodenteils des Rohlings und somit eine Verringerung des Umfangs der Metallabfälle in Form als sogenannter „Butzen” beim anschließenden Durchstoßen des Rohlingbodens mit dem Dorn.
• • Die kontinuierliche Aufwärtsbewegung des Pressstempels mit Pressscheibe während des Lochens des Rohlings – im Gegensatz zum früheren einmaligen Anheben auf die Endgröße des Höhenzuwachses des Rohlings – ergibt bessere Bedingungen für die Zentrierung des Dorns durch die Pressscheibe während des Lochungsvorgangs.
• • Durch die Verwendung einer Pressscheibe, die fest am Pressstempel befestigt ist, entfällt die Notwendigkeit ihres Verbringens in die Aufnahme bei jedem Presszyklus und die Notwendigkeit einer zusätzlichen Vorrichtung zur Trennung der Pressscheibe vom Pressrest.
• • Das Entfernen des Rohrs aus der Matrize durch dessen Transfer nach oben ohne vorheriges Trennen des Rohrs vom Pressrest in der Presse selbst mit Hilfe einer speziellen Abtrennvorrichtung, die Teil der Presse ist, führt zu einer Vereinfachung der Konstruktion der Presse und verkürzt die Dauer des Arbeitszyklus der Rohrherstellung in dieser Presse. Die Ausführung dieses Arbeitsgangs in aus der Achse der Presse verschobener Position erleichtert die Übernahme der Rohre aus der Presse und ihr Stapeln.

The process according to the invention has the following advantages:

• The fact that the lubricant contains graphite, which has very good anti-friction properties, facilitates the movement of the pressed tube through the die during removal and squeezing of the press residue from the receptacle and the risk of "jamming" the punch with the press attached to it disc in the recording during its return stroke after pushing out of the tube is prevented.
• The punching of the blank with a higher degree of deformation makes it possible to carry out the (pre) pressing of the blank in the receptacle before punching, not with the punch, but with the punch, and reduces the degree of deformation (due to the smaller wall thickness of the perforated blank), which is still required in the subsequent pressing, and thus also the nominal force of the main drive of the press. All this makes it possible to perform both the punching and the pressing by this one drive, and eliminates the need for an independent high-performance drive for the mandrel.
• Supporting the blank on a one-piece support (and not on the inner working channel) during punching enables a reduction in the thickness of the uncontaminated bottom portion of the blank and thus a reduction in the amount of metal scrap in the form of so-called "slugs" then piercing the blank bottom with the mandrel.
• • The continuous upward movement of the die with the die during blank punching - as opposed to the former one-time lift to the final height increase amount of the blank - provides better conditions for centering the mandrel through the die during the piercing operation.
• • The use of a press washer fixedly attached to the ram eliminates the need for it to be loaded into the mold every press cycle and the need for an additional device to separate the press ram from the press ram.
• • The removal of the tube from the die by transferring it upwards without first separating the tube from the press residue in the press itself by means of a special separating device which forms part of the press, simplifies the construction of the press and shortens the duration of the working cycle pipe making in this press. The execution of this operation in shifted from the axis of the press position facilitates the acquisition of the tubes from the press and their stacking.

The mentioned advantages of the invention ensure the fulfillment their above tasks.

The present invention is described in the attached drawings 1a-c, 2a-d and 3a-c shown schematically the technical process of pipe production according to the new process in a vertical hydraulic press according to the Registration No. 2007 134334 with priority from 17.09.2007 show.

These Press possesses a movable rack with an upper and a lower crossbar and, between them, a holder for the recording with a drive and a stationary Traverse. On these are in the corners leading columns of the frame attached, above is a movable table attached, and below is arranged the main drive, which is a group of working cylinders each with arranged on the immovable Traverse housing and piston connected to the lower crosshead. The pressing tool consists of receiving, mandrel, punch and die. The mandrel is attached to the upper crosshead of the movable frame. The ram is located at one between this Traverse and the recording additional traverse attached, which is an auxiliary drive for moving the ram relative to the mandrel. The complete tool also includes a support (a pad) for punching. The press die and pad for punching are arranged at two positions on the table of the press. At the bottom Traverse of the movable frame is a stop to Ejecting the finished tube from the die, and on the immovable traverse is a vertical groove for Movement of a pipe from an axis of a press out in position designed for removal.

1 shows the technical steps of punching the blank (a - placing the blank in the receptacle, b - finishing the (pre) pressing of the blank, c - ending the punching),

2 shows the technical stages of pressing the tube (a - placing the die in the axis of the press, b - piercing the bottom of the perforated tube block, c - starting the pressing of the tube, d - finishing the pressing of the tube,

3 shows the technical stages of removal of the pipe from the die and from the press (a - removal of the press residue from the fixture, b - transfer of the die with the pipe to the position for removal of the pipe, c - removal of the pipe from the die and removing it from the press.

The Production of a pipe according to the invention Procedure is performed as follows.

In the starting position are the thorn 1 that with the upper crossbar 2 the frame of the press is connected, and the recording 3 in an upper end position, while the punch 4 that is attached to the additional crossbar 5 the press is arranged, with the pressure disk attached to it 6 is in a position in which the underside of the dummy block is located near the exit of the cavity of the receptacle. The edition 7 for punching, at the table 8th is arranged, is in a position in the axis of the press. The heated massive blank 9 with glass-graphite lubricant applied to its side face is inserted into the axis of the press in the space between the receptacle and the support ( 1a ) and arranged on the support. On the top of the blank is a portion of the same lubricant in the form of a disc 10 applied, wherein the diameter of the lubricant disc corresponds to the diameter of the mandrel. Then the recording is lowered to the support, in which case the blank is located within the recording.

Then the punching of the blank begins. First, with the help of (not shown) auxiliary drive of the press die is lowered onto the blank. Then begins with the help of (not shown) main drive of the press the working stroke of the frame with the mandrel. First, the mandrel bends the blank (presses him) until there is no gap between the side surface and the recording. During the compression process, the blank shortens. In this case, the press ram moves downward, wherein it continues to be supported on the blank with the end face of the press disk. After (pre) pressing the blank ( 1b ), the mandrel continues its downward movement, penetrates into the blank and punctures it, forming a cylindrical cavity in the blank ( 1c ). In this case, the displaced during punching metal of the blank moves in opposite directions to the movement of the mandrel upwards. At the same time, the press ram also moves upwards with the help of the auxiliary drive, thus giving room to the extending blank. After completion of the hole remains in the blank at its lower end a wall (a bottom) of small thickness.

After punching the blank, the tube is pressed. Initially, the pickup, mandrel and pressing punch move a short distance upwards. The table carries the matrix arranged in it 11 in the axis of the press, wherein on top of the die glass-graphite lubricant in the form of an apertured disc 12 is applied ( 2a ). The recording lowers on the matrix. Further, with a short stroke of the needle, the bottom of the perforated blank is pierced, with the metal scrap of the blank in the form of a grout 13 is obtained ( 2 B ). Now the upper traverse of the frame, in which the mandrel is held, and the additional traverse, in which the press ram is arranged closed. This is followed by the working stroke of pressing. Under the action of the main drive of the press, the mandrel and the press die move with the pressure washer downwards. Under the pressure of the ram, the metal of the hollow blank is shaped like a tube 14 displaced into the annulus between matrix and mandrel ( 2c ). The pressing is completed when in the female mold part of the unpressed blank with a small thickness 15 (the pressing residue) remains and there is a small distance between the crosspiece of the press ram and the top of the receptacle, which corresponds to this thickness ( 2d ).

After pressing, removal of the obtained tube from the press is performed. The mandrel moves up and out of the press rest. The receptacle with the press rest therein is raised slightly until it rests against the cross bar of the press ram. In this case, the press rest held above by the stationary press ram is pushed out of the holder ( 3a ). Thereafter, the table moves the die with the tube therein to the position for removing the tube, and the pad for punching is brought into the axis of the press. At the same time press ram and mandrel move up to the starting position, and the recording is raised over the table for the introduction of the next blank in selbige ( 3b ). Then the frame of the press begins its movement in the upper end position. During this movement acts on the (not shown) lower cross member of the frame fixed stop 16 on the lower end of the pressed tube and pushes it up through the die to a distance corresponding to the stroke of the frame. Subsequently, the tube is pressed on the rest with the help of a crane 17 finally removed from the matrix ( 3c ), which completes the manufacturing cycle of the tube in the press. The separation of the pressed residue from the pressed tube takes place outside the press with the aid of a special separating device.

Of the Use of the present invention allows for a considerable Improvement of technical and economic indicators the production of large diameter seamless steel pipes, which are needed in basic sectors of the economy, including thick-walled pipes used in many industrial objects of the new generation used in which higher pressures and temperatures be used, for example in modern nuclear and thermal power plants.

Summary

The invention relates to the field of metal working by forming, in particular the technology of producing seamless steel tubes. The method comprises heating a solid cylindrical blank, applying a glass-based lubricant thereto and onto the glass Press tool, punching the blank, pressing the tube, separating the tube obtained from the press residue and removing it from the die. The punching and the pressing are carried out in a vertical hydraulic extruder press in a working cycle of the press. The blank is carried out in the receptacle by means of the press mandrel with preceding (pre) pressing of the blank. The tube is pressed by direct process with discharge of the metal under the action of the press ram with pressure washer through the die down, the tensile coefficient is at least 1.4. The lubricant contains graphite in a volume ratio to the glass of (1: 4) to (1: 5). The invention allows to summarize the operations of blank punching and tube pressing, simplifying the construction and reducing the size and weight of the press, increasing the productivity of the tube pressing process, and reducing the amount of metal waste resulting from punching and pressing ,

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - RU 2166394 [0006]

Cited non-patent literature

• - Avery D. How, "Cameron vertically extrudes seamless pipe", Metal Progress 1977, Vol. 3, No. 2, pp. 52-57 [0003]
• - VS Starikov et al., "Tekhnologiya i instrument dlya proizvodstva stalnykh trub bolshogo diametra metodom pressovanija"["Method and tool for the production of large-diameter steel tubes by pressing"], Kuznetchnoshtampovotchnoe proizvodstvo, 1988, No. 10, pp. 14-17 [ 0003]

Claims (1)

A method for producing large diameter seamless steel tubes, comprising heating a solid cylindrical blank, applying a glass based lubricant thereon to the pressing tool, and punching the blank successively in a vertical hydraulic extruder in a working cycle in a receptacle by means of a Press mandrel with preliminary (pre) pressing of the blank and pressing of the tube by a direct process with discharge of the metal under the action of a press die with a press die through a die down, separating the tube obtained from the press residue and removing the tube from the die, characterized that the lubricant contains graphite in a volume ratio to the glass of (1: 4) to (1: 5), the preforming of the blank is carried out with the aid of the press mandrel and the blank punching is carried out with a tensile coefficient of at least 1.4, wherein Punching process of the Rohl ing is supported on a continuous support and the ram moves continuously with increase in the height of the blank upwards, for the punching and pressing a pressure washer is used, which is fixedly attached to the ram, the tube after the transfer of the female in a position to remove the product by displacing the tube with the pressing residue upwards out of the die, and separating the pressing residue from outside the press.