DE1427915B2 - ROLLING MILL FOR MANUFACTURING SEAMLESS PIPES - Google Patents

Description

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The invention is concerned with the further processing of products produced in a piercing mill Tube blanks to seamless tubes by stretching the blanks over a fixed mandrel bar without Intermediate heating. It is based on a rolling mill for the production of seamless tubes in one Heat from a piercing mill with a fixable mandrel bar for producing a tube billet a block and a downstream tube rolling mill to reduce the tube billet over a Mandrel bar consists.

In known rolling mills of this type, the plug or mandrel belonging to the piercing mill is rotatable at the end of a mandrel bar supporting it against the feed direction, onto which the Luppe is pushed.

Before the billet can be transferred to the downstream pipe rolling mill, it must be removed from the The mandrel rod previously loosened from its anchorage must be separated. To do this, as well as for any insertion A new mandrel bar running through the tube rolling mill with the hollow shell results in long relative axial movements of hollow parts and mandrel bars and correspondingly large distances between the two rolling mills required, and during the time required for the rod change, the pellet suffers heat losses, which makes the interposition of a heating furnace necessary, especially if the pipe drawn from the billet over the mandrel bar is further processed in a draw frame reducing mill shall be.

The object of the invention is to design a rolling mill of the type mentioned in such a way that it the production of seamless tubes with low wall thickness from hollow parts produced in a cross rolling mill using the heat supplied to the ingot before it is used in the piercing mill allowed.

It solves this problem in that the support rod for the mandrel of the cross rolling mill is used as a mandrel rod is designed for the tube rolling mill and for transferring the loosened from the piercing mill Mandrel bar with the hollow to the pipe rolling mill a roller table and devices for setting the rear mandrel rod end and intended for introducing the tube blank into the tube rolling mill are.

The mandrel bar thus initially serves as a support rod for the rotatable mandrel of the cross rolling mill and after the billet emerges from this rolling mill with its part introduced into the tube rolling mill as Rolling mandrel that determines the inner diameter and thus the wall thickness of the pipe. The overpass from the hollow and mandrel bar from the cross rolling mill to the tube rolling mill is a short distance away and possible in a short time, so that the heat losses can be kept as low as possible, and also the heat losses associated with the usual use of special plug or mandrel bars are avoided.

About the fixed with its rear end mandrel rod, the hollow can in one or more Steps stretched to the pipe, and the pipe pushed over the front end of the mandrel bar can if desired are fed directly to a stretch-reducing mill.

The rolling mill according to the invention also allows the tube wall thickness in a correspondingly greater The number of successive roll stands can be largely reduced by using the mandrel bar an extension protrudes through downstream scaffolding. It is recommended to use the mandrel bar to be designed so that they reach into at least one downstream frame of the pipe rolling mill Has extension with decreasing cross-section in the rolling direction. The decreasing cross-section then prevents the pipe from rolling down on the extension.

If the mandrel bar extension, with its decreasing cross-section, has a slim conical shape, then it is possible by longitudinally moving the mandrel bar that of a roll stand with the part lying in it the mandrel bar extension formed caliber to change within certain limits and thus in the same roll stand to produce pipes or pipe parts with different wall thicknesses. The longitudinally displaceable one The conical mandrel thus allows very finely graduated and therefore precise influencing in the simplest possible way the pipe wall thickness.

The extension of the mandrel bar, which has a decreasing cross-section, can be combined with a further, cylindrical Be provided extension that protrudes into at least one end stand of the pipe rolling mill. This With the cylindrical mandrel bar extension, the stand then acts as a sizing or smoothing mill.

An embodiment of the the subject

The rolling mill forming the invention is shown schematically in the drawing in three working stages.

The transverse rolling mill 1, which is used to form an ingot or billet into a tube blank, has its Discharge rollers 6 are connected to the tube rolling mill 7 via the roller table 5, 5 ′. The roller table is 5 ' can be raised and lowered to align the tube billet 2 to be fed to the tube rolling mill 7 on the roll center. The tube rolling mill consists of four stands 9, 10, 11 and 12, the caliber openings in the rolling direction to the outside diameter of the tube 2 'to be produced from the tube blank 2 (FIG. 3). from the end of the mandrel bar 3 facing the piercing mill is the rotatable mandrel through which the Tube blank 2 was rolled and pushed onto the mandrel bar 3, has already been removed. The mandrel bar 3 has at its end facing the tube rolling mill a conical extension 3 'with in the rolling direction decreasing cross-section to which a further, cylindrical extension 3 "with a dem Internal cross-section of the pipe 2 'to be produced is connected to the corresponding cross-section.

A device 8 for fixing the mandrel bar 3 is arranged in the area of the roller table 5 ', which in the drawing as the forked end of one of »5 a hydraulic cylinder extendable piston rod is indicated, which is in an annular groove 3 '"on rear end of the mandrel rod 3 can be inserted. The distance of the device 8 from the tube rolling mill? is dimensioned so that the fixed mandrel bar through the caliber opening of the first Pipe rolling mill stand 9 protrudes. The tapered mandrel bar extension 3 'then extends through the Frame 10 up to the caliber opening of the frame 11, and the cylindrical extension 3 ″ extends from the caliber opening of the frame 11 through the last frame 12.

Immediately in front of the pipe rolling mill 7 is a device 4 for insertion above the roller table 5 ' arranged the tube bobbin. It is to adapt to pipe blanks of different cross-sections adjustable in height and serves to push the tube blank 2 into the first stand 9 of the tube rolling mill 7th

As shown in FIGS. 2 and 3 can be seen, the tubular blank 2 in the framework 9 on the through its caliber opening protruding front end of the mandrel bar 3 stretched and the stretched part over this The end of the mandrel bar is pushed off and onto the conical extension 3 '. In the framework 10 is also the Outer cross-section also reduces the inner cross-section of the pipe, with both an increase how a decrease in the pipe wall thickness and a further stretching of the pipe can result. A same one The process takes place in the framework 11, from which the pipe is attached to the cylindrical mandrel rod extension 3 "is pushed on. On this extension 3" the pipe with frame 12 is rolled to size and smoothed. The F i g. 3 shows that by axially adjusting the mandrel rod 3, the cross-sections the parts of the conical extension 3 ′ lying in the frames 10 and 11 are changed and thus the wall thickness of the pipe part deformed in these scaffolding can be influenced.

1 sheet of drawings

Claims (5)

Patent claims: 1. Rolling mill for the production of seamless tubes in one heat, consisting of one Skew rolling mill with a fixable mandrel bar for producing a tube billet from a block and a downstream tube rolling mill for reducing the tube billet via a mandrel bar, thereby characterized in that for the use of one and the same mandrel bar (3) in the cross rolling mill (1) and in the tube rolling mill (7) a roller table (5, 5 ') for transferring the loosened mandrel bar (3) with the tube blank (2) to the tube rolling mill (7) and devices (4 and 8) for Fixing the rear end of the mandrel bar and for inserting the tube blank (2) into the Tube rolling mill (7) are provided. 2. mandrel bar for the rolling mill according to claim 1, characterized in that it has a Extension (3 ') extending into at least one frame of the tube rolling mill (7) with in the rolling direction having decreasing cross-section. 3. mandrel bar according to claim 2, characterized in that the extension (3 ') is conical Has shape. 4. mandrel bar according to claim 2 or 3, characterized in that its extension (3 ') with a decreasing cross-section up to at least one end stand of the tube rolling mill (7) protruding cylindrical further ones, which determine the inside diameter of the outgoing pipe Extension (3 ") follows. 5. Rolling mill according to claim 1, characterized in that the opposite of the pipe rolling mill (7) fixed mandrel bar (3) is adjustable in its axial direction.