DE3034792A1 - Continuous seamless tube mfr. - in single prodn. line having melting, casting, machining, drawing and shearing stations - Google Patents

Abstract

In a seamless tube mfg. process, the operations of metal melting, holding, continuous tube casting, tube transport, internal and external machining of the tube surface, multi-stage drawing, straightening and cutting into tube lengths are carried out in sequence in a single prodn. line. The initial tube dia. and wall thickness are pref. chosen so that no intermediate heating stage is required. There is no interruption in the prodn. flow and no intermediate transport of the product is required. Heating is only required for the initial melting stage and no scrap ends are produced.

Description

Process for continuous

Manufacture of seamless tubes Process for continuous Production of seamless pipes The production of seamless pipes is compared to Pro-Ç The operation of welded pipe is much more complex and therefore more expensive.

However, since it is more economical to manufacture along the spira seam welded Pipe cannot be produced for all purposes (e.g. with thick walls and small outside diameters or in general with difficult or non-weldable ones Materials) also retains the seamless pipe for a wide range of applications Meaning.

The invention therefore has the task of finding ways and means with the help of which the production of seamless tubes can be made more economical can be.

The traditional way of making seamless tubes is relative worldwide similar.

A cast or forged one is used as the starting point for production short rulldling is used, from which a very thick-walled sleeve is created. This sleeve is then extruded, again Rolling or pushing in processed into a relatively short pre-blank. This Vorluppe runs through then preferably a hot stretch reducing mill or a cold pilger plant or a pipe drawing bench, where it is given its desired shape according to the final dimension.

Most of the above operations must be carried out at hot rolling temperature take place, with repeated heating due to the large number of individual stations of the rolling stock is unavoidable.

All of this is very energy and costly, especially since protruding (1 not all - but only the main production stations - have been listed.

It is known to be the starting point for pipe production in the vertical Production of continuous casting process as a thick-walled hollow profile. But also arise here still very thick-walled pre-bulbs, all of the downstream systems mentioned as individual pieces have to go through.

It is also known - especially with non-ferrous metals - and is preferred here in copper pipe production - to try the turn of horizontal continuous casting, but here, too, only individual tube blanks are manufactured.

These pipe blanks can also only be very short, since they are shed when they are poured on the inner and outer skin of the hollow fine shrinkage cracks, the inside and must be removed mechanically on the outside.

he machining on the inner surface of the pipes is by mechanical means Conditions are limited and this results in the brevity of the required preliminary groups.

The invention has therefore set itself the task of a method to develop, with the help of which the production of seamless tubes, fully continuously - from melting down the starting material to cutting the pipe to commercial length - takes place in only one heat and in only one production line.

To solve this problem, a method is proposed such as is essentially characterized by the claims.

Then the production flow is planned in such a way that the base material, from which Jas pipe is made - for example copper - at the beginning of the line is melted down. After reaching the casting temperature, the melting furnace is tilted and part of the liquid metal enters the holding furnace at its outlet one according to the intended pipe diameter and the associated wall thickness matching ring mold is attached, from the cross section of which the desired hollow profile emerges continuously after intensive cooling. The solidified hollow body is detected by a transport device and conveyed on in a horizontal position. To compensate for the different casting movements, the strand has a loop curve the opportunity to commute before being hit by one of the double-working The drawing trolley of a technically known straight-line drawing machine is detected - and transported onwards will. In the drawing ring holder area of the 1st drawing system, according to the invention, there is an outer and an inner metal cutting ring and 2 pull rings are arranged.

According to the invention, after the pipe string has been precisely rounded in the 1st drawing ring the even peeling of the outer skin of the pipe by one of the hard metal cutting rings. With this ring, at least 0.3 mm of the initial wall thickness will be mechanically clean so that with certainty the fine Ilaar cracks that occurred during casting no longer exist. In the area of the 2nd drawing ring is located inside the pipe string the 2nd cutting ring, according to the invention, the fine hairline cracks on the circumference of the inside of the pipe mechanically clean cg peeled.

According to the invention, this hard metal cutting ring is on the inlet piece a pipe mandrel attached, which extends over the pipe wall on the conical part of the 2. Drawing ring is supported. The peeled chips build up against the direction of production seen in the pipe string.

The length of the pipe string between the pouring mold and the inner one Cutting ring must therefore be so long according to the invention that in this gap there is enough space inside the pipe to last for at least 12 hours to be able to pick up all metal chips. (For a pipe with an inner diameter of 60 mm this distance is approx. 9 m).

Since the casting mold is usually changed every 10 hours, there is with this downtime the possibility of completely removing the chips from the corresponding Suck off pipe piece and thus free space again for the next mold trip to accomplish. The pipe string now free of all oxides and cracks on the outside and inside now runs through the drawing ring according to the invention of at least one further straight-line drawing machine and receives its final dimensions in the process.

A technically known straightening system aligns the strand in accordance with the sale just. A likewise technically known rotating pipe cutting device subdivided the current strand in commercial lengths.

This method according to the invention brings the number of those sought Benefits to their full extent.

From melting down the material to ejecting the finished end product there is no interruption of the production flow and thus no hissing transport of the products.

The entire process takes place in just one heat, namely in the, which was necessary to melt the material.

By choosing the casting mold with dimensions that are relatively close to the All further operations can be carried out cold. Due to the continuous operation of the line, there are no pieces of lint the disadvantageous final wasteX The pipe precisely calibrated on the outside in the 2nd drawing ring enables the inner cutting ring, also to machine the inner diameter exactly centrically round. As a result, there is no longer any eccentricity in the finished pipe, but an absolute one uniform wall thickness. This advantage over the currently with conventional Pipes manufactured by the system result in a material saving of at least 20% in favor of the pipes now manufactured using the new process.

The arrangement and design of the Shown method according to the invention.

Ls show: FIG. 1: A schematic side view of the entire production line Figure 2: The arrangement and design of the hard metal cutting rings within the Pull ring holding area of the 1st pull-out device According to FIG. 1 the production flow begins when the pipe material is melted down in the melting furnace (1), from which the liquid material enters the holding furnace, at its exit the hollow profile device (3) in the form of a suitable, water-cooled ring mold is appropriate.

As a result of the water cooling, the melt solidifies in the pouring device (3) and leaves the same as a completely cast hollow strand (4). The strand transport system (5) transports the pipe string (4) according to the specified pouring outlet movement in the space (6), where the hollow strand (4) in the form of a Schlirige the different As a result, the casting movements oscillate at a constant speed from the two pulling carriages (7) and (8) of the 1st straight-line drawing system (9) in the direction of production is promoted forward. After passing through the drawing ring area of the 1st straight-line drawing system (9) the pipe string (43) reaches the area of the 2nd straight-line pulling system (10) and is continuously practically "hand over" by the two drawing carriages (11) and (12) Hand "pulled through the drawing ring (13) of the drawing system (10), in which it is its final Dimension received.

After passing through the straightening unit (14) it becomes continuous Multiple drawn pipe string (4) moving in the direction of production from the moving one Pipe cutting device (15) divided into commercial lengths.

lig. 2 shows the pulling ring area of the 1st (leravleausziehanalge (9). After passing through the 1st drawing ring (16), the pipe string (4) is precisely calibrated and thus guarantees that in the 1st tiartine valley Ischneidering (17) the (iusscre The pipe circumference is cleanly mechanically machined to a depth of at least 0.3 mm. Of the The 2nd drawing ring, adapted to this new pipe diameter! 18) guides the continuous Pipe string (4) very precisely and thus secures the precise cutting effect of the 2nd hard metal cutting ring (19), which inside the pipe the pipe circumference in a Cleanly mechanically machined depth of at least 0.3 mm. The cutting ring (19) is on attached to the inner mandrel (20). About the wall thickness (21) of the pipe string (4) the mandrel (20) is supported on the surface of the conical drawing area (22) of the Drawing ring (18) and thus gives the cutting ring (19) a fixed and precisely positioned Breakpoint. The chips (23) peeled off inside the pipe are stored in the hollow strand (4) collected in the area of the pipe string loop (6) and when changing the mold at the level of the pouring device (3) by means of a technically known suction device conveyed out of the pipe string (4).

All features mentioned in the preceding description and / or are shown in the drawing, provided that the known state of the art this allows, on its own or in any combination or partial combination are regarded as essential to the invention, even if they are in the claims are not included.

Claims (9)

Claims 9 method of making seamless tubes thereby characterized in that the operations metal melting (1), keeping warm (2), Ilohlprofilgießen (3), strand transport (5), mechanical processing of the outer and inner pipe surface, the multiple ~ pulling straight ahead (9), (10), straightening (14) and separating (15) the continuously running pipe string (4) one behind the other in just a single production line are arranged. 2) Method according to claim 1, characterized in that the starting diameter of the pipe string (4) and its wall thickness (21) are designed so that the further Processing to the end product can be carried out cold without intermediate heating. 3) Method according to claim 1, characterized in that between Pipe transport (5) and the drawing ring (16) such a large pipe loop in the area (6) It is established that 1. the tinterschielliche Gießaustrittsbewegungitng leveled out and 2. so much pipe can be stored that the through the peeling process in the Späc (23) inside the pipe accumulated in the pipe string for a period of 12 h can be. 4) Method according to claim 1, characterized in that the outer Peel off the pipe circumference to a depth of at least 0.3 mm using a hard metal cutting ring (17) takes place, which is arranged behind a drawing ring, with the help of which the pipe string (4) precisely rounded - and thus the prerequisite for even peeling the outer skin of the pipe string (4) is created by the cutting ring (17). 5) Method according to claim 1 and 4, characterized in that in Height of the 2nd drawing ring (18) inside the tube of the strand (4) a 2nd hard metal cutting ring is arranged, which peels off the inner surface of the pipe string (4) by at least 0.3 mm. 6) Method according to claim 1, 4 and 5, characterized in that the artmetall cutting ring (19) is attached to the inner mandrel (20) and that the cutting ring (19) on the support of the mandrel (20) by means of the wall thickness (21) on the pipe string (4) on the conical surface (22) of the Zichring (18) in one precisely and firmly positioned working position is held. 7) The method according to claim 1 characterized thereby} lnet, dc according to the Drawing part (9) at least one second drawing part (10) with corresponding drawing ring equipment is arranged in a line, with the help of which the pipe string is clean inside and out (4) Retains its final dimensions in terms of diameter and wall thickness. 8) Method according to claim 1, characterized in that instead of a hollow profile, a solid strand can also be cast, which as well as the hollow profile up to the inner peeling - all production stages up to the finished dimension runs continuously. 9) Method according to claim 1-9, characterized in that the material all pourable and drawable materials are used for the manufacture of the end product can get.